Coldwater Cave Fault Line

These two images show a space in Coldwater Cave.

Image One: Shows the layers of rocks in the cave that are of different colors. The colors are due to the oxidation of the rock by rising and falling flood waters.
Image Two: Shows the same area but includes a person standing with their hands at the same rock layer across the space. This shows how the layers have shifted due to the crust of the Earth moving.

Winneshiek County

Iowa Core Standard

HS-ESS1-5

Evaluate evidence of the past and current movements of continental and oceanic crust and the theory of plate tectonics to explain the ages of crustal rocks

Driving Question

Why are the rock layers shifted on each side of the space?

Probing Questions

What do you notice about the layers or rocks?
What is different from one side of the space to the other?
What caused the rock layers to shift?

Classroom Suggestions

Students could:

Observe the images and try and describe the rock layers
Construct a way to show how the space formed and the layers shifted
Try to compare this to other phenomenon in their lives (cracks in the sidewalk)
Use the rules of stratigraphy to describe what they see.

Resources

Milwaukee Public Museum | Stratigraphy: This page describes the principles of stratigraphy.
Iowa PBS | Exploring Iowa's Coldwater Cave, Winneshiek County, Iowa: A video from Iowa PBS exploring Coldwater Cave.
PBS LearningMedia | Regents Review 2.0: Erosion: This video segment explains both erosion and deposition.

Contributors

Media courtesy of Dr. Josh Sebree, University of Northern Iowa.

Contributed by Bailey Bushman with support from the Coldwater Cave Project.