Plate Tectonics Box

In this box are an assortment of lessons to teach students about earthquakes and plate tectonics. As students progress through the unit, evidence supporting the theory of plate tectonics accumulates. ...

In this box are an assortment of lessons to teach students about earthquakes and plate tectonics. As students progress through the unit, evidence supporting the theory of plate tectonics accumulates. They begin by researching the 10 largest earthquakes over the last 30 years. This information is plotted on a world map along with information about the location of active volcanos and mid-ocean ridges. From there, students see patterns and can determine the boundaries of the Earth's plates. To learn what lies below the Earth's surface, students take a journey from the center of the Earth to the surface, then study how convection currents in the mantle may be partially responsible for driving the movement of the plates. With the knowledge that there are tectonic plates floating on convection currents, students put it all together and build models illustrating sea floor spreading, plate motion, and the types of plate boundaries. Students incorporate the fit of the continents, coal deposits, fossils, and more into their developing model. The unit concludes with a tour of plate boundaries around the globe - India, Japan, Iceland, and California. Two field trips - to the Marin Headlands and to the Lawrence Hall of Science - are described. A project where students build earthquake-proof towers is also provided.

1. The Big One

Summary
San Francisco, 1906: Aftermath of the 7.8 magnitude earthquake that caused an estimated 3,000 deaths and $524 million in damage.San Francisco, 1906: Aftermath of the 7.8 magnitude earthquake that caused an estimated 3,000 deaths and $524 million in damage.Students use the USGS World Earthquake Archive to research the major earthquakes in recorded history. Each student is given a range of dates and assembles a table of facts on 10 earthquakes within that time frame. Students present their research and plot the locations of their earthquakes on a large world map, thereby discovering distinct earthquake zones that define the boundaries of the earth’s plates (see the Plate Patterns activity for ways to elaborate on this idea).

Objectives
Can use the USGS Earthquake Archives to research information about historically important earthquakes around the world.
Can diagram and explain what causes earthquakes in general terms.
Can understand and use basic earthquake terminology (fault, epicenter, magnitude, etc.)
Can use latitude and longitude information to plot locations on a world map.

Vocabulary
fault
earthquake
epicenter
magnitude
seismogram
latitude
longitude
tectonic plate

Attachment Size
big_quake_handout.doc 222.5 KB
big_quake_dates.doc 29 KB
1big_quake_v2.doc 58 KB

1. The Big One - Logistics

Time
5-10 min earthquake demo
35-45 min computer research
45-50 min present research, plot on large map, look for patterns

Grouping
Individual

Materials

  • 2 pieces of Plexiglas
  • scotch tape
  • Optional: Monopoly houses and game pieces
  • Computers with internet access
  • Copy of “The Big One” handout for each student
  • Copy of the “Big Quake Dates” sheet, cut into strips with one time period on each strip
  • Large world map, preferably laminated or coated so that removable sticky dots can be easily applied then removed after the activity.
  • 1 package 1/4” to 1/2” removable color dots (available in most stationary stores and drug stores for labeling maps and documents, each package usually contains 4 colors of dots: red, yellow, green and blue)

Setting
Computer lab

1. The Big One - Background

Earthquake epicenters 1963-1998: Image courtesy of NASA.Earthquake epicenters 1963-1998: Image courtesy of NASA.
Teacher Background
An earthquake is the shaking that results from stored energy in the Earth that is suddenly released. When an earthquake occurs, seismic waves travel through the earth and can be measured by a seismograph (see the background section of the Earthquake Fingerprints activity for more information).

Most earthquakes (particularly the largest ones) occur at the boundary between 2 tectonic plates. Briefly, the Earth’s crust is composed of several large plates that are in slow but constant motion across the surface of the planet (see the background section of the Plate Patterns activity for more information). The boundary between two plates is the fault. There are many types of faults that push past one another in different ways – strike-slip (where the plates slide past each other like in the demo), normal and thrust (where one plate slides up relative to the other.

I demonstrate this concept with 2 Plexiglas sheets laid side by side on the table. I tape the junction with scotch tape. The 2 pieces of Plexiglas represent 2 of Earth’s tectonic plates; the gap between them represents the fault. The scotch tape represents the friction between the plates – all the soil and rock at the junction that prevents the plates from sliding past one another freely. Then slowly I push the plates past each other in opposite directions, one pushing away from me, one pulling towards me. A bunch of energy is stored and then suddenly, the tape fails and the plates jump apart in a sudden release of energy. Put a couple of Monopoly houses on each piece of Plexiglas and the point is driven home.

The activity that follows has students conducting research on historically significant earthquakes around the world using the USGS Earthquake Archive. Each student is assigned a time frame to research and picks 10 earthquakes in that time frame to record information about. There are around 36 time frames available. The following day, they share details about one of the earthquakes they researched and plot each of the 10 earthquakes on a large world map in the classroom.

What is revealed is a very uneven distribution of earthquakes around the world. Almost all the earthquakes cluster along plate boundaries where plates are colliding (convergent boundaries) or sliding past one another (transform boundaries) although earthquakes occur at divergent boundaries as well.

An alternative way to achieve the same result is to track and plot the locations of earthquakes around the world day by day for several weeks/months until a pattern emerges. The USGS earthquake center provides a daily list of earthquake occurrences on their website with latitude, longitude, and magnitude information.

Student Prerequisites
None

1. The Big One - Getting Ready

Getting Ready

  1. Reserve the computer lab.
  2. Make copies of “The Big One” handout.
  3. Make one copy of the “Big Quake Dates” handout per class (possibly on colored paper or cardstock paper) and cut it into strips with one time period per strip.
  4. Laminate the map if desired and hang it up near the front of the classroom.
  5. Set out remaining materials: Plexiglas, scotch tape, Monopoly houses, and color dots.

1. The Big One - Lesson Plan

Lesson Plan
What is an earthquake demo:

  1. Ask the students what they know about earthquakes. You can list their responses on the board.
  2. Tell students that you are going to demonstrate what causes an earthquake. Set the 2 piece of Plexiglas on the table side by side. Describe how the gap between the pieces represent a “fault” a crack on the Earth’s surface that is susceptible to suddenly giving way and moving. Don’t talk about tectonic plates yet since the students will soon discover their existence on their own! Simply refer to the pieces of Plexiglas as pieces of land with a fault in between.
  3. Lay a 6 inch piece of scotch tape along the fault line. Describe how the tape represents the rocks and soil along the fault that help hold the pieces together. Make the junction secure but don’t work too hard at taping the pieces together or you will have to push very hard to get the fault to slip.
  4. Optional: decorate the surfaces with Monopoly houses and pieces.
  5. Slowly and steadily push one piece of Plexiglas away from you while pulling the other piece towards you. Eventually the tape will give way and suddenly break free. Monopoly pieces may scatter.
  6. Discuss with your students what they observed, paying particular attention to the energy that is stored and suddenly released.

Computer research:

  1. Pass out the handouts and go over their assignment.
  2. Allow each student to pick one slip of paper with a time frame on it.
  3. Give students 35-45 minutes to complete their research on the website.
  4. Remind students that they should mark the location of each earthquake on their list on the map for homework if they didn’t finish it in class.

Plotting earthquake locations:

  1. Ask students to get out their handouts from the previous day.
  2. Explain the procedure for the day. Each student will share details about one of the earthquakes they researched (preferably the one they used as an answer to question #4 on their handout). Then they will be given some color dots to plot the location of each of their earthquakes on the large map. Different colors will represent earthquakes of different magnitudes (red is not used here since it will represent volcanic activity in the Plate Patterns activity).

    Magnitude Color
    5.9 or lower Blue
    6.0-7.9 Green
    Over 8.0 Yellow

  3. One by one, have students come up to the front of the room to present their earthquake. They should describe the date it occurred, the magnitude, the location, and the 3 facts they learned about it.
  4. After a student finishes, give him/her sticky dots to plot their earthquakes on the map. While they plot their information, another student can come up and describe their research. Regulate the flow so that no more than 2-3 students are plotting their data on the map at one time.
  5. When all students have gone and all the data is plotted on the map, discuss any patterns you see on the map as a class. The goal here is really to have the students relate what they learned about the causes of earthquakes from the demonstration to what they are seeing on the map. The faults are the lines of earthquakes. The large blank areas are like the pieces of Plexiglas and are called tectonic plates. Some questions to consider include:
    • Where are we? How many major earthquakes have occurred near us?
    • Are the earthquakes evenly distributed across the map?
    • What are the most active earthquake areas in the world?
    • What do the clusters of earthquakes look like? Do they cluster in patches or in lines?
    • Look at the magnitude information. Where do the biggest earthquakes take place?
    • Think back to the demonstration at the beginning of this lesson. Remember how earthquakes are caused when energy is suddenly released along a fault. Where are the big faults on the planet (think of it as an abstract dot-to-dot drawing)?
    • The Plexiglas represented large pieces of land bordered by faults. Geologists call these large pieces of land tectonic plates. Where are the tectonic plates? How can we use the earthquake data to find the edges of the plates?
    • Do ALL earthquakes happen at the edges of plates? (No.) What are some of the exceptions that don’t seem to fit the general pattern.
  6. Optional: Have students copy the patterns you discover onto their personal maps on the handout – defining the plate boundaries and faults in between.

 

1. The Big One - Assessment

Assessment

  1. Collect the handouts.
  2. Ask students to explain what causes an earthquake. Include both a short paragraph and a labeled picture.

Going Further

  1. Add information about earthquake depth to the student tables and the class map. The deepest earthquakes tend to take place on or near subduction zones.
  2. See if the location of volcanoes also matches the plate boundary lines. Add data about the mid-ocean ridges and identify plate boundary lines. See the Plate Patterns activity for details.
  3. Look at the earthquakes that didn’t line up on a plate boundary. What is happening there? Investigate the causes of earthquakes that didn’t occur on a plate boundary.
  4. Play with the “This Dynamic Planet” map which allows you to select certain types of data to display on a dynamically generated map. Some of the data types you can select are volcanoes, earthquakes of different magnitudes, impact craters, plate boundaries, latitude/longitude grids and more.

1. The Big One - Sources and Standards

Sources
The idea came from Eric Muller’s activity Locating Earthquake Epicenters. His lesson suggests plotting daily earthquake data but I wasn’t able to spend a few minutes a day on that. Instead I modified Eric’s activity to fit in a single class period.

For resources and additional background information on plate tectonics, see the sources section of the Plate Patterns lesson.

Standards
Grade 6
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
a. Students know evidence of plate tectonics is derived from the fit of the continents; the location of earthquakes, volcanoes, and midocean ridges; and the distribution of fossils, rock types, and ancient climatic zones.
d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.
e. Students know major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from plate motions.

Shaping Earth's Surface
2. Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment. As a basis for understanding this concept:
d. Students know earthquakes, volcanic eruptions, landslides, and floods change human and wildlife habitats.

Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
f. Read a topographic map and a geologic map for evidence provided on the maps and construct and interpret a simple scale map.

Grades 9-12 Earth Science
Dynamic Earth Processes
3. Plate tectonics operating over geologic time has changed the patterns of land, sea, and mountains on Earth's surface. As the basis for understanding this concept:
d. Students know why and how earthquakes occur and the scales used to measure their intensity and magnitude.

2. Plate Patterns

Summary
Kilauea Crater, Hawaii: Pu'u 'O'o crater at dusk. Image courtesy of USGS.Kilauea Crater, Hawaii: Pu'u 'O'o crater at dusk. Image courtesy of USGS.Starting with an earthquake epicenter map (generated by students in The Big One activity), students add information about where active volcanoes are located and the location of the mid-ocean ridges. With the combined information about volcanoes, mid-ocean ridges, and earthquake epicenters, students can trace the boundaries of the Earth’s major plates. On individual student maps containing earthquake epicenter data, they outline the plate boundaries, learn the names of each plate, and use colored pencils to highlight volcano zones and mid-ocean ridges. Future activities in this box have students adding plate direction and speed information to student maps as well as labeling 4 different types of plate boundaries: continent-continent convergent boundaries, subducting convergent boundaries, transform boundaries, and divergent boundaries. The direction and speed of many plates can be inferred from the opposition of mid-ocean ridges on one side of the plate and volcano zones on the other.

Objectives
Can recognize that the Earth’s crust is broken into large, independently moving pieces known as tectonic plates.
Can define the boundaries of the tectonic plates using data about the location of earthquake epicenters, active volcanoes, and mid-ocean ridges.
Can use latitude and longitude information to plot locations on a world map.

Vocabulary

Earthquake
Epicenter
Volcano
Mid-ocean ridge
Tectonic plate
Plate boundary

Attachment Size
2plate_patterns.doc 70.5 KB
volcano_list.doc 69 KB

2. Plate Patterns - Logistics

Time
20-30 min add volcano data to map
20-30 min learn about mid-ocean ridges and add them to the map
45-50 min trace and color code plate boundaries and label with the names of tectonic plates

Grouping
Individual

Materials

  • Copies of the USGS/NPS World Earthquake Map for each student (download a copy of the “World Earthquake Map” from the USGS/NPS website under PDF documents)
  • Overhead transparency version of the World Earthquake Map
  • 1 teacher copy of the USGS/NPS World Plates Map for reference (download a copy of the “Earth’s Tectonic Plates” from the USGS/NPS website under PDF documents)
  • 1 teacher copy of the Mid-Ocean Ridges Map for reference (print a copy from the USGS website).
  • Overhead projector
  • 4 colors of overhead projector pens
  • 1 copy of the Volcano List for the class, cut into strips with one line per strip.
  • Large world map used in The Big One activity (An alternative strategy is to use a copy of the “This Dynamic Planet” poster from the USGS, $14 + $5 handling).
  • Colored pencils or markers
  • Red 1/4” to 1/2” removable color dots (available in most stationary stores and drug stores for labeling maps and documents, each package usually contains 4 colors of dots: red, yellow, green and blue – only red is needed for this activity)
  • Masking tape or the somewhat less sticky blue or green painters’ tape
  • Optional: photos or a brief video clip of the mid-ocean ridges (see Sources section for good sources of images and videos)


Setting

Classroom

2. Plate Patterns - Background

Teacher Background
As early as the 1920’s scientists recognized that earthquakes lined up along fault zones and were not randomly scattered across the globe. The technology improved dramatically in the 1960’s when standardized seismic monitoring stations were established around the globe to police the ban on above-ground nuclear testing. The location of active volcanoes also lines up along these same zones. For example, the Pacific Ocean is surrounded by volcanoes and earthquake zones – commonly known as the “Ring of Fire”. These zones mark the boundaries of the Pacific Plate. Other tectonic plate boundaries may also be identified in this way.

Yet to see all the borders you also need to look under the ocean. In the late 1950’s, the exploration of the oceans revealed enormous mid-ocean ridges that zig-zag across the ocean floor between continents, nearly encircling the globe in places. These mid-ocean ridges rise on average 4,500 kilometers above the ocean floor and reach peaks higher than most mountains on land. More recent explorations have revealed that the mid-ocean ridges are characterized by huge upwellings of magma similar to volcanoes on land. Incredibly, life, in the form of archaebacteria and other species, exists along the mid-ocean ridges, surviving on the chemicals and nutrients exiting from hydrothermal vents.

Earth's Tectonic PlatesEarth's Tectonic PlatesCombining information from all these sources (earthquakes, volcanoes and mid-ocean ridges, it is possible to draw the boundaries of all the Earth’s major plates. The seven largest plates are easily identified: African Plate, Antarctic Plate, Eurasian Plate, Indo-Australian Plate, North American Plate, Pacific Plate, South American Plate. The smaller Philippine and Caribbean plates can be outlined using the prominent volcano and earthquake data. The Cocos and Nazca plates can be distinguished using mid-ocean ridge data.

Only the Juan de Fuca, Scotia, and Arabian plates are easily overlooked. In fact, I generally don’t emphasize these 3 plates if my students don’t identify them themselves since it is not essential to me that they memorize all the world’s tectonic plates, only that they recognize how the crust is broken into moving plates and that they understand how the plate boundaries can be determined with earthquake, volcano and mid-ocean ridge information.

Several critical questions remain:

  • Why are there earthquakes, volcanoes and ridges at the plate boundaries?
  • How come you don’t see earthquakes at the midocean ridges so much?
  • Why are there earthquakes but not volcanoes in the Himalayas above India?

All these questions are related to the differences in what is happening at each of the plate boundaries. (I choose to hold off on discussing these issues with my students until after they learn about the interior of the Earth, convection cells, and sea floor spreading.)

Plate boundaries may be divided into 3 main categories: convergent boundaries where plates collide, divergent boundaries where plate pull apart, and transform boundaries where plates grind past each other. Convergent boundaries in turn have different characteristics depending on if it is 2 pieces of continental crust colliding (continent-continent convergent boundary) or if 1 piece of oceanic crust is diving down below a piece of oceanic or continental crust (subducting convergent boundary).
Types of plate boundaries: Image courtesy of the USGS.Types of plate boundaries: Image courtesy of the USGS.

  • With divergent boundaries, like the mid-ocean ridges, Iceland, and the African rift valley, you get few earthquakes because the plates are pulling apart, not storing up energy as they collide or rub past each other. Instead, a gap forms between the plates and magma is pushed up from the mantle below to fill in the hole. Thus, you get lots of volcanoes, thermal vents, and great broken rifts in the earth.
  • With transform boundaries, like the San Andreas fault (most of other transform boundaries lie on the ocean floor), you get lots of earthquakes and only occasional volcanic activity. The plates are moving past one another and storing energy between them until the friction holding them together gives way in the form of an earthquake.
  • With subducting convergent boundaries, as in the northwestern edges of the Pacific Plate, the west coast of South America, and the northeastern edges of the Indo-Australian Plate, you get a combination of volcanoes and earthquakes. The lighter plate floats on top while another plate dives below the edge in a process known as subduction. As this occurs, the submerging plate melts and bubbles up through cracks in the overlying crust as volcanoes.
  • With a continent-continent convergent boundary, like the Himalayas at the boundary between the Indo-Australian and Eurasian plates, you get lots of earthquakes but very little volcanic activity. That is because both continental crusts are light and resist subduction. Instead, they buckle and crumple against one another, gradually rising skywards inch by inch. In fact, the Himalayas continue to rise at the rate of approximately 5 mm a year.

For ways to model these different plate boundaries with students, see the Sea Floor Spreading activity.

Student Prerequisites
Students should have participated in labeling and discussing the large classroom map with earthquake epicenter data. Students should already know that earthquakes cluster in lines along faults and that these faults occur at the edges of pieces of land that are colliding or grinding past one another.

2. Plate Patterns - Getting Ready

Getting Ready

  1. Make copies of the “World Earthquake Map” from the USGS/NPS website
  2. Make one copy of the Volcano List for each class, cutting them into strips with information about one volcano on each strip.
  3. Make a transparency version of the World Earthquake Map.
  4. Display the large map with earthquake data already plotted at the front of the classroom.
  5. Set out color dots and colored pencils.
  6. Print out reference sheets - Earth’s Tectonic Plates and Mid-Ocean Ridges Map.

2. Plate Patterns - Lesson Plan

Color coded and labelled world earthquake map: Original USGS earthquake epicenters map with mid-ocean ridges in orange, volcanic zones in red, and tectonic plate boundaries outlined in blue. See This Dynamic Planet website to download an unlabelled original.Color coded and labelled world earthquake map: Original USGS earthquake epicenters map with mid-ocean ridges in orange, volcanic zones in red, and tectonic plate boundaries outlined in blue. See This Dynamic Planet website to download an unlabelled original.

Lesson Plan
Volcano data

  1. Briefly review the patterns discovered by the students from the previous activity (The Big One).
  2. Pass out the volcano data strips and a single red color dot per student. Describe to them that their job is to read about their volcano and use the latitude and longitude information to plot the volcano on the map.
  3. One by one, have students come up to the front of the room to read the information about their volcano then plot their volcano on the map. While they plot their information, another student can come up and describe their volcano. Regulate the flow so that no more than 2-3 students are plotting their data on the map at one time.
  4. When all students have gone and all the data is plotted on the map, discuss any patterns you see on the map as a class. The goal here is have students recognize that volcanoes and earthquakes often line up along the same zones. Point out the ring of earthquakes and volcanoes that encircle the Pacific Ocean. This prominent zone is known as the “Ring of Fire”.

Mid-ocean ridges

  1. Describe to students that there are many volcanoes under the ocean. Briefly discuss the discovery and characteristics of the mid-ocean ridges. If available, show the students photos or a video clip of the bizarre life forms near the ridges and thermal vents.
  2. Refer to the Mid-Ocean Ridges Map and place masking tape on the class map where the mid-ocean ridges are located. Point out how the mid-ocean ridges nearly encircle the globe in places (such as going almost all the way around Antarctica) and how they cross land masses in 2 places – Iceland and East Africa.

Trace and color code plate boundaries

  1. Give each student a World Earthquake Map.
  2. Distribute the colored pencils so each student has at least 3 different colors available.
  3. Place your overhead copy on the projector.
  4. Select one color to represent the mid-ocean ridges. Set up a legend in one corner of the map and create a key showing that that color represents mid-ocean ridges. Refer to the large class map and trace the mid-ocean ridges in that color.
  5. Select another color to represent volcanic zones. Add that color to your key. Refer to the large class map and trace the volcanic zones. Some volcanoes (Kilauea in Hawaii, Mount St Helens in Washington, Vesuvius, Etna and Stromboli in Italy, and Erta Ale in Africa) don’t appear to have others nearby. Use a single dot of color to represent them if so desired.
  6. Select another color to outline the plate boundaries. Connect the dots and lines to trace the boundaries of the major tectonic plates. If students overlook the Juan de Fuca, Scotia, and Arabian plates, that’s OK. Also, the boundary between the North American and Eurasian plates is difficult to identify. If students insist on placing it through Alaska based on the earthquake evidence rather than through Russia as it truly lies, don’t be surprised and use your judgment as to whether to let them proceed with that error or not.
  7. Finally, label each of the plates with the name of each plate. If you wish, label the “Ring of Fire” as well.
  8. Turn these maps in or store them in a safe place for use in future lessons (such as the Sea Floor Spreading activity).

2. Plate Patterns - Assessment

Assessment

  1. Collect students’ color coded maps.
  2. Assign a plate puzzle as homework where students cut out, assemble, and label the Earth’s tectonic plates. My favorite tectonic plates puzzle is produced by the USGS/NPS. (download a copy of the “Plates Puzzle 1 and 2” from the USGS/NPS website under PDF documents).

Going Further

  1. Investigate and build models of different types of plate boundaries. See the Sea Floor Spreading activity and the Evidence for Plate Tectonics activity.
  2. Read excerpts from the booklet “This Dynamic Earth” which explains the theory of plate tectonics in greater detail. See the Sources section for how to get a copy.
  3. Research the recent discoveries of deep ocean life near the mid-ocean ridges.
  4. Use Google Earth to visit volcanoes and earthquake regions around the world! Download Google Earth then install volcano layers from the Smithsonian and visit the 1906 Earthquake in San Francisco courtesy of USGS.

2. Plate Patterns - Sources

Sources
Three excellent resources for more information on plate theory include:

  • The booklet, “This Dynamic Earth”, published by the USGS, is indispensable, providing all the background information a teacher could want and more. It can be downloaded in its entirety from the USGS website.
  • The poster and downloadable/printable handouts, “This Dynamic Planet”, provides maps and figures showing plate boundaries, volcanos, earthquake data, impact craters and more. The back of the map has excellent information on different types of boundaries, rock ages, hot spots and more. You can even download the data that was used to generate the map for further analysis.
  • The website “What on Earth is Plate Tectonics?” by the USGS and the National Parks Service. In very easy to understand language, the site walks the user through the composition of the Earth, plate tectonics theory, and Earth history in view of plate tectonics.

The list of active volcanoes, their locations, and information about each was taken from several sources. In addition to the 20 or so “most active volcanoes”, the others on the Volcano List are either famous (such as Mount Saint Helens), deadly (such as Mount Vesuvius and Mount Pelee), or are located among a string of other volcanoes (such as Mount Cleveland).

  • Latitude and longitude information was taken from This Dynamic Planet’s website.
  • The Smithsonian’s Global Volcanism Program provided most of the detailed information about the volcanoes with is incredible database of photos, eruption history and other data.
  • The Space Science and Engineering Center at the University of Wisconsin – Madison provided a list of the most active volcanoes in the world and has cool satellite images of each volcano.
  • John Search, a volcano photographer, documentary maker and tour guide also lists the worlds most active volcanoes on his website with lots of excellent pictures.

For information on life along the mid-ocean ridges, see:

  • The VENTS program sponsored by the National Oceanic and Atmospheric Administration researches deep sea hydrothermal vents and submarine volcanoes.
  • The BBC “Blue Planet” has a kids area that allows you to conduct virtual explorations of the life in the deep ocean.
  • The Smithsonian recently had an exhibition called “Ocean Planet”. It’s online resources have great information about the life at the mid-ocean ridges.
  • The “Blue Planet – The Deep”, episode 2 of the extraordinary BBC television series with David Attenborough, explores the life that exists in the deepest reaches of the ocean including the mid-ocean ridges. It is perhaps the most visually enthralling introduction to mid-ocean ridges that you can find.

Standards
Grade 6
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
a. Students know evidence of plate tectonics is derived from the fit of the continents; the location of earthquakes, volcanoes, and midocean ridges; and the distribution of fossils, rock types, and ancient climatic zones.
d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.
e. Students know major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from plate motions.

Shaping Earth's Surface
2. Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment. As a basis for understanding this concept:
d. Students know earthquakes, volcanic eruptions, landslides, and floods change human and wildlife habitats.

Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
f. Read a topographic map and a geologic map for evidence provided on the maps and construct and interpret a simple scale map.

Grades 9-12 Earth Science
Dynamic Earth Processes
3. Plate tectonics operating over geologic time has changed the patterns of land, sea, and mountains on Earth's surface. As the basis for understanding this concept:
d. Students know why and how earthquakes occur and the scales used to measure their intensity and magnitude.

3. Journey Through Earth

Summary
In the style of Jules Verne’s book Journey to the Center of the Earth, take your students on a walk, using sidewalk chalk to mark the boundaries between the different layers inside our planet. After you pass through each layer, tell your students about the layer of the Earth they just traveled through. This lesson was developed by Eric Muller of the Exploratorium Teachers’ Institute. Here you will find a student handout for taking notes during the walk, a teacher cheat sheet and some assessment ideas. Download a detailed lesson plan for this activity from Eric Muller’s website, originally published in The Science Teacher, September 1995.

Objectives

Can name and describe the different layers in the Earth.
Can appreciate the relative thickness of the various layers relative to familiar objects such as a human being or the tallest building.

Earth's Layers: Layers not drawn to scale. Image courtesy of Jeremy Kemp.Earth's Layers: Layers not drawn to scale. Image courtesy of Jeremy Kemp.Vocabulary
Inner core
Outer core
Mantle
Lithosphere
Crust

Attachment Size
3earth_journey.doc 45 KB
earth_journey_handout.doc 27 KB
earth_journey_teacher.doc 32.5 KB

3. Journey Through Earth - Logistics

Time
10 min introduction
35-40 min walk

Grouping
Whole class

Materials

  • A copy of the Earth Journey Handout for each student
  • A copy of the Earth Journey Teacher Cheat Sheet for yourself
  • A piece of sidewalk chalk for each student

Setting
Sidewalk around 2-3 city blocks (640+ meter loop)

3. Journey Through Earth - Background

Teacher Background
The earth is composed of many distinct layers. Their identity has primarily been inferred from seismic data and from analysis of the magma welling up out of volcanoes. A table of the various layers and a brief description of each follows (this same information is provided on the Earth Journey Teacher Cheat Sheet).

Layer Actual dist. from center  Description
Inner core 

0-1200 km

(6400-5200 km from surface) 

Metal (iron and nickel)
8,000-10,000˚C
3-5 million atmospheres of pressure
Solid – Even though the temperatures are tremendous, the pressure is also so tremendous that the inner core is squeezed into a solid state.
Outer core

1200-3500 km

(5200-2900 km from surface) 

Metal (iron and nickel)
2,000-1,000˚C
1-2 million atmospheres of pressure
Liquid – Since there’s less pressure, the outer core can flow as a liquid and its motion is thought to generate Earth’s magnetic field.
Mantle 

3500-6300 km

(2900-100 km from surface) 

Rock (magma)
1,000˚C
1 million atmospheres of pressure
Near-solid to liquid – Near the core, the mantle is a plastic solid, meaning that it is a liquid but it incredibly viscous and flows incredibly slowly. It becomes more liquid and less viscous as you move outward and the pressure decreases.
Lithosphere and crust

6300-6400 km

(100-0 km from surface) 

Rock and ocean
Very low temperature and pressure
Solid (except for the ocean)
The lithosphere forms the tectonic plates. The bottom of the lithosphere is technically still part of the mantle. Riding on top of the lithosphere is the crust, the layer we live on (between 5-70 km deep).

I structured the walk for 640 m since the calculations become very easy from the actual distances to the walk distance (and thus is easy for kids to see the relationship). In addition, if the 640 m walk is arranged in a loop, it is quite easy to fit the walk into a regular 45-50 minute period.

Student Prerequisites
None

3. Journey Through Earth - Getting Ready

Getting Ready

  1. Make copies of the Earth Journey handout.
  2. Make copy of the Earth Journey Teacher Cheat Sheet for yourself.
  3. Get sidewalk chalk.
  4. Pace out the entire walk to make sure your route is long enough.

3. Journey Through Earth - Lesson and Assessment

Lesson Plan
Download a detailed lesson plan for this activity from Eric Muller’s website.

Assessment
Have students complete the handout during the walk or afterwards. As you describe each part of the journey, students can label the borders between each layer and describe the composition, temperature, pressure, and physical properties of each layer on the handout.

Going Further

  1. Have students build a cutaway, to scale, model of the Earth using a Styrofoam ball. Cut away a quarter of the ball and use markers to color in each layer. Draw a map (possibly showing the tectonic plates) on the outer surface. Label the model by with pins attached to a short description on paper.
  2. Study the convection cells that take place in the mantle and that (partially) drive the movement of tectonic plates. See Convection in a Pan activity.
  3. Try the “Shadows from the Core” activity from the UC Berkeley Space Sciences Laboratory and discover how the deflections of seismic waves through the Earth gave researchers clues about the different composition and density of each of the Earth’s layers.
  4. Read Jules Verne’s Journey to the Center of the Earth (or excerpts from it). It’s a classic early science fiction novel.

 

3. Journey Through Earth - Standards

Standards
Grade 6
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
b. Students know Earth is composed of several layers: a cold, brittle lithosphere; a hot, convecting mantle; and a dense, metallic core.
c. Students know lithospheric plates the size of continents and oceans move at rates of centimeters per year in response to movements in the mantle.

4. Convection in a Pan

Summary
What drives the motion of the Earth’s tectonic plates? Partly, it is convection, the process by which heat energy is transferred by currents in a liquid or gas. Convection currents within the mantle carry tectonic plates along with the slowly moving mantle like giant rafts carried along by a current in a river. To help students understand this idea, soapy water in a pie pan is heated from below and convections currents can be observed forming and moving in the soapy water. Several prelude demonstrations help students recognize that hot things rise and cold things sink.

Objectives
Can recognize that hot things rise and cold things sink.
Can describe and explain the process of convection.
Can investigate and illustrate convection currents in a pan of soapy water.
Can correlate convection currents in the pan of water to convection currents in the Earth’s mantle.
Can diagram convection currents in the Earth’s mantle.

Vocabulary

Mantle
Lithosphere
Crust
Convection
Heat

Attachment Size
4convection_in_a_pan.doc 78 KB
convection_handout.doc 28.5 KB

4. Convection in a Pan - Logistics

Time
10 min demo and introduction
30-40 min investigation
10-15 min discussion

Grouping
Groups of 4-6 students

Materials
For the demo, the teacher needs:

  • One dry cleaner bag
  • Cellophane tape
  • 3-4 paper clips
  • Blow dryer (hand held hair dryer)


Each group of students needs:

  • One aluminum pie tin
  • Tea light candle, hot plate, or other heat source
  • Matches or a lighter
  • 4 film canisters
  • Food coloring in dropper bottles or with eyedroppers
  • 2-3 cups water
  • 2-3 tablespoons liquid hand soap or shampoo with a metallic, pearly appearance. SoftSoap® and Walgreen’s Liquid Soap both work well. Look for glycol stearate, glycol distearate or glycerol stearate among the ingredients on the label.
  • Small pocket-sized mirror

Every student needs a copy of the Convection in a Pan handout.

Setting
Classroom

4. Convection in a Pan - Background

Teacher Background
The earth has several major layers – a hot metallic core, a less hot liquid mantle, and the solid lithosphere and crust on top (see background section of Journey Through Earth for more information). The hot metallic core causes the mantle immediately above to heat up. As the liquid rock in the mantle heats up, it rises because a heated liquid (or gas) expands and becomes less dense than the cooler liquid (or gas) nearby. When this hot liquid reaches the top of the mantle layer, it gets pushed aside by more hot mantle rising below it, spreading out under the solid lithosphere above like a cloud of steam hitting the ceiling of the kitchen. As it spreads out, it cools. Cool liquids (and gases) shrink in volume and are more dense than the warmer liquids (or gases) nearby. Therefore, the cooled mantle sinks to the bottom of the mantle layer where it gets heated by the core and begins the cycle anew.

This process through which heat energy is transferred through currents within a liquid or gas is called convection. The cyclical nature of the process in an enclosed system like the mantle of the Earth results in convection cells – local regions of liquid or gas that form a relatively stable cycle (heating, rising, moving aside, cooling, and sinking in roughly the same location over and over again).

Convection in a pot of water: From Figure 32 of "This Dynamic Earth". Image courtesy of the USGS.Convection in a pot of water: From Figure 32 of "This Dynamic Earth". Image courtesy of the USGS.Convection takes place in many other systems. A pot of water boiling on the stove is a good example of convection. Watch spaghetti boiling in a large pot and you will see the noodles rise near the middle of the pot above the flames, spread out over the surface, and fall again near the edges where it is cool. In the Earth’s atmosphere, convection results in regional weather patterns and thermals (rising columns of heated air). Eagles and hang gliders both take advantage of thermals to stay aloft. In the Earth’s oceans, the warm ocean water near the equator tends to follow currents towards the poles while cold polar ocean water follow currents back again to the equator.

A key concept is that hot fluid and gas rises and cold fluid and gas sinks. To demonstrate this principle, you can create a hot air balloon in the classroom using a dry cleaner bag and a hand-held hair dryer.

Student Prerequisites
Students should have learned about the Earth’s layers. Ideally, they will also have learned about density and the relationship between temperature, volume, and molecular motion. However, this lesson is written assuming that students don’t know about density and heat yet.

4. Convection in a Pan - Getting Ready

Getting Ready

Test the hot air balloon demo

  1. Use cellophane tape to seal the top seam and any holes in the dry cleaner bag. Use as little tape as possible.
  2. Clip 3-4 paper clips around the bottom edge of the bag, as evenly distributed as possible. This will keep the bag upright and stable as it takes flight.
  3. Hold the bag at the top. Get helpers or use 2 chairs to keep the bottom edges open.
  4. Turn the blow dryer on at the lowest setting and hold it near the bottom of the bag (but not so close that the bag begins to melt). Allow the hot air to inflate the bag.
  5. When the bag is fully inflated, let go of it to test its buoyancy. If it lifts off, let it go. If it doesn’t, continue filling with the blow dryer for a little longer.
  6. Watch its flight, taking note of how stable it is in the air. When it lands again, adjust the paper clips to make it more stable. If it tilts one way, move them to different locations. If it flips over completely, add more paper clips. If it doesn't fly at all, remove some clips.

Set up the pie pans

  1. Make copies of the Convection in a Pan student handout.
  2. Each pie pan will need about 2-3 cups of water. In a large pitcher or bucket, fill the bucket with as much water as you need for all the groups (plus a few cups extra).
  3. The dilution of soap to water is approximately 1 tablespoon soap to 1 cup water. Add the appropriate amount of soap to the water.
  4. Mix the soap into the water gently, trying to minimize the number of bubbles. The final solution should be very fluid and should leave swirly trails as you move your spoon or hand through the solution.
  5. Set the materials for each group into a pie pan: candle, 4 film canisters, matches, food coloring droppers.

4. Convection in a Pan - Lesson Plan

Lesson Plan
Hot air balloon demo

  1. Start class by asking for 4 volunteers.
  2. Have 1 volunteer hold the top of the pre-tested bag with paper clips attached and 2 others to hold the bottom edges open.
  3. Have the third volunteer turn on the blow dryer to the lowest setting and hold it under the opening. Make sure the blow dryer isn’t too close to the opening that it melts the bag or overheats your volunteers hands.
  4. As the bag fills, have the other students predict what will happen.
  5. When the bag is full, have the blow dryer volunteer turn the dryer off.
  6. On the count of three, have the other 3 volunteers let go and watch the balloon fly.
  7. When the bag finally comes back down, discuss what happened. Some questions to consider include:
    • Why did the bag fly? What powered it?
    • How is the hot air balloon the same or different than a helium balloon? Was helium used?
    • What would happen if we used a regular fan blowing room temperature air into the bag? Why?
    • What would happen if we let an air conditioning vent fill the bag? Why?
    • Where is it hottest above a fire – directly above the flames or an equal distance to the sides of the flame? Why?
    • What happens to the steam above a pot of boiling water? Where does it go? Why?
    • If hot air rises, what do you think will happen to cold air?
    • Do you think this happens in a liquid? Do you think hot water will rise among cooler water? How about in a solid?

Convection in a pan exploration

  1. Tell students that they are going to watch what happens when a candle is placed under a pan of soapy water. Get the students into groups and assign each a work area to assemble around.
  2. Have one member of each group get a pie pan and the other needed materials.
  3. For the candle version of the activity, spread out the 4 film canisters on the table. Place the pie pan on top. It should look like a circular table on peg legs.
  4. Go around to each group and fill each pan a little more than half full with soapy water. Tell the students what is in the water to make it pearly. Ask them not to touch the surface so that the liquid can settle and fluid motion can cease.
  5. Pass out the handouts. Tell students that they are going to light the candle and put it under the pan. Something will happen to the liquid. Explain that their job is to carefully watch the liquid and draw arrows on the diagrams in the handout to show how the liquid is moving in different places.
  6. When the water in the pans are still, have students light the candle and slip it underneath the pan, right in the center.
  7. Have students watch what happens. The food coloring is a tool that can help them figure out what is going on by placing a drop in different places around the pan and watching how the coloring moves away from that spot.
  8. Let the students experiment, discuss and draw for up to 10 minutes then blow out the candles. After 10 minutes or so, the water in the pan will begin to get too hot and the pearlescent molecules (glycol stearate) will begin to break down.
  9. Give students a little more time to finish their drawings.
  10. Optional: See the variations suggested in the going further section.
  11. Clean up and dispose of the soap solution down the sink (or save it for the next class).
  12. Discuss the students’ observations of convection currents together as a class. Together, draw 3 different views of the fluid motion on the board (top view, bottom view, and side view.
  13. Mantle Convection: Figure 32 from "This Dynamic Earth". Image courtesy of the USGS.Mantle Convection: Figure 32 from "This Dynamic Earth". Image courtesy of the USGS.Relate this activity to what the students saw with the hot air balloon. Hot air rises. So how does that relate to what is going on in the pie pan? My students found it helpful to label the side view drawing of the pie pan convection cells with labels describing what is happening at every place. (For example, label the water right above the candle in the center “Water near candle flame gets hot.” Label an arrow rising from the candle to the surface “Hot water rises.” Etc.)
  14. Discuss what is going on in the mantle of the Earth. On the board, draw a cross section through the Earth like the diagram shown. Relate this picture to the convection cells observed in the pie pan. Show how the super hot core of the Earth is like the candle heating the mantle above it until the hot mantle rises towards the surface of the Earth.
  15. Optional: Discuss other examples of convection in the Earth’s atmosphere and oceans.

4. Convection in a Pan - Assessment

Assessment

  1. Collect the students’ handouts and drawings.
  2. In teams, have students predict what would happen in the following scenarios.
    • You put a pot of cool water on the stove. You turn on the flame below the pot. The water at the bottom of the pot nearest the flame begins to get hot. Will convection currents be created? If so, diagram them, showing how the convection currents would move through the water. If not, explain why not.
    • You have a pot of cool water sitting on the table. You turn on a heat lamp above the pot. The water at the top of the pot nearest the heat lamp begins to get hot. Will convection currents be created? If so, diagram them, showing how the convection currents would move through the water. If not, explain why not.
    • You close all the windows and doors of the classroom. You set a portable camping stove on the floor in the middle of the room and turn the burner on. The air near the burner gets hot. Will convection currents be created? If so, diagram them, showing how the convection currents would move through the air in the room. If not, explain why not.
    • You have a rectangular pan full of water. You balance the pan on a pedestal. Under one end of the pan you light a candle. The water near that end gets hot. Under the other end of the pan you place a large pot of ice water. The water near that end gets cold. Will convection currents be created? If so, diagram them, showing how the convection currents would move through the water. If not, explain why not.
    • Think about the Pacific Ocean. The water near the equator is warmed by the sun. The water near the North and South Poles gets less direct sunlight and is very very cold. Will convection currents be created? If so, diagram them, showing how the convection currents would move through the water. If not, explain why not. (Hint, look at your answer to the previous question.)

Going Further

  1. Try the following variations:
    • Try the activity with multiple candles.
    • Sprinkle baby powder on the surface and watch the particles move.
    • Use tinfoil to shape a small, flat foil raft to represent tectonic plates. Place one or more rafts on the surface of the pan with the candle lit to model the movement of tectonic plates. (Aluminum foil works better than Styrofoam and plastic since multiple rafts will not stick to one another through static forces, and if shaped with an out-turned lip, will not stick to one another through surface tension either).
    • Once the solution is hot (has been used for 10 minutes), blow out the candle and put a piece of ice in the middle of the liquid.
    • Once the solution is hot, very carefully pick the whole pan up and set it down on a cool table.
    • Once the solution is hot, carefully slide a fifth film canister full to the brim with ice water under the pan. The surface of the ice water should contact the bottom of the pan.
    • Try the activity with a candle at one end next to a fifth film canister full to the brim with ice water a little distance away.
  2. This lesson does not discuss the relationship between temperature and volume or the concept of density. The only concept students are expected to understand is that hot things rise and that cold things sink. So study into these other concepts.
  3. Try the variation of this activity used in a UC Museum of Paleontology teacher workshop. They use a rectangular baking dish full of water with a heat source at one end and a bucket of ice water at the other.

4. Convection in a Pan - Sources and Standards

Sources
The activity elaborates upon one of the Exploratorium’s science snacks “Pie Pan Convection”.

The hot air balloon demonstration was taken from a lesson by Gregory Vogt, edited by Roger Storm of the NASA Glenn Research Center. See their lesson plan for detailed information, diagrams and tips.

A great resource for learning more about heat, density and convection is the  first session of a UC Museum of Paleontology teacher workshop. There are excellent, detailed descriptions of heat, density and convection concepts as well as teaching tips and resources.

Standards

Grade 6
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
b. Students know Earth is composed of several layers: a cold, brittle lithosphere; a hot, convecting mantle; and a dense, metallic core.
c. Students know lithospheric plates the size of continents and oceans move at rates of centimeters per year in response to movements in the mantle.

Heat (Thermal Energy) (Physical Sciences)
3. Heat moves in a predictable flow from warmer objects to cooler objects until all the objects are at the same temperature. As a basis for understanding this concept:
a. Students know energy can be carried from one place to another by heat flow or by waves, including water, light and sound waves, or by moving objects.

Energy in the Earth System
4. Many phenomena on Earth's surface are affected by the transfer of energy through radiation and convection currents. As a basis for understanding this concept:
c. Students know heat from Earth's interior reaches the surface primarily through convection.
d. Students know convection currents distribute heat in the atmosphere and oceans.

Grades 9-12 Earth Science
Energy in the Earth System
5. Heating of Earth's surface and atmosphere by the sun drives convection within the atmosphere and oceans, producing winds and ocean currents.

5. Seafloor Spreading

Summary
Students take what they know about earthquake, volcano and mid-ocean ridge distributions (The Big One and Plate Patterns) and put it together with what they know about convection in the Earth’s mantle (Journey Through Earth and Convection in a Pan). They revisit what they know about how earthquakes are created, by the sudden release of energy as plates collide or rub together (but not so much when they split apart). They look for patterns in their world maps, observing that mid-ocean ridges and dense earthquake/volcano zones tend to lie on the opposite side of plates. With this information, they can infer the direction that the plates are moving. Next students build a model illustrating seafloor spreading and discuss the magnetic and seafloor age data that support this model. Finally, students codify the different types of plate boundaries, describing the various features and characteristics of each.

Seafloor Spreading: Animation created by the US Geological Society.Seafloor Spreading: Animation created by the US Geological Society.Objectives
Can find patterns on a map and use that information to infer the direction of plate motion.
Can diagram and explain what causes earthquakes and volcanoes.
Can build and interpret a physical model of seafloor spreading.
Can describe some of the evidence supporting seafloor spreading.
Can describe the characteristics of the 3 major classes of plate boundaries as well as differences between subducting convergent boundaries and continent-continent convergent boundaries.

Vocabulary
Seafloor Spreading with Magnetic Reversals: Animation courtesy of the US Geological Society.Seafloor Spreading with Magnetic Reversals: Animation courtesy of the US Geological Society.Mantle
Lithosphere
Crust
Earthquake
Volcano
Mid-ocean ridge
Tectonic plate
Oceanic plate
Continental plate
Seafloor spreading
Convergent boundary
Divergent boundary
Transform boundary
Subduction
Island arc

Attachment Size
5sea_floor_spreading.doc 67.5 KB
sea_floor_model.doc 402.5 KB
sea_floor_model.pdf 697.86 KB

5. Seafloor Spreading - Logistics

Time
30-50 min hypothesize plate motions
20-25 min build seafloor spreading models and discuss evidence
30-35 min study models and describe types of plate boundaries

Grouping
Inferring the direction of plate motion will occur in groups of 2 or 3. Making models of seafloor spreading takes place individually.

Materials

  • Cardstock paper
  • Copy of Seafloor Spreading Model Pieces on cardstock for each student
  • Colored pencils
  • Stapler
  • Scissors
  • Students’ color coded World Earthquake Maps from Plate Patterns lesson
  • Large labeled world map from Plate Patterns lesson or a copy of the “This Dynamic Planet” poster from the USGS, $14 + $5 handling 
  • Optional: Pictures, animations or other information showing seafloor spreading, magnetic survey maps of the ocean floor, or age maps of the ocean floor (see sources section for resources).


Setting

Classroom

5. Seafloor Spreading - Background

Teacher Background
Seafloor spreading is one of the most critical pieces of evidence in the development and support of the theory of plate tectonics. It is through this process that new oceanic crust is formed along the mid-ocean ridges as oceanic plates diverge and separate. Magma wells up into the gap, hardens, and forms new crust. As the plates continue to separate, these newly formed pieces of oceanic crust separate and make room, gradually moving outward away from the mid-ocean ridges at the rate of a few centimeters per year.

Subduction zone diagram: Image courtesy of USGS.Subduction zone diagram: Image courtesy of USGS.After several million years of this slow journey away from the mid-ocean ridges, the oceanic crust collides with a different tectonic plate in a process known as subduction. If the oceanic crust meets continental crust, the denser oceanic crust is forced under the continental crust. If the oceanic crust meets oceanic crust, then one or the other will be forced below the other. In these subduction zones, earthquakes are common due to the build up and sudden release of energy at the junction. Also, as the oceanic crust dives down below the other plate into the mantle, the old plate melts, forming a pool of magma that is forced back up through the crust above as volcanoes on the continent or a chain of volcanic islands on one side of the subduction zone.

In some instances, some continental crust is riding along on the oceanic plate and collides into another piece of continental crust. This is currently taking place in the Himalayas and was part of the process that created California (see the background section of Making California for more details). At these continent-continent convergent boundaries, the two sections of continental crust ram into one another, causing the crust above to buckle and fold into tall mountain ranges (the Himalayas and the Sierra Nevadas).

Using these patterns, students can infer both the direction and the relative speed each tectonic plate is moving. The following table shows all the plates and their approximate direction and speed.

 Tectonic Plate  Approximate direction  Approximate velocity (cm/year) 
 African  W  1.62
 Antarctic  SW  2.21
 Arabian  NW  2.24
 Australian  N  5.81
 Caribbean  W  3.03
 Cocos  NE  11.57
 Eurasian  W  2.52
 Indian  N  2.59
 Juan de Fuca  NE  10.45
 Nazca  E  3.59
 North American  W  4.11
 Pacific  NW  11.78
 Phillippine  NW  10.57
 Scotia  W  4.89
 South American  W  4.83

Age of the seafloor: Red indicates newly formed crust. Blue indicates oldest oceanic crust. Image courtesy of National Oceanic and Atmospheric Administration.Age of the seafloor: Red indicates newly formed crust. Blue indicates oldest oceanic crust. Image courtesy of National Oceanic and Atmospheric Administration.This table was created using the Rice University Plate Motion Calculator. For further information on the types of plate boundaries, see the background section of the Plate Patterns lesson.

The ultimate cause of sea floor spreading (and the theory of plate tectonics as a whole) is still debated in the scientific community. Some argue that it is driven by convection currents in the mantle. Others argue that the upwelling of magma and creation of new crust at mid-ocean ridges pushes the older crust out of the way (the “Ridge Push” theory). Others argue that the sinking of the old crust at subduction zones drags the oceanic crust along behind it (the “Slab Pull” theory).

Student Prerequisites

Students should have created or studied a map with data about earthquake, volcano and mid-ocean ridge locations. Students should know that the Earth’s crust is divided into large plates the size of continents or oceans. Students should know about convection currents in the Earth’s mantle and should understand how those could affect the motion of the tectonic plates above.

5. Seafloor Spreading - Getting Ready

Color coded and labelled world earthquake map: Original USGS earthquake epicenters map with mid-ocean ridges in orange, volcanic zones in red, and tectonic plate boundaries outlined in blue. See This Dynamic Planet website to download an unlabelled original.Color coded and labelled world earthquake map: Original USGS earthquake epicenters map with mid-ocean ridges in orange, volcanic zones in red, and tectonic plate boundaries outlined in blue. See This Dynamic Planet website to download an unlabelled original.

Getting Ready

  1. Make a copy of the Seafloor Spreading Model Pieces on cardstock paper for each student
  2. Set out scissors and colored pencils
  3. Remind students to bring their color coded World Earthquake Maps from Plate Patterns lesson
  4. At the front of the room display the large labeled world map from Plate Patterns lesson or a copy of the “This Dynamic Planet” poster from the USGS

5. Seafloor Spreading - Lesson Plan

Lesson Plan
Infer plate motion

  1. Review convection currents in the Earth’s mantle. Discuss how convection currents form and how they move. (The heat from the core causes mantle in some areas to rise while cooled mantle near the crust sinks.)
  2. Discuss how things floating on top of the surface of this mantle move. (At the surface, stuff just above the places where hot mantle rises gets pushed away from each other and stuff where the cool mantle sinks gets pulled down or pushed against the edge of something solid.)
  3. Tell students you are going to switch gears briefly.
  4. Review the causes of earthquakes. Discuss how earthquakes are caused when two plates collide or rub against one another. For a while, the plates get stuck even though the pressure is building up all the time and finally, when the plates release, you get an earthquake.
  5. Discuss how speed might affect the number of earthquakes. Would you expect more earthquakes each year if 2 plates collide at high speed or at low speed?
  6. Discuss whether earthquakes would be expected where plates are separating. (Not so much.)
  7. Put it together. So, the Earth’s surface is made up of plates riding along on convection currents in the mantle. The plates are moving in all different directions. In some places the will collide head on. In some places they will rub against one another going in opposite directions. Where they collide or rub, you’ll get lots of earthquakes. In some places they will separate from one another. Where the separate, you’ll get much fewer earthquakes.
  8. Ask students to get out their color coded World Earthquake Maps.
  9. Tell them that their job, in teams of 2 or 3, is to see if they can figure out which direction each plate is moving using the information on their maps (earthquake epicenter locations, volcano zones, mid-ocean ridge locations). Their job is to draw an arrow in pencil on each plate showing the direction that plate is moving. If they believe a plate is standing still, then don’t draw anything at all. If you want to give a hint, tell them to start with the Pacific plate or the Nazca plate and go from there.
  10. Give students 10-20 min to discuss their maps and make hypotheses. Not that the Eurasian and African Plates don’t fit the pattern as well because they
  11. Different groups will figure out the patterns at different rates. For those groups that finish early, have them modify the length of their arrows to show the speed of the plates. For instance, a fast moving plate should have a very long arrow while a slow moving plate should have a short arrow.
  12. When most groups have finished, bring the focus of the class up to the large map at the front of the classroom. One by one, go through the plates (starting with the Pacific and Nazca plates) discussing what direction they inferred the plate would move and why. Students should correct their personal maps if there are any errors.
  13. Optional: when all the direction information has been added, see if students can figure out how fast each plate is moving. Use the length of the arrow to represent speed.


Seafloor spreading model

  1. On the students’ labeled World Earthquake Maps have them focus on a diagonal rectangular strip starting at the South American plate, crossing west over the Nazca and Pacific Plates, past Hawaii, and ending in the earthquake/volcano zone on the right edge of the Phillippine Plate and Korea.
  2. Tell students that they will be building a model of this region today.
  3. Pass out the Seafloor Spreading Model pieces, the scissors, staplers, and colored pencils.
  4. Begin with the page with the diagram cut-through view of the mantle showing convection currents. Fold the paper lengthwise along the fold line “hot dog style”. Focus on the large diagram for now.
  5. Label the diagram (mantle, mid-ocean ridge, lithosphere, oceanic crust, continental crust, island arc, volcanoes, ocean, convection currents, etc.)
  6. Color the diagram in.
    • Use blue to represent the ocean.
    • Use one color to represent the left-most oceanic crust with the volcanic island arc.
    • Use another color to represent the two slabs of oceanic crust in the middle spreading outward from the mid-ocean ridge.
    • Use another color to represent the continental crust on the far right.
    • Use a bright color like orange or red to represent that magma in the mantle and welling up through the volcanoes.
  7. Now describe that the big diagram is the side view while the other part on the other side of the fold is the top view. Drape the model over the edge of the table with the large diagram hanging over the side to get everyone oriented.
  8. Next label and color the top of the model so that they match the colors on the cut-through view.
  9. Use the scissors to cut a slit along each of the dark black lines on the top of the model. Do not cut all the way to the edge. It helps to make a light fold perpendicular to the line and make a small snip with the scissors to get the cut started. Then you can open the paper up to cut the rest of the line.
  10. Now take the other piece of the model (the piece of paper with all the grey stripes). Cut out the grid along the outer lines and throw the edges away.
  11. Cut the two strips apart lengthwise down the middle “hot dog style”.
  12. Put the two strips together, one on top of the other with the writing on the inside, facing one another.
  13. Glue or staple the two strips at the end that says “Glue this end to other strip”.
  14. Feed the stapled/glued end into the slit labeled “mid-ocean ridge”.
  15. Feed the free end of the left hand strip into the subduction zone on the left.
  16. Feed the free end of the right hand strip into the subduction zone on the right.
  17. Hold a free end in each hand and slowly pull the strips of paper through the subduction zones. “New” ocean crust should appear at the mid-ocean ridge. Pull down at the mid-ocean ridge to reset the model.
  18. Point out the divergent and convergent boundaries on the model.
  19. Once the models have been built, discuss what the white/grey stripes represent – magnetic reversals recorded in the rock on the ocean floor in the form of tiny pieces of iron, aligned with the Earth’s magnetic field.
  20. Discuss what the age markers mean – the ocean floor nearest the mid-ocean ridges are youngest and the ones nearest the subduction zones are oldest.
  21. Point out the mirror-image symmetry on each side of the mid-ocean ridge and how that provided the first strong evidence to scientists that seafloor spreading actually takes place. (Now GPS (global positioning systems) can measure the creep of the plates in millimeters per year, corroborating the evidence trapped in rocks on the ocean floor.)
  22. Refer back to the labeled World Earthquake Map and the Pacific/Nazca plate boundary area, pointing out the relationship between the map and the model. Notice how subduction zones tend to have lots of earthquakes and volcanoes. If the subduction zone is in the ocean (like the Alaskan Aleutian Islands, the Philippines, the South Pacific Islands, and the Caribbean Islands), a chain of volcanic islands forms (a volcanic island arc). If the subduction zone is on the edge of a continent (like Central America and South America), a volcanic mountain range is pushed up on the continent.
  23. Finally, discuss the 2 plate boundaries that are not shown in this model: transform boundaries and continent-continent convergent boundaries. Use 2 pieces of paper to have each student model these boundaries.
  24. For a transform boundary, slide the 2 pieces of paper past each other, one moving up, and one moving down. Explain how this is similar to what is happening at the edge of California along the San Andreas fault. Notice on the World Earthquake map how transform boundaries tend to have lots of earthquakes but few volcanoes.
  25. For a continent-continent convergent boundary, slide the two pieces of paper into one another on the table top but don’t let one piece slide below the other like subduction. Instead, the 2 pieces of paper should collide and then buckle, each piece wrinkling up off the table. Explain how this is similar to what is happening at the top of the Indo-Australian plate where India has rammed into the Eurasian Plate. Notice on the World Earthquake Map how continent-continent convergent boundaries have lots of earthquakes and huge mountain ranges.

5. Seafloor Spreading - Assessment

Assessment

  1. Ask students to answer the following questions for each of the 4 types of plate boundaries described in this lesson:
    • Describe how the plates are moving.
    • Give an example of somewhere in the world where you can find this kind of boundary.
    • Are there earthquakes?
    • Are there volcanoes?
    • Is there a mid-ocean ridge?
    • Draw a labeled diagram of this type of boundary from a side view (like the large diagram on the model) showing the plates, the mantle below, and arrows to show what direction the plates are moving.
  2. For each of the following places in the world, name the type of boundary that the place is located on. If the place is not on a plate boundary, name the tectonic plate the place is located.
    • Nepal is a country high in the Himalayas, near the northern border of India. Nepal’s landscape is known for dramatic, tall mountain ranges and beautiful secluded valleys. There are many earthquakes.
    • Martinique is a tropical paradise in the Eastern Caribbean with lush rainforests and white sand beaches. The island is dominated by two currently dormant volcanoes, Mount Pelee and Carbet.
    • The Red Sea is a long, narrow inlet off the Indian Ocean, between Africa and Saudi Arabia. Currently, at its widest point, the sea is 190 miles across but it is slowly getting wider by a few centimeters each year.
    • Where you live.

Going Further

  1. Study other evidence for plate tectonics besides sea-floor spreading such as the fit of the continents and fossil evidence. See the Evidence for Plate Tectonics lesson.
  2. Study the amazing life forms found at mid-ocean ridges. See the sources section of the Plate Patterns lesson for detailed resources.
  3. Create a travel brochure of the geological features and geologic history of some of the worlds most famous plate boundaries. See the Plate Boundaries Around the World lesson for more details.

5. Seafloor Spreading - Sources and Standards

Sources
This activity combined the ideas from 1) a simple paper Seafloor spreading model by Ellen Metzger and 2) a more detailed shoebox Seafloor spreading model by John Lahr. Both lesson plans provide excellent background information and excellent alternative models.

The best resources for more information on Seafloor spreading can be found at:

  • This Dynamic Earth has an excellent section on how the theory of plate tectonics was developed using ocean floor data.
  • The Wikipedia articles on seafloor spreading and subduction provide excellent, concise summaries as well as beautiful images.
  • The animations on the front page of this lesson were created by the USGS. Other plate tectonics related animations may be found on their website.

The table of plate motion was created using the Rice University Plate Motion Calculator.

Standards
Grade 6
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
a. Students know evidence of plate tectonics is derived from the fit of the continents; the location of earthquakes, volcanoes, and midocean ridges; and the distribution of fossils, rock types, and ancient climatic zones.
b. Students know Earth is composed of several layers: a cold, brittle lithosphere; a hot, convecting mantle; and a dense, metallic core.
c. Students know lithospheric plates the size of continents and oceans move at rates of centimeters per year in response to movements in the mantle.
d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.
e. Students know major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from plate motions.
f. Students know how to explain major features of California geology (including mountains, faults, volcanoes) in terms of plate tectonics.

Project - Earthquake Towers

Earthquake TowerEarthquake TowerSummary
In this project, students construct drinking straw towers that must withstand the shaking of a shake table. One by one, 250 gram sandbags are loaded onto the towers. The towers must remain standing for 1 minute from the start of the simulated earthquake. Students then have 2 minutes to repair any damage before another sandbag is loaded and the next earthquake test begins. Students quickly learn basic principles of earthquake engineering and architecture as well as the team skills that are a basic part of all science and engineering fields.

Objectives
Can understand basic principles of earthquake engineering and design including the importance of a solid foundation, wide base, symmetrical design, and trusses.
Can work together in a team to design and build a structure.
Can follow through a design process of repeated designing, testing, redesigning and retesting a structure.

Vocabulary
Foundation
Height-base ratio
Symmetry
Truss

Attachment Size
proj_quake_towers.doc 46.5 KB
towers_handout.doc 36 KB

Towers - Logistics

Time
At least 2 hours to build structures and 5 minutes to test each one.

Grouping
Groups of 2-4 students.

Materials
Each group of students needs:

  • 1 cardboard base (approximately 25 cm by 25 cm)
  • 30 straws
  • 100 paper clips (one box)
  • 20 straight pins
  • 2 meters of string

The class needs:

  • 10-20 sandbags consisting of 250 grams sand in a sandwich sized ziplock bag. The bag should be taped into a sausage shaped cylinder for rigidity and ease of mounting onto the towers.
  • 1 earthquake tower testing platform with a movable platform connected to a rigid frame by rubber bands, springs, or a motor. Several designs may be found in the Sources section.
  • 4 large binder clips to secure the cardboard bases to the shake table platform.

Setting
Classroom

Towers - Background

Teacher Background
I found this to be a great end of the year project when the kids are wiggly and not able to focus anymore on bookwork. They thoroughly enjoy the competitive nature of the challenge and get very involved in designing, building and redesigning their structures.

The student handout provided gives the criteria that I assigned to my students as well as a grading rubric. Briefly, the structures must meet the following requirements:

  • The building must fit on the base.
  • The building must be at least 36 cm tall.
  • The building must have 2 stories that are each at least 18 cm tall (approximately the height of 1 straw).
  • Each story must support the weight of at least 1 sand bag (250 grams) without collapsing.
  • A construction drawing with measurements and analysis must be submitted before earthquake testing.
  • To survive an earthquake test, the building must not collapse for 10 seconds after the earthquake begins. The weights must stay on the building.

I observed the structure after each stage of testing described below. If at any point the structure buckled to the point that the sandbags fell off or dropped by more than halfway to the ground (a sandbag on the first story 18 cm high can fall as much as 9 cm and still be considered passing while a sandbag on the second story 36 cm off the ground can fall 18 cm) the structure was considered to have failed that stage of testing. Students had 2 minutes to repair any damage to their structure between each stage of testing although no new straws or materials could be provided.

  1. Place 1 sandbag on the first story.
  2. Place 1 sandbag on the second story.
  3. Minor earthquake with 1 sandbag on the top story. I designated that moving the platform horizontally to the side so that it touched the frame started a minor earthquake. No vertical motion was involved.
  4. Major earthquake with 1 sandbag on the top story. I designated that moving one corner of the platform so that it touched the corner of the frame as well as the table below started a major earthquake, leading to both horizontal and vertical motion.
  5. Major earthquake with 1 sandbag on the top story and 1 sandbag on the first story.
  6. Major earthquake with 2 sandbags on the top story and 1 sandbag on the first story.
  7. Major earthquake with 2 sandbags on the top story and 2 sandbags on the first story.
  8. Continue major earthquakes adding 1 sandbag at a time, first to the top story, then to the first story.

The best structure in my classes survived until a major earthquake with 4 sandbags on the top story and 3 sandbags on the first story.

Student Prerequisites
None, although the activity fits well among the seismology lessons.

Towers - Lesson Plan

Getting Ready

  1. Build your earthquake shake table (See Sources section).
  2. Prepare the sand bags.
  3. Do a trial run with a structure of your own design to see where students may run into trouble. Securing the structure to the foundation and securing the joints are two areas where students run into trouble.

Lesson Plan

  1. Introduce the project to the students.
  2. Explain the rules and requirements.
  3. Demonstrate the testing procedures and show how the shake table works.
  4. Show students some of the different methods for joining straws together without folding the straws and compromising their integrity.
  5. 2 straws may be pinned together with a straight pin.
  6. A paper clip may be partly opened up – the inner U pulled out from the outer U – and each U may be slipped into a different straw.
  7. Holes may be drilled with the pins and the string slipped through to tie straws together.
  8. Allow students to begin designing and building.
  9. Interrupt class at once or twice a class period for 5 minute “teaching commercials” based on various successful student designs or to combat problems multiple teams may have encountered. Some of the teaching commercials I included were:
  • Strategies for how to secure the structure to the foundation using paper clips, pins and/or string.
  • Would a better structure have a wide base of a narrow base?
  • Would a better structure be symmetrical or asymmertrical?
  • A description of trusses and cross-bracing and discussion of their use in bridges, earthquake retrofitting, and other structural engineering.
  • How can you secure the sand bags so that they don’t fall off?
  1. Test the structures. I chose to have students test their structures as they finished. This allowed for groups to work at different paces and reduced the overall number of days the students spent on this project. Another option is to require all teams to finish building on the same day so that testing could occur on the following day. In this way, all students can watch the others and make observations about the different structures, noting what worked and what didn’t.

Towers - Sources and Standards

Sources
This activity was inspired by the WGBH production of “Structures”, produced and narrated by Bebe Nixon. In this video designed to introduce teachers to inquiry-based teaching methods, students build towers and bridges out of drinking straws and see what is the maximum amount of weight each tower or bridge can hold. I adapted this lesson as a complement to the plate tectonics unit.

Shake TableShake TableTo create your own very simple earthquake table that is more like a trampoline than a standard, motor controlled earthquake table:

  1. Cut a piece of board or plywood into a 12” square. If you wish, create a raised edge for your platform by nailing lengths of 1/2” square dowel on top of each of the sides.
  2. Mount wood screws on the under side of the plywood at each corner and at the center of each side. Don’t screw the screws in all the way, make sure at least 1/4” sticks up so you can loop a rubber band around it.
  3. Construct a frame out of 2” x 4”s that fits around the wood square with around 1/2” clearance between the outer edge of the square and the inside edge of the frame. Make sure the 2” x 4”s are oriented so that the frame is 4” high.
  4. Mount wood screws on the top edge of the frame at each corner and at the center of each side. Again, don’t screw in the screws all the way.
  5. Loop a rubber band around each pair of screws so that the plywood square is suspended like a trampoline within the frame.

Other earthquake table designs powered by an electric drill are described by John Lahr.

A great, very accessible resource on structural engineering principles with projects that can be adapted for the classroom is the book The Art of Construction: Projects and Principles for Beginning Engineers and Architects by Mario Salvadori, Chicago Review Press (1981).

Standards
Grade 6 – Earth Science
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.
e. Students know major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from plate motions.

Shaping Earth's Surface
2. Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment. As a basis for understanding this concept:
d. Students know earthquakes, volcanic eruptions, landslides, and floods change human and wildlife habitats.

Sub Plan - Earthquake Fingerprints

Summary
Seismogram: Image created by Crickett.Seismogram: Image created by Crickett.Using the excellent Virtual Courseware - Earthquake program, students learn how to read a seismogram and use them to triangulate the epicenter of an earthquake. This program leads students step by step through the entire process of measuring the epicenter and calculating the magnitude of an earthquake. There is also an assessment tool associated with the program so that you can monitor how well your students did on the review quiz at the end of the activity.

Objectives
Can identify p and s waves on a seismogram.
Can calculate the distance from an earthquake epicenter to a seismographic station using p and s wave time difference.
Can triangulate the location of an earthquake epicenter.
Can determine the magnitude of an earthquake.
Can find the latitude and longitude of a place.

Vocabulary

fault
earthquake
epicenter
p wave
s wave
surface wave
magnitude
Richter scale
seismograph
seismogram
latitude
longitude

Attachment Size
sub_earthquake_prints.doc 49 KB
earthquake_prints_handout.doc 187 KB

Quake Prints - Logistics

Time
45-50 minutes

Grouping

Individual or in pairs depending on the number of computers you have.

Materials

  • Computers with internet access
  • Copy of the Earthquake Fingerprints handout for each student

Setting
Computer lab

Quake Prints - Background

Teacher Background
P and S waves: Image courtesy of USGS.P and S waves: Image courtesy of USGS.An earthquake has struck somewhere in California! Can you figure out where? If you learn to read a seismogram you can!

First some earthquake basics… (The following background information is provided in greater detail on the student handout.) There are faults (cracks in the Earth’s surface) that can suddenly move as pressure from the movement of the Earth’s crust builds up. This sudden movement is an earthquake.

An earthquake will generate different types of waves that travel through the earth and along its surface. Several different types of earthquake waves are triggered with every earthquake. Each wave makes particles in the soil move in different ways and travels at different speeds. For our purposes, we will focus on p waves and s waves.

P waves (primary waves) are side-to side compression waves and travel quickly through the Earth. S waves (secondary waves) are up-and-down waves and are typically more destructive. In an earthquake, s waves travel more slowly than p waves. Thus, even though p and s waves start at the same time from the epicenter of a quake, the farther they travel, the greater the delay between the p and s waves.

Seismogram: Image created by Crickett.Seismogram: Image created by Crickett.Earthquakes are recorded on instruments called seismographs which make recordings called seismograms. The x axis represents time while the y axis represents amplitude. The time axis can show the lag between when the p and s waves arrive and can thus be used to calculate the distance between the epicenter and the location of the seismograph. The amplitude axis reflects the strength of the shaking and can be used to calculate the magnitude of the earthquake.

The Virtual Courseware program takes students step by step through these calculations. In the “Travel Time” activity, students learn the relationship between p and s wave lag time and the distance from the epicenter. In the “Epicenter and Magnitude” activity, students use seismogram recordings to determine the epicenter and magnitude of an unknown earthquake.

Student Prerequisites
It is recommended that students are familiar with seismographs, seismograms, the difference between p and s waves, and reading latitude and longitude from a map before using the Virtual Courseware software. The student handout has a quick summary of this information, but 5 minutes to illustrate p and s waves with a slinky and to show students a seismogram before letting a sub take over would be helpful.

The program does provide a tutorial section that will show students a seismogram being generated and the propagation fronts of a p and s wave as they travel outward from an earthquake epicenter (the “SP Lag Time” tutorial). There is a second tutorial describing how to read latitude and longitude information (the “Latitude/Longitude” tutorial). If you don’t have time to preteach these concepts, then the tutorials can serve as a prelude to the 2 activities.

Quake Prints - Getting Ready

Getting Ready

  1. Reserve the computer lab.
  2. Register your class on the Virtual Courseware site in order for the results of your students’ review quiz to be saved.
    • On the main page, click the “Assessment” button under “For Instructors”.
    • Read the information under the “Information” button then register your class using the “Register” button.
    • Remember the class code and your password since these are required for you to retrieve your class results later using the “Class Results” button.
  3. Adapt the Earthquake Fingerprints handout so that the proper class code is entered on the second page near the bottom.
  4. Make copies of the Earthquake Fingerprints handout.

Quake Prints - Lesson Plan

Lesson Plan

  1. Give students the student handout and allow them read the first page. Be prepared to answer questions, especially with unknown vocabulary.
  2. Direct students to the Virtual Courseware - Earthquakes website (http://www.sciencecourseware.org/eec/Earthquake/).
  3. Optional: have students complete the tutorials before proceeding to the 2 main activities. This will take 10-20 minutes extra.
  4. Give students 40-45 minutes to work through the 2 activities and complete the quiz.
  5. When students are finished, the teacher can check each person’s certificate of completion.

Quake Prints - Assessment

Going Further

  1. Go on a field trip to the Lawrence Hall of Science and let their excellent educators teach your students all about using seismographs. Afterwards, let students explore the interactive exhibits in the Forces the Shape the Bay exhibition.
  2. Try any one of the activities in the Earthquake! curriculum set, created by the Center for Science Education at the University of California, Berkeley. There are lesson plans for building your own seismograph, reading seismograms, locating epicenters, and using seismic clues to understand the interior of the Earth.
  3. For a kinesthetic version of this activity, try Whose Fault is It? by Eric Muller of the Exploratorium Teachers’ Institute (download Whose Fault is It? from Eric’s website under Earth Science activities). Students link hands and transmit p and s waves through their bodies and use the timing delay to calculate the epicenter of the earthquake.
  4. Listen to an earthquake! USGS has converted seismograms to sound files. Students can use them to reinforce seismology concepts such as how distance and magnitude affect a seismogram.

Quake Prints - Sources

Sources
For information about earthquakes and seismology, see:

  • The Science of Earthquakes, an article by Lisa Wald on the USGS website.
  • G. H. Girty of San Diego State University has a comprehensive Flash based Geology 101 course including a good section Earthquakes. It is written for a college audience and includes practice exams which can easily be adapted for middle and high school students.
  • The Tech Museum of Innovation has an online exhibit on the science of earthquakes.

For an extensive list of earthquake teacher resources, check out the USGS Seismic  Waves page.

Standards
Grade 6
Plate Tectonics and Earth's Structure
1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.
g. Students know how to determine the epicenter of an earthquake and know that the effects of an earthquake on any region vary, depending on the size of the earthquake, the distance of the region from the epicenter, the local geology, and the type of construction in the region.

Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
c. Construct appropriate graphs from data and develop qualitative statements about the relationships between variables.

Field Trip - Lawrence Hall of Science

Summary
The Lawrence Hall of Science in the hills above UC Berkeley offers fantastic hands-on workshops and exhibits related to earthquakes and plate tectonics. The middle school program, “Earthquakes: Whose Fault Is It?” provides an excellent introduction to seismology. The program begins with a large puzzle of the Earth’s tectonic plates to introduce the idea of plate tectonics and begin a discussion of the location and movement of the tectonic plates. Students then investigate earthquakes and learn to read real and simulated seismograms. Finally, students use seismic recordings to locate the epicenter of an earthquake. Afterward the workshop, the permanent outdoor exhibit, “Forces that Shape the Bay” provides a free-form venue to explore plate tectonics through hands-on exhibits. The other exhibits and planetarium are also worthwhile.

Objectives
Can understand that the Earth’s crust is divided into large tectonic plates that are in constant motion relative to one another.
Can read a seismogram.
Can differentiate between p and s waves.
Can use the p and s wave arrival time difference to triangulate the epicenter of an earthquake.

Vocabulary
Tectonic plate
Seismograph
Seismogram
P wave
S wave
Epicenter

Time
50 minute Earthquakes: Whose Fault Is It? workshop
30 minutes to explore Forces that Shape the Bay exhibits
optional additional time to explore other exhibits and/or the planetarium

Attachment Size
lhs_trip.doc 44.5 KB

Lawrence Hall - Lesson and Planning

Teacher Background
When an earthquake strikes, several seismic waves radiate outward from the origin of the earthquake. These seismic waves may be thought of as ripples through the Earth’s crust that are similar to the ripples in a pond after a pebble has been tossed into the water. The origin of the earthquake is known as the focus or hypocenter of the earthquake. The epicenter is the point on the Earth’s surface directly above the hypocenter.

There are 2 major types of waves that travel through Earth. The first is the P wave, the primary or pressure wave. These are lateral compression waves. I think of these as a closely packed line of people waiting for tickets. One person bumps the person next to them who bumps the person next to them and so on through the line. The people represent molecules within the Earth that bump their neighbors as the p wave passes by. The second type of seismic wave is called the S wave, the shear or secondary wave. These travel as a transverse wave. I think of like a human wave at the ball park where one person standing up causes the person next to the to stand up and so on around the park.

P waves travel much faster than S waves, thus, the further you are from the earthquake epicenter, the greater the lag between the two waves. A seismogram is a record of these waves, captured digitally or on paper. The precise arrival time of the P wave and S wave is captured on the seismogram. Using several seismic monitoring stations, one may triangulate the location of any earthquake.

The teachers at the Lawrence Hall of Science are very skilled at leading these programs and quickly cover a lot of ground while maintaining the students’ interest and understanding. They are able to lead students through the plate tectonic causes of earthquakes, then how to read seismograms, then how to find the epicenter of an earthquake.

Planning Guide
To enroll in a program, there is a minimum enrollment of 16 and a maximum of 32 students. It costs $9.50 per student and includes access to the other exhibits, including Forces that Shape the Bay. The workshops occur at set times throughout the day: 10:00 a.m., 11:10 a.m., 12:30 p.m., or 1:30 p.m. Reservations may be made by calling: (510) 642-5134 or you may reserve online.

Lawrence Hall - Going Further

Going Further
There are a large number of ways to reinforce these same concepts back in your classroom.

  • Use the Virtual Earthquake software in the Earthquake Fingerprints lesson.
  • Whose Fault is it Anyway? is a great kinesthetic way to model epicenter finding developed by Eric Muller from the Exploratorium Teachers’ Institute. Students hold hands and propagate a p and s wave through a human chain. The difference in arrival times can be used to figure out who started the earthquake.
  • Finally, the Center for Science Education at the University of California Space Sciences Laboratory has a fantastic compilation of hands-on inquiry activity for the classroom on earthquakes. In addition to the standard stuff on reading seismograms for location and magnitude information, this series of lessons covers everything from using earthquake data to infer things about

Lawrence Hall - Standards

Standards
Grade 6
Plate Tectonics and Earth's Structure

1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
a. Students know evidence of plate tectonics is derived from the fit of the continents; the location of earthquakes, volcanoes, and midocean ridges; and the distribution of fossils, rock types, and ancient climatic zones.
c. Students know lithospheric plates the size of continents and oceans move at rates of centimeters per year in response to movements in the mantle.
d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.
e. Students know major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from plate motions.
f. Students know how to explain major features of California geology (including mountains, faults, volcanoes) in terms of plate tectonics.
g. Students know how to determine the epicenter of an earthquake and know that the effects of an earthquake on any region vary, depending on the size of the earthquake, the distance of the region from the epicenter, the local geology, and the type of construction in the region.

Shaping Earth's Surface
2. Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment. As a basis for understanding this concept:
d. Students know earthquakes, volcanic eruptions, landslides, and floods change human and wildlife habitats.

Heat (Thermal Energy) (Physical Sciences)
3. Heat moves in a predictable flow from warmer objects to cooler objects until all the objects are at the same temperature. As a basis for understanding this concept:
a. Students know energy can be carried from one place to another by heat flow or by waves, including water, light and sound waves, or by moving objects.

Field Trip - Marin Headlands

Marin Headlands: photograph of Marin Headlands from the Golden Gate Bridge by Christopher BelandMarin Headlands: photograph of Marin Headlands from the Golden Gate Bridge by Christopher BelandSummary
The Marin Headlands contain the geologic record of a great deal of plate tectonic action that can be used to piece together the history of the formation of California. Briefly, around 180 million year ago, the North American plate collided with a now subducted plate called the Farallon plate. As the Farallon plate dove under the North American plate, bits and pieces of the Farallon plate were scraped off. These bits and pieces can be found in the Marin Headlands in several distinctive rock formations: pillow basalts (at the Point Bonita Lighthouse), chert (near Rodeo Lagoon), and sandstone (at Rodeo Beach). By closely observing these rocks and figuring out how they formed, an understanding of how California itself was formed may be inferred.

Note #1: If you are intimidated by the trip as described here and prefer to have park rangers lead your field trip and geology investigations, consider participating in “Rocks on the Move”. This free program provides teacher training, pre- and post-visit curriculum, as well as a very knowledgeable ranger to lead the field trip portion of the visit.

Note #2: The geologic investigations undertaken in this field trip require students to have a good understanding of the rock cycle and the geologic time scale (see Geology Box) as well as exposure to the theory of plate tectonics. It is designed as a culminating field trip to tie lots of ideas together into a cohesive theory.

Objectives
Can make observations about the types of rock in the Marin Headlands.
Can model convergent, divergent and transform plate boundaries.
Can understand the conditions under which different types of rock form.
Can use evidence from rocks to piece together a theory of how California formed.
Can model the formation of California using sand castles.

Vocabulary
Mid-ocean ridge
Tectonic plate
Seafloor spreading
Convergent boundary
Divergent boundary
Transform boundary
Subduction
Island arc
Farallon plate
North American plate
Pacific plate
Sedimentary rock
Metamorphic rock
Igneous rock
Pillow basalt
Chert
Sandstone
Law of Original Horizontality
Law of Superposition
Law of Lateral Continuity

Attachment Size
headlands_trip.doc 63 KB
ca_timeline.pdf 15.66 KB

Headlands - Logistics

Time
2 hours at Point Bonita Lighthouse
10 minutes travel to Rodeo Beach
2 hours at Rodeo Beach and Lagoon
travel time to and from Marin Headlands varies

45-50 minutes back in classroom the following day to discuss, review, and consolidate field observations

Grouping
Whole class - preferably no more than 32 students on the trip at a time. For some activities, student divide into groups of 3-4 for discussion.

Materials

  • Small, lunch-sized ice chest
  • Ice
  • 2-3 cups of water
  • Clear plastic cup
  • Magic Shell® or other quick-hardening chocolate topping for ice cream
  • Hand lenses to observe radiolaria fossils
  • 1 package Oreo Cookies® or Nutter Butters®
  • Raised relief or shaded relief map of California (available from Hubbard Scientific and American Educational Products, $35.75 (http://amep.com/detail_maps.asp?cid=2255)

Setting
Marin Headlands, part

Headlands - Background

Teacher Background
The Marin Headlands offers an exquisite opportunity for students to consolidate everything they have learned about geology and plate tectonics. Students (with a lot of guidance and help) find and piece together evidence concerning the geologic history of California. Students observe 3 different rock types and learn about how each one formed. Then, they take these observations back to the classroom to consider several possible explanations for how these rock types all ended up in the same place.

Pillow Basalt

Pillow Basalts at Point Bonita: image courtesy of the US Geological SocietyPillow Basalts at Point Bonita: image courtesy of the US Geological Society Pillow Basalts forming at Loihi: newly formed pillow basalt at the understaer volcano, Loihi, in Hawaii, image courtesy of the US Geological SocietyPillow Basalts forming at Loihi: newly formed pillow basalt at the understaer volcano, Loihi, in Hawaii, image courtesy of the US Geological Society


The first rock formation students observe are the pillow basalts at the Point Bonita Lighthouse. The best observation point is past the tunnel, on the left side of the 2-man suspension bridge, before you cross over to the lighthouse itself. If you look down, there is a picture perfect outcrop of pillow basalt right near the water. Another place to observe pillow basalts is on the cliffs on the right side of the trail, before reaching the tunnel. These pillows have been cut in half and may be seen exposed on the cliff as oval-shaped pockets of basalt.

This type of basalt forms when magma spills into cold ocean water. The outer layer of basalt rapidly hardens when it contacts the ice cold water, forming a round, pillow shaped shell. As more magma pushes from behind, part of the shell bursts and more magma rushes out. This pattern of magma release leads to a formation similar to pillow stacked one on top of another, or similar to the pattern made (in miniature) when Magic Shell® chocolate topping is dropped into ice water.

Two places one might expect to find pillow basalts forming is 1) at a volcanic island arc near a convergent plate boundary or 2) at a mid-ocean ridge where magma from the mantle pours out from between the gap between two diverging plates. While the pillow basalt found elsewhere in the Marin Headlands is consistent with a mid-ocean ridge origin, based on chemical analysis of the titanium and iron content, these pillow basalts at Point Bonita seem more consistent with a volcanic island origin.

Sandstone
Rodeo Beach and sandstones: image courtesy of nickoneill (http://flickr.com/photos/nickoneill/)Rodeo Beach and sandstones: image courtesy of nickoneill (http://flickr.com/photos/nickoneill/)A short drive from the lighthouse takes you to Rodeo Beach. You can park at the north end of the beach by the restrooms.

The second rock formation students observe are the sandstone cliffs at the northern end of Rodeo Beach, near the parking area. These sandstone cliffs are typical of sandstones formed from the sedimentary remains of underwater landslides at the edge of a continent, generally near a subduction zone. One can tell that these sandstones were laid down in large, tumultuous landslides because they closely resemble a hugely magnified version of a soil separation test (see Soil Analysis lesson) – where sediments of various grain sizes are shaken in water and the large pebbles settle near the bottom and the smallest particles settle near the top. The sandstone formations similarly show a pattern of layered beds several meters thick. In each bed, large pebbles are found near the bottom and tiny clay particles may be found at the top, suggesting that the entire layer collapsed off the edge of the continent underwater, and sorted by particle size before being compacted and cemented together into a sandstone.

Chert
Ribbon Chert in the Marin Headlands: image courtesy of the US Geological SocietyRibbon Chert in the Marin Headlands: image courtesy of the US Geological SocietyTake the students south down the beach and hike around Rodeo Lagoon, a beautiful 1 mile walk. About 3/4 of the way around the lagoon, there is a tall, exposed chert cliff face on the opposite side of the road, with a nice open area at the base for students to gather and observe the rocks.

Chert is composed of several centimeter thick layers of radiolaria fossils. Radiolaria are tiny oceanic creatures whose shells drift down to the ocean floor when they die. Over many millions of years, their shells pile up on each other and form layers, which, as specified in the law of original horizontality, were originally laid down flat.

How then did the layers get so torturously folded? To illustrate the process, take an Oreo Cookie or Nutter Butter and carefully twist off the top cookie, leaving the filling in a nice layer on top of the bottom cookie. The top cookie represents a continental plate. The filling represents the chert, laid down in nice flat layers. The bottom cookie represents an oceanic plate, which will subduct under the continental plate. Hold the continental plate cookie still and gradually allow the oceanic plate cookie to dive below the edge, scraping the chert filling off of the oceanic plate cookie as it goes. You should get a wrinkled, folded pile of filling on the edge of the continental plate cookie. This same process explains how the originally flat layers of chert became so wrinkled and folded – as the oceanic crust subducted, the chert was scraped off the surface and piled up on the continental crust.

Putting it all together
Knowing the stories of these three rock types, it becomes clear how this piece of California formed. Around 200 million years ago, Pangaea began to break up. The North American Plate moved westward, away from what is now Europe and Africa. At that time, California did not exist. The edge of the North American continent was in Nevada. As the North American Plate traveled west, a now almost entirely subducted plate called the Farallon Plate dove under the edge of the North American Plate. This subduction began around 160 million years ago. This subduction zone resulted in oceanic rock being scraped off the Farallon plate and piling up against the edge of the North American continent. Gradually, California grew as the North American Plate pulled off chunks of ocean floor – pillow basalts, cherts, and entire island chains the size of Japan – like a continent sized bulldozer.

At the same time, magma rose up from beneath the descending plates, causing the formation of large volcanoes on the North American Plate, such as Mount Lassen and Mount Shasta. Some of the magma never broke through the crust as a volcano. Instead, the balloons of magma cooled gradually beneath the surface, formed huge granite mountains, and pushed up the Earth’s crust. These granite mountains form the bulk of the Sierra Nevada.

By 100 million years ago, these newly formed mountains had begun to erode heavily. Vast amounts of sediment washed down off the mountains and extended the edge of the continent further west, creating the Sacramento Valley. The bulldozer action of the North American Plate continued. The sandstone formations (like those on Rodeo Beach) provide evidence that the Marin Headlands is the edge of the continental plate. The pillow basalts (like those at the Point Bonita Lighthouse originally created near mid-ocean ridges and far away volcanic islands) and chert (like those near Rodeo Lagoon originally laid down in the ocean in nice flat layers) were unceremoniously scraped off the Farallon Plate. These pillow basalts and chert are the last remaining remnants of the Farallon Plate. By 28 million years ago, the Farallon Plate had been entirely consumed.

Student Prerequisites
Before undertaking this field trip and investigation, students should have a thorough understanding of the rock cycle (see Rock Cycle lesson), basic geology (see the History of Rock lesson), stratigraphy (see Layers Upon Layers lesson), geologic time (see Geologic Timelines lesson), soil separation tests (see Soil Analysis lesson), seafloor spreading (see Seafloor Spreading lesson), and plate tectonics (see Evidence for Plate Tectonics lesson).

Headlands - Getting Ready

Getting Ready

  1. The Point Bonita Lighthouse is only open on weekends and Mondays from 12:30 to 3:30. To have a docent or ranger open the lighthouse tunnel for you on other days and times, contact the National Park Service at (415) 561-4754.
  2. Arrange transportation to the Marin Headlands and around the park.
  3. Gather materials:
  • small ice chest, ice, water, cup and Magic Shell for the pillow basalt demonstration
  • hand lenses and cookies for chert observations
  • map of California for putting it all together

Headlands - Lesson Plan

Lesson Plan

  1. Before going on this trip, review any of the science concepts that students should have fresh in their minds: rock cycle, basic geology, stratigraphy, geologic time, seafloor spreading, and plate tectonics
  2. Go to the Point Bonita Lighthouse in the Marin Headlands.
  3. Investigate the pillow basalts:
    • Begin by asking students to draw or photograph the pillow basalts.
    • Model the formation of pillow basalt with ice water and Magic Shell. Fill a cup with ice water and then pour Magic Shell into the water – the cold water makes the outside of the chocolate syrup harden and the chocolate soon piles up in pillow shaped piles.
    • Discuss the model with the students, pointing out how the syrup represents magma welling up on the ocean floor.
    • Ask students where magma might well up from the ocean floor: volcanic islands and mid-ocean ridges.
  4. Travel to Rodeo Beach.
  5. Investigate the sandstones:
    • Ask students to draw or photograph the sandstones. Point out the borders between each large layered sandstone bed.
    • At the water’s edge, observe how sand particles act in the water. Draw connections to the soil separation test and the tiny particles remain suspended in water but the larger particles rapidly settle to the bottom.
    • Point out the sorting of the sediments in each bed.
    • Discuss how much sand would need to be dumped at one time to create each bed.
    • Ask students what might cause this much sediment to be dumped at one time: under-water landslides.
    • Point out how large landslides are known to occur at the edge of a continent, particularly near subduction zones.
  6. Lead students on a counter-clockwise walk around Rodeo Lagoon.
  7. Stop at the chert outcrop and investigate the chert:
    • Ask students to draw or photograph the chert. Pass out hand lenses and encourage students to look for fossils.
    • Review the law of original horizontality. Ask students how these layers must have been laid down originally. How did the bodies of these fossils originally form layers? (By millions of years of accumulation on the ocean floor.)
    • Ask students for initial hypotheses about how these layers could have become so folded.
    • Pass out cookies and model the subduction of an oceanic plate with cookies. Carefully remove the top cookie, leaving the filling on top of the lower cookie. Hold the top cookies still while gradually moving the lower cookie so that it subducts unter the top cookie, scraping off the filling as it goes.
    • Discuss the model, pointing out what the cookies and filling each represent. Observe the similarities between the now wrinkled filling and the folded layers of chert.
    • Collectively piece together the story of how this chert was originally laid down and how it became wrinkled.
  8. Return to the parking lot and go back to school (or play on the beach a little first).
  9. At school, review the stories of the 3 rocks that were investigated. Discuss how each type of rock must have formed, specifically focusing on where it must have formed.
  10. Spend at least half an hour piecing together the story of how all 3 types of rock, sandstone, chert and pillow basalt, came to all be found in one place. Once the story is filled out, diagram it on the board.
  11. Use the relief map of California to show the 3 major geologic zones in California – the Sierra Nevadas, the Central Valley, and the Coast Range mountains.
  12. Tell the story of how each of the 3 zones formed. Create a timeline to show students what was happening at different periods.

Headlands - Sources and Standards

Sources
All the models - chocolate pillow basalt and cookie chert – were introduced to me by Eric Muller of the Exploratorium Teachers’ Institute. For detailed information about the chocolate pillow basalt demonstration, see his write up “Chocolate Lava” on his website.

The best overview of the geology of the San Francisco Headlands region is available in the book: The Geology and Natural History of the San Francisco Bay Area: A Field-Trip Guidebook, edited by Philip W. Stoffer and Leslie C. Gordon, published by USGS. The information you want is found in the third field trip, “Geology of the Golden Gate Headlands”, stop #2, 3, and 4. The entire guide with other excellent field trips throughout the Bay Area may be downloaded from. The USGS provides an online photographic tour of the Golden Gate National Recreation Area, including a great geologic map of the Marin Headlands.

Two excellent books describing the geologic history of California are:

  • California Geology, by Deborah Harden, 2003, Prentice Hal
  • Assembling California, by John McPhee, 1994, Farrar Straus Giroux

Some good websites for additional information about the history of California include:

  • The National Parks Service website has a great image of North America showing the various geological regions with a brief description of their formation.
  • This USGS bulletin carefully describes many important characteristics of the geology of the Bay Area.

Standards
Grade 6
Plate Tectonics and Earth's Structure
Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:
a    Students know evidence of plate tectonics is derived from the fit of the continents; the location of earthquakes, volcanoes, and midocean ridges; and the distribution of fossils, rock types, and ancient climatic zones.
e     Students know major geologic events, such as earthquakes, volcanic eruptions, and mountain building, result from plate motions.
f     Students know how to explain major features of California geology (including mountains, faults, volcanoes) in terms of plate tectonics.

Shaping Earth's Surface
Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment. As a basis for understanding this concept:
a     Students know water running downhill is the dominant process in shaping the landscape, including California's landscape.
b     Students know rivers and streams are dynamic systems that erode, transport sediment, change course, and flood their banks in natural and recurring patterns.
 
Investigation and Experimentation
Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
e     Recognize whether evidence is consistent with a proposed explanation.
f     Read a topographic map and a geologic map for evidence provided on the maps and construct and interpret a simple scale map.
g     Interpret events by sequence and time from natural phenomena (e.g., the relative ages of rocks and intrusions).

Grade 7
Earth and Life History (Earth Sciences)
Evidence from rocks allows us to understand the evolution of life on Earth. As a basis for understanding this concept:
a     Students know Earth processes today are similar to those that occurred in the past and slow geologic processes have large cumulative effects over long periods of time.
c     Students know that the rock cycle includes the formation of new sediment and rocks and that rocks are often found in layers, with the oldest generally on the bottom.