Analyze this outcrop, photographed by geologist, Thomas McGuire. It is another natural geologic cross section with red sandstone layers on the bottom and a yellow conglomerate (graved) rock layer on top. Notice that the red rock layers are not horizontal. They are bent up on the left and right, and down in the middle, as wave-like folds (like a crumpled rug).

1. Using a pen, trace two of the contacts between layers of the red sandstone as well as you can. Assuming that the red sandstone layers were originally horizontal, what may have caused them to be folded in this way?

2.

On both sides of the picture, use an arrow to level the exact location of the contact between the red sandstone and the horizontal yellow conglomerate above it. This surface is an unconformity ? a surface (contact) representing erosion of layers or a break in deposition of layers, like a place where pages are missing form a book. Something happened at the time represented by the surface, but no rock layer remains as a record of the even. What sequence of events may have happened to form the unconformity?

Answer rating: 100% (QA)

1 The reason why the rock is folded in this way is due to the s... View the full answer