Relative Dating on Earth and Mars
University of British Columbia
This activity has benefited from input from faculty educators beyond the author through a review and suggestion process.
This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Apr 29, 2008
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Students apply principles of relative dating to a cross-section, then to the surface of Mars.
I use this in an introductory-level course for non-science majors
, who are in the course to fulfill a general education requirement.
Skills and concepts that students must have mastered
Students should have read about principles of relative dating and the principle of uniformitarianism. The activity asks them to apply the principles, so it's OK if they haven't yet mastered them.
How the activity is situated in the course
This is a short (~10 minute) exercise in class that supports learning about how geologists decipher histories from rocks.
Content/concepts goals for this activity
Application of principles of relative dating. Extension activity combines relative and absolute dating.
Higher order thinking skills goals for this activity
Make logical inferences based on observations.
Other skills goals for this activity
Working in groups; explaining principles to other students.
Description of the activity/assignment
This activity asks students to interpret (1) a geologic cross-section, then (2) the surface of another planet (Mars) in order to construct a logical sequence of events that explain how it came to look the way it does. Students need to use principles of relative dating, such as superposition, cross-cutting relationships, inclusions, original horizontality, or original continuity. An extension activity adds a few absolute dates and a couple of fossils to the original cross section and asks students to bracket the possible range of ages for an undated feature of the cross-section.
Determining whether students have met the goals
On a quiz, I ask students questions about individual principles (e.g. which layer is youngest?). On an exam, I ask students to interpret a sequence of events for a different cross section than the one they saw in the activity. I survey students about the in-class activities and ask which they thought were particularly useful/not useful. This one is often mentioned as an activity students remember, usually in a positive light.
More information about assessment tools and techniques.
Download teaching materials and tips
Source for Mars image:
http://volcano.und.edu/vwdocs/planet_volcano/mars/Cones/uranius.html (Viking Orbiter image 516A23)