How much is a million? How big is a billion? Getting a handle on the immensity of geologic time
Danita Brandt, Elizabeth Conover, and Kristen Johnson
, Michigan State University
Summary
We constructed a geologic timeline along a 5K road-race route across the MSU campus at a scale of 1 meter = 1 million years, using signage to mark important events in the history of life. In addition to over 1500 race participants, numerous casual observers were exposed to the timeline. This project works well in the classroom at a scale of 1 mm = 1 million years, and as a manageable one-day outdoor sidewalk chalk activity at a scale of 1" = 1 million years. Timelines drawn to scale lead the observer to the inescapable conclusions that "simple" life appeared early in Earth history; that it took the bulk of Earth history to achieve the next, multi-cellular stage of development; and that once the metazoan threshold was crossed, subsequent biological diversification-and the resulting fossil record-followed in rapid succession.
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Context
Audience:
general public
Skills and concepts that students must have mastered:
no prior skills necessary; concepts: the Earth has changed through time, we have ways to calibrate that record of change, and we can put events in their proper chronologic order
How the activity is situated in the course:
may be used as stand alone or as follow-on to discussion of the development of the geologic time scale
Goals
Content/concepts goals for this activity:
Immensity of geologic time; the proper chronologic perspective of the eons, eras, and periods of the geologic time scale
Geologic skills:
becoming familiar with the geologic time scale
Higher order thinking skills goals for this activity:
interpreting a two-dimensional representation (charts of geologic time scale) in its proper 4th dimensional aspect (time)
Other skills goals for this activity:
measurement, scaling, unit conversion
Description of the activity/assignment
We constructed a geologic timeline along a 5K road-race route across the MSU campus at a scale of 1 meter = 1 million years, using signage to mark important eventsin the history of life. In addition to over 1500 race participants, numerous casual observers were exposed to the timeline. This project works well in the classroom at a scale of 1 mm = 1 million years, and as a manageable one-day outdoor sidewalk chalk activity at a scale of 1" = 1 million years. Timelines drawn to scale lead the observer to the inescapable conclusions that "simple" life appeared early in Earth history; that it took the bulk of Earth history to achieve the next, multi-cellular stage of development; and that once the metazoan threshold was crossed, subsequent biological diversification-and the resulting fossil record-followed in rapid succession.
Evaluation
To know: whether students develop a more accurate view of events in Earth's deep history relative to more recent events for which we have a more abundant record pre- and post-activity quizzes
Logistics
no special tools required
Poster Presentation
How much is a million? How big is a billion? Getting a handle on the immensity of geologic time (PowerPoint 498kB Feb15 06)
