#anticline

The Waterpocket Fold is an anticline, a geologic feature formed when rocks are folded upwards. You may note that this is a valley, a surprising landform to find if the rocks have been folded upward, but there is one more detail that controls the shape of the valley we see. When rocks fold bend, the rocks at the hinge of the fold are put under stress. The rocks at the widest part of the fold are pulled apart and the rocks at the core of the fold are squeezed. Both of these cases – rocks under tension and compression – can cause the rocks to fracture. When cracks form, water can get into the rocks and erode them away. Large anticlines commonly are found with their cores eroded away because those rocks are fractured and easily eroded, while the tilted hinges remain in tact as exposed, dipping layers, just as seen here. The exposed rocks are Jurassic and Cretaceous aged sedimentary rocks, marking times from when the U.S. Southwest went from being a desert filled with sand dunes to a time when it was submerged beneath the waters of an inland seaway. -JBB Image credit: USGS/Ida & Leo https://flic.kr/p/wYcF4x Read more: http://www.nps.gov/care/learn/nature/geology.htm