Geological Survey Circular 217 Preliminary Report on the White Canyon Area, San Juan County, Utah

The sedimentary rocks of the White Canyon area dip 1° to 3° SW., except in the western part of the area, near the Colorado River, where the dips steepen. The upper beds of the Organ Rock tongue and the lower beds of the Moenkopi formation have been folded into minor flexures in the western part of the mapped area.

The rocks in the different formations are strongly jointed, especially in the western part of the mapped area. Many of these joints are traceable from the top of the Moenkopi formation through the Organ Rock tongue and the Cedar Mesa sandstone member of the Cutler formation in the bottom of the canyon. Just northwest of the mapped area some similar fractures, which displace beds of the Cedar Mesa sandstone member, appear to be faults.

The three most prominent joint systems trend due east, N. 65°-75° W., and N. 65°-75° E. All have vertical dips. The Organ Rock tongue and the Moenkopi formation have been bleached in a zone as much as 3 feet wide along some of these joints. Less prominent joints, also with vertical dips, strike nearly north.

Fractures in the sandstones in the Shinarump conglomerate trend generally parallel to the main jointing in the area. A few inches to a foot of movement has taken place along some of these fractures.