ISS020-E-9861 Click the photo number to access all resolutions available and the database record.
The Fold is a geologic structure called a monocline—layers of generally flat-lying sedimentary rock with a steep, one-sided bend, like a carpet runner draped over a stair step. Geologists think that monoclines on the Colorado Plateau result from faulting (cracking) of deeper and more brittle crystalline rocks under tectonic pressure; while the crystalline rocks were broken into raised or lowered blocks, the overlaying, less brittle sedimentary rocks were flexed without breaking.
The portion of the Waterpocket Fold illustrated in this image includes layered rocks formed during the Mesozoic Era (about 250 – 65 million years ago). The oldest layers are at the bottom of the sequence, with each successive layer younger than the preceding one going upwards in the sequence. Not all of the Fold's rock layers are clearly visible, but some of the major layers (units to geologists) can be easily distinguished.
The top half of the image includes the oldest rocks in the view: dark brown and dark green Moenkopi (Trm) and Chinle (Trc) Formations. Moving toward the foot of the mesa, two strikingly colored units are visible near image center: light red to orange Wingate Sandstone (Jw) and white Navajo Sandstone (Jn). Beyond those units, reddish brown to brown Carmel Formation (Jc) and Entrada Sandstone (Je) occupy a topographic bench at the foot of a cliff. The top of the cliff face above this bench—Big Thomson Mesa—is comprised of brown Dakota Sandstone (Kd). This sequence represents more than 100 million years of sediments being deposited and turned into rock. Much younger Quaternary (2-million- to approximately 10,000-year-old) deposits are also present in the view.
The area shown in this astronaut photo is located approximately 65 kilometers (about 40 miles) southeast of Fruita, Utah, near the southern end of Capitol Reef National Park.
