Faulted Sedimentary Rock Layers, Guatemala

Photograph copyright J.K. Nakata, August, 1988

Photograph of faulted sedimentary rock layers exposed in a roadcut in Guatemala. The sedimentary rocks originally were deposited as horizontal layers of sand and gravel in streams and debris flows.

After their deposition, the consolidated sediment was broken by a moderately-dipping normal-slip fault that has dropped layers left of the fault down about 3 meters relative to layers to the right; note the small subsidiary fault that dips even more shallowly and joins the main fault above the person’s head.

These kinds of relations are common where rocks of the earth’s crust are stretched and pulled apart (extended), yielding faults like these that have normal dip-slip geometry.

Photo Copyright © J.K. Nakata, August, 1988/USGS