The Northeastern Strawberry Valley Quadrangle embraces approximately 240 square miles of the area where the south-central Wasatch Mountains meet the southwestern flank of the Uinta Mountains and form the northwestern boundary of the Uinta Basin. This report concerns the stratigraphy and structure of this geologically important region, with an accompanying geologic map depicting for the first time the features on an adequate scale.

An aggregate thickness of 38,000 feet of sedimentary strata, in age from Upper Pennsylvanian through Eocene is exposed within the area. Most of the sediments are marine. A few thousand feet of andesitic volcanics of Oligocene or Miocene age overlies the older strata in a few places. In addition, portions of the area were modified by Pleistocene glaciation.

From the standpoint of structural geology, this area is of great interest for it lies at the locus of the east-west-trending Uinta Mountains and the north-south Wasatch Mountains. Geologic mapping proves that overfolded strata of the south-central Wasatch Mountains allochthon were thrust some tens of miles eastward upon the foreland of the flat to gently inclined strata of the southwestern Uinta Mountains. The uparching and ramp thrusting of the Uintas occurred after the east-west thrusting, followed by high-angle normal faulting, uplift, and tilting.

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