Expedition to the PreCambrian
Summary
A group exercise that investigates geological, atmospheric, hydrologic, and biological conditions during the Hadean, Archean, and Proterozoic. Students will plan a trip to a certain time period within the Precambrian, research critical environmental clues, and report their findings with a group presentation to the class.
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Context
Audience
Introductory historical geology course for non-majors (and majors)
Skills and concepts that students must have mastered
Overview of Hadean, Archean, and Proterozoic Earth in terms of key events and questions concerning tectonics, evolution of the atmosphere, and life.
How the activity is situated in the course
A group assignment that involves classwork (possibly a homework assignment), and a group report to the class.
Goals
Content/concepts goals for this activity
- Describe and capture a basic understanding of key events of the Precambrian (through lecture and reading).
- Research, analyze, and evaluate a segment of geologic time in the Precambrian that illustrates a particularly interesting event or situation.
- Report findings to the class as a number of individuals working within the group.
Higher order thinking skills goals for this activity
- Summarize and evaluate important Earth processes, situations, and events.
- Synthesize available and abstract evidence concerning Earth environments into concrete terms regarding human experience
Other skills goals for this activity
- Capture the advantages and dynamics of group work.
- Acquire/develop presentation skills.
Description of the activity/assignment
1. Instructor identifies an appropriate number of key dates in the Precambrian to investigate.
2. Students break into groups (method to be determined by instructor) and each group will be assigned a particular time in the Precambrian (one author likes to have groups draw assignments out of hat!).
3. Students investigate their time period using appropriate source materials (we suggest the class notes, textbook and perhaps supplementary materials identified in the form of popular articles (e.g., Scientific American, Smithsonian, National Geographic, etc.) or websites.
Questions
- Using your prior knowledge of your time period, what scientific equipment might you want to take with you?
- What will you experience on your time travels?
- Is there a place to land?
- What is the temperature?
- Can you breathe the atmosphere?
- Do you need a life support system?
- What is the atmosphere composed of?
- Is there any water? What is its phase? Can you drink it?
- Do you see any life, or evidence of its presence? How would you recognize the life?
- What life do you expect to observe or not observe, and why?
- What questions were you able to answer with your trip?
- What questions were you unable to answer?
- What aspects of the environment at this time most surprised or stuck you?
4. Group presentation
a) Create a very simple PowerPoint presentation (10 minutes) for the class.
b) Each group member must present part of the information.
Determining whether students have met the goals
1. Presentation and PowerPoint sides evaluated by instructor using rubric.
2. Groups submit question or questions as possible exam questions.
Teaching materials and tips
Activity description and grading rubric (Microsoft Word 34kB Feb20 08)
Other Materials
Supporting references/URLs
General
The Divisions of Precambrian Time
The Precambrian from Palaeos
Map of Precambrian rocks in North America from the USGS North American Tapestry of Time and Terrain
Map of Late Precambrian Supercontinent and Ice House World
by Encyclopedia Britannica (requires a free trial membership)
The Precambrian Eon by Earth Floor
Life
The Dawn of Animal Life Miller Museum Online Exhibit
Study Suggests Clay Paved the Way for Evolution of Complex Animals, by David Biello, Scientific American
First Life, Michael Russell, American Scientist, January-February 2006
The Origin of Animal Body Plans, by Douglas Erwin, James Valentine, David Jablonski, American Scientist, March-April 1997