Grand Canyon Exercise: Geological Time, History, and Sedimentary Environments

Introduction and Instructor's Notes

Dexter Perkins
Dept. of Geology
University of North Dakota

This exercise may be used for any non-profit educational purpose.

The Grand Canyon is a fascinating and captivation feature. So, it is a great teaching tool. This exercise is always a hit with students and gives them a chance to "do" science and make interpretations regarding sedimentary environements and the reconstruction of geological histories.

The exercise itself (the page that students go to) is at grandcan.htm (click here to get to page).

This exercise is appropriate for college level introductory geology. Perhaps also for some gifted high school classes. The key to it being a success is to impress on the students that science is not just regurgitating facts, but involves combining facts and other information to explain things. Sometimes I use this exercise in the middle of the semester - after students have gone through the usual chapters on sedimentary rocks and geological time, etc. Other times I use this very early in the course - after only a brief introduction to time and rocks. Either way it works, but I think they get more out of it if they do it before we discuss time and rocks in detail. Students are smart, and they can figure things out if given the right encouragement. And, if they figure out a history of the Grand Canyon, they have an appreciation for time and sedimentary environments that carries naturally into lectures, chapters, or other sources of information.

The project has two parts. First the students go through some photos and answer questions. The questions and the photo captions give them some valuable information that they will use in the second part of the exercise.

For the second part of the exercise they have to write a history of the Grand Canyon. I tell students there is no correct answer nor any correct way to tell the story. I encourage creativity. Because many students in my intro classes are not geology (and often not science majors), the papers are of many sorts. They are highly variable in quality and approach. Some take a very pure "scientific" approach. Others write more of a real story, and may use anthropomorphisms when discussing the rocks. Some are very hesitant to interpret and just repeat facts; others get into the project once they realize that I really don't care what they say - as long as it makes sense.

This is an excellent project to have students critique each others work. After they turn in the papers, make copies (without names) and hand them out to groups (3-5 students) and have them evaluate the papers and make a list of the things that make a paper strong or weak. Then have a plenary session and tally all the comments on the blackboard. The students will do your grading for you! I ask them to identify what they consider to be the best papers, tally the votes, and then give some sort of prize - perhaps a geology calendar - to the best student scientist.

Fabulous prizes for the best story!

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