Field Trip - Caldecott Tunnel

To apply students’ understanding of the rock cycle and basic principles of stratigraphy, I brought my students to the Caldecott Tunnel to investigate the local geology and piece together the geologic history of their backyard. The east side of the tunnel has an easily accessed road cut that displays a gorgeous example of a contact between older sedimentary rock layers and a more recent volcanic layer. The whole thing has been folded and faulted by the actions of the Hayward Fault, and thus the layers are no longer horizontal but at a sharp diagonal. My students drew pictures of the northern cliff face on the Orinda side of the tunnel then each student was assigned a rock layer to study in detail. When we got back to the classroom, we reassembled the data on the whiteboard, and made theories about the sequence of events that would bring about the rock layers we observed in the cliff. Finally, students drew pictures of what the area must have looked like at different parts of the timeline. This field trip led gracefully into the next segment of the unit on geologic time.

Caldecott Tunnel - north roadcut
Photograph of the northern roadcut face at the Caldecott Tunnel from the field trip “Caldecott Tunnel between Oakland and Orinda” by Russell W. Graymer in "The Geology and Natural History of the San Francisco Bay Area: A Field-Trip Guidebook", edited by Philip W. Stoffer and Leslie C. Gordon.


4. My Time

This simple lesson gets students accustomed to reading a Geologic Time Scale and understanding the organization of the information contained in it by creating a Personal Time Scale using events from their own lives. Students list major life events then arrange them by relative time. Then, based on whatever organizational scheme makes the most sense to them, they divide their lives into eons. Each eon is divided into eras and each era into periods. Students can then view events in their own life with events in the history of Earth. In addition, they learn the difference between relative time (whether one event came before another) and absolute time (how many years ago something happened).

3. Layers Upon Layers

Grand Canyon

The study of rock layers, or stratigraphy, is a natural way to introduce students to the fundamental principles of geology and to lead into the idea of geologic time. In this lesson, students are introduced to Nicolas Steno’s 3 major laws of stratigraphy: the law of original horizontality, the law of superposition and the law of lateral continuity. Students also add their observations of sediment sorting from previous lessons (Soil Analysis, Erosion Patterns, and the Sediment Study Project) to generate a fourth “law” concerning depositional environment – the tiny grains in mudstone were most likely deposited in very still water like a lake or delta while large gravel in conglomerate was most likely deposited in fast moving rivers and streams. While this activity has students depositing sediments in clear plastic cups or Mason jars, it is recommended that the teacher simultaneously conduct the activity using a squeeze box like the one described by Eric Muller. In this way, when the student activity concludes, the teacher can take the activity further to show how layers can become folded and faulted by plate movements. This lesson is a natural extension of the Going Further activity from the Crayon Rock Cycle lesson where sediments are mixed with sodium silicate to create home-made sedimentary rocks.

1. Crayon Rock Cycle

What's the big deal about rocks? They don' move, aren't flashy, and seem pretty useless to the untrained eye. To discover the beauty of rocks, one must look closer and learn how to read them. Geologists are rock detectives, discovering clues to the ancient past. If you know how to read them, rocks can tell an observant scientist about what a place looked like millions and even billions of years ago. This activity introduces the 3 main types of rocks and the processes that form them. Wax crayons are eroded into sediment, compacted into sedimentary rock, partially melted and pressed into metamorphic rock, and finally melted and cooled into igneous rock. This understanding is the basis of the rock cycle. In the Going Further section, there is a recipe for making your own sandstone, siltstone and conglomerate using sediments and a sodium silicate solution.

Can describe the 3 major types of rock (sedimentary, metamorphic, and igneous) and discuss the relationships between them
Can diagram the rock cycle
Given one of the three major types of rock, can describe the geologic processes that formed it

Geology Box

Mt Diablo caves
This box is all about the geology of the San Francisco Bay Area and Earth history. Students will learn about the rock cycle and the types of rocks that form under different conditions. Using this knowledge, students will investigate the rock layers exposed alongside the Caldecott Tunnel (Highway 24). Their explorations will reveal the geologic history of the San Francisco Bay area as it transitioned from ocean, to riverbed, to flood plain, to volcano, and then back to ocean again. In addition, students will research and create a timeline of life on the planet investigating the various life forms throughout the history of our planet and putting our own miniscule existence as human beings into the context of the enormity of Earth history.

Project - Terraqua Column Experiment

Once students have some experience working with a basic terraqua column (see the Terraqua Columns Lesson), they have an opportunity to design and conduct their own investigations with their mini-ecosystems. There are hundreds of variables students can manipulate with a minimum of materials – temperature, light, pollution, type of water, type of soil, etc. As a class, students brainstorm variables that might affect the plants, soil, and/or water in a terraqua column. In teams, students propose a project, and once approved, set about testing their ideas and observing the effects of their manipulations on their mini-ecosystem. If your school participates in a local science fair, this is a fantastic activity to introduce students to experimental design, variables, and control groups.

7. Erosion Patterns

This lesson is an extension of the GEMS guide: “River Cutters” by the Lawrence Hall of Science (see note below). In the GEMS curriculum, students are introduced to erosion by modeling the formation of rivers in tubs of diatomaceous earth, a silt-like substance into which meandering river channels and deltas form. This lesson builds off of the River Cutters activities by using a combination of sediment types in the models. They observe how gravel and large particles of sand remain in place whereas silt is washed downstream in fast flowing river channels. In contrast, where the water velocity slows as it reaches the newly forming bay, a beautiful silt-covered delta forms. These observations lead students to the conclusion that fast moving water picks up the smaller sediment particles and eventually deposits them in places where the water slows. Students can then take this theory to test it out in real world conditions at a local creek in the Sediment Study Project, observing sediments and water velocity at different sites along a creek’s length. The concept of how sediments are deposited becomes a core feature of subsequent geology lessons and investigations in which the environmental conditions surrounding the formation of large particled conglomerates may be differentiated from small particled shales and siltstones.

GEMS River Cutters

Special Note: This lesson plan is written with the assumption that students have some experience using the river models in the GEMS guide “River Cutters”, written by Cary Sneider and Katharine Barrett and produced by the Lawrence Hall of Science. In this guide, students make observations of rivers carved in just silt (diatomaceous earth), sequencing events in time, noticing patterns, recording information, and acquiring the terminology necessary to describe common erosion patterns. My students completed the first 5 sessions of River Cutters although completing the first 3 lessons is sufficient. So as not to infringe upon the copyright of the GEMS unit, only the extension activity is described here.

Project - Sediment Study

In this culminating project, students go out into the field and test their theories about erosion and sedimentation at a local creek. How are sediments distributed along the creek? Does it vary by location (the source, mid-stream, and the mouth)? Does it vary by the velocity of the current? Different classes can collect information for the different study areas. At a study site, they will draw maps, measure the velocity of the current, and collect sediment samples from the creek bed. These samples are analysed back in the classroom for the percent of different sediments they contain. Finally, students stand back and examine their data to try to make sense of the sediments they find. If it is not possible to bring students to a creek, there are many ways to bring the data to them. Collect the sediment samples yourself with photos and water velocity information OR use the Suspended Sediment Database to draw your conclusions. This USGS database provides stream flow and sediment information for over 1,500 rivers and creeks nationwide (see the Going Further section for more information on using the USGS’s database).

6. Topo Tour

Once students understand the basics of how to read and create a topographic map (see From Maps to Models lesson), students will study and label a topographic map of their local watershed. They will identify the creek closest to their school and mark the boundaries of their watershed. In the process, they practice recognizing hills, ridges, valleys, stream beds and other geographical features on a topographic map. Finally, students take their maps and walk a part of their watershed, matching their maps to their real world surroundings. If a walk through your neighborhood is not possible, the lesson can be conducted without the watershed walk. The watershed walk portion of this lesson may be combined with the Sediment Study Project.

5. From Maps to Models - Sources and Standards

Activity descriptions and ideas
I first learned how to make topo maps from Eric Muller of the Exploratorium’s Teacher Institute. I changed the method for making the topo map from the models but otherwise our activities are very similar. You can download his "To Topo Two" activity below or from his website with other stellar activities.