Three sedimentary rock layers are exposed at Devils Tower National Monument: the Spearfish Formation, the Gypsum Springs Formation, and the Sundance Formation. When you visit Devils Tower National Monument, you can see these layers by hiking along the Red Beds Trail. View them now by selecting a panorama taken from this trail.
In the photo select the names of the three layers in turn. You should start at the bottom with the Spearfish Formation and work your way to the top. Remember that older sedimentary rocks lie beneath younger sedimentary rocks.