Interim geologic map of the Dairy Ridge quadrangle, leading margin of Willard thrust sheet, Cache, Rich, and Weber Counties, Utah (OFR-479)

By: J. C. Coogan The Dairy Ridge and adjacent Horse Ridge quadrangles are located northeast of Ogden, Utah and southeast of Logan, Utah, in the southern Bear River (Monte Cristo) Range in Cache, Morgan, Rich, and Weber Counties, Utah. The range is the source of snow-melt runoff used in Utah and Idaho, and is largely unpopulated. Geologically the quadrangles are on the leading edge of the Willard thrust sheet, the western and older of several such sheets in the ?overthrust? belt of Utah, Idaho, and Wyoming. Strata on this leading edge of the thrust sheet are noticeably thinner and lithologically different than on the trailing edge of the thrust sheet, as exposed near Ogden and on the west side of the Bear River Range near Logan. Specifically, Proterozoic strata lack the key marker beds present in the Huntsville area, making correlations suspect. In the Dairy Ridge quadrangle, the leading edge of the Willard thrust sheet is marked by Proterozoic and Cambrian Geertsen Canyon Quartzite jux