A LONG, LONG time ago: geologic timescales

Elizabeth Johnson
,
James Madison University
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Summary

Students compare their pre-conceived impressions of events on the geologic time with the actual positions of these events on a 45.5' geologic timescale.

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Context

Audience

This activity, or a similar version, is used in many introductory, general education courses at JMU including Physical Geology and Earth Systems and Climate.

Skills and concepts that students must have mastered

None. Understanding the concept of scale helps, but it is not necessary.

How the activity is situated in the course

A stand-alone exercise as part of a brief (1-2 lecture) discussion of geologic time.

Goals

Content/concepts goals for this activity

Students learn about the relative and absolute timing of a set of geologic events, and contrast geologic timescales and human timescales.

Higher order thinking skills goals for this activity

Developing scale models

Other skills goals for this activity

Working in groups

Description of the activity/assignment

Each student randomly picks a card with a geologic event (written description and an image) on it. A timeline has 11 events, not including the formation of the Earth and today. Students attach their event where they think it should go on a 45.5' timeline (in the hallway) made out of paper adding tape and mark the location on the timeline. They return to the classroom and receive a list of age dates for each event. Each group figures out the scale (1 foot = 100 million years) and then moves their events to the correct locations. Students are asked how the position of the events changed, and answer other questions that reinforce the difference between human timescales and geologic timescales. The powerpoint file below contains a template for making geologic event labels for the index cards. Instructors can tailor the geologic event list to fit their course.

Determining whether students have met the goals

I check each timeline after the "correction" phase to make sure all events are placed correctly. We go over the answers to the thought questions in class after they are finished with the assignment. Questions from this exercise are fair game as test questions.

More information about assessment tools and techniques.

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