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Show central Utah-- the Middle Rocky Mountains and the Basin and Range provinces - and borders a third, the Colorado Plateau. The Unit area involves two major mountain ranges, the east- west trending Uinta Mountains and the north- south trending Wasatch Mountains, and adjacent valleys0 The geologic composition of the area is complex and includes sedimentary, igneous and metamorphic rocks ranging in age from Pre- Cambrian through Quaternary. The region is a part of the great Rocky Mountain Cordilleran Zone, which has been involved in recurring major structural deformation from Pre- Cambrian time through late Cretaceous ( Laramide deformation) and early Tertiary time with severe deformation, overturning, and faulting of the Wasatch Mountains and the contemporaneous upfolding and faulting of the Uinta Mountains. The rocks of the Great Basin area were subjected to Basin and Range type block faulting in later Cenozoic time resulting in the present landforms of alternating, north- south trending mountains and valleys0 Several periods of intense extrusive and intrusive igneous activity occurred in the Wasatch Mountains during Tertiary time. The Uinta Mountains were arched upward with the south flank of the uplift forming the north limb of the asymmetrical Uinta Basin syncline, which structurally as well as topographically is a large shallow downwarp. The Uinta range and many parts of the Wasatch range were subjected to repeated Pleistocene glaciation, producing steep sided " U"- shaped valleys, morainal features, sharply carved peaks, and extensive piedmont deposits. Subsequent to the glacial activity other erosional agents have altered the sculptured topography. Mass wasting was particularly active and numerous slumps, landslides and talus accumulations are conspicuous o b. Local Geology Along the Strawberry Aqueduct System The 37- mile- long Strawberry Aqueduct would be a series of tunnels, pipelines, siphons, dams, and diversion structures. It would begin at the headworks at Upper Stillwater Reservoir in the PreCambrian Uinta Mountain group of quartzite and minor shale and would encounter progressively younger formations of shale, limestone, sandstone, and conglomerates downstream. The Aqueduct would end at the enlarged Strawberry Reservoir in the Tertiary Uinta formation. Most formations involved in the various features are exposed for study along the proposed aqueduct alinement. The rock formations dip from a few degrees to as much as 60 , generally southward, and strike generally 116 |
