Geologic Puzzles: Morrison Formation
This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.
Outcrop images (faulted strata, interbedded shale and limestone beds that have been tilted, beach rocks of different lithologies) can be used to bring the field into the geoscience classroom, giving students practice in doing what geoscientists do when they are in the field. These particular images are examples of interesting geologic puzzles.
These images give students opportunities to practice interpreting the geologic history of an outcrop or other feature by having them
- make observations
- present interpretations based on their observations and on their prior knowledge
- pose questions for further information
Context for Use
These images can be used in both small and large classes in various think-pair-share formats, with times ranging from five to twenty minutes per image. These images have been used in historical geology courses and could be used in other geoscience courses.
Description and Teaching Materials
Fault with Morrison Formation on left side of image and Entrada Formation overlain by Morrison Formation on right side. Photo courtesy of Heather Macdonald
- Are these igneous, metamorphic, or sedimentary rocks?
- Are the layers continuous across the outcrop?
- Can you identify any unit that is present on both sides of the image?
- How can you explain this?
- What type of fault is shown in this image?
- If you could get closer to the outcrop, what you look for?
Teaching Notes and Tips
One approach for using these images would be to have students discuss the image with their neighbor, asking them what do you see and what does it mean. To emphasize observations and to provide more structure, you could ask the students to
- make a simple sketch and/or a list of their observations
- make an initial interpretation
- share their ideas with another student
- list questions they would want answered to be able to make a better interpretation or to evaluate alternate interpretations
In either case, after a few minutes, call for responses from students. You might do this using a using a think-pair-share format. Be prepared for a range of responses including ones you might not anticipate. Student answers provide useful insight into their observational skills and thought processes.
The potential questions given below with each image are examples of questions to use as follow-up questions after students give their initial responses or could be a series of directed questions if you don't use a think-pair-share structure.
This activity includes informal assessment of the class. You could also collect the sketches and or lists of observations and interpretation(s).
References and Resources
This kind of activity is described in Reynolds and Peacock (1988) .
Sources for images:
- The American Geological Institute maintains a growing Image Bank (more info) , divided by category.
- Earth Science Picture of the Day (more info) has a searchable archive of photos.
- Martin Miller, a geology professor at the University of Oregon, has posted an online slide collection (more info)
- Lou Maher, a geology professor at the University of Wisconsin, has collected aerial views in his Geology by Lightplane (more info) project