6. Geologic Timelines

For students, a few days can feel like a very long time. Thus, my students have a hard time conceptualizing the difference between 1 thousand, 1 million and 1 billion years. In this activity, students develop a sense of just how long the geologic time scale really is by creating a to-scale geologic timeline. This lesson begins with students guessing how long ago different events happened – when the Earth was formed, when life began, when dinosaurs roamed, and when humans first appeared. Then students redraw the periods and eras of the Phanerozoic Eon to scale using adding machine tape (1 million years = 1 millimeter). Then a teacher created scroll containing the other eons: Proterozoic, Archean and Hadean is unrolled to give students a visual sense of just how long Earth history really is. Finally, there are some analogies for students to contemplate, such as when different events would have occurred if Earth history were condensed into a calendar year or into a cross country trip.

Can read information from a Geologic Time Scale
Recognize that many changes in biodiversity have occurred since life evolved on Earth
Can describe the major forms of life in each eon and in each era of the Phanerozoic Eon
Develop a sense of the vastness of geologic time

Geologic time
Geologic time scale
Phanerozoic Eon
Proterozoic Eon
Archean Eon
Hadean Eon
Paleozoic Era
Mesozoic Era
Cenozoic Era

geologic_time_handout.doc49 KB
6geologic_timelines_v2.doc68.5 KB