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Show Currant Creek Dam would be located in Mesaverde and Currant Creek formations. The Mesaverde formation would form the left abutment and most of the reservoir area. This formation consists of a series of alternating sandstone and shale layers„ The right abutment would be composed principally of conglomerate which is part of the Currant Creek conglomerate formation. Overburden consists of silty to clayey sand and gravel and varies in depth from 0 to 75 feet and will average about 40 feeto Extensive drilling has been done by the Bureau of Reclamation in the proposed damsite and reservoir areas. This drilling and associated testing of the foundation and water levels indicate the damsite would be competent and the reservoir basin water tight. Local Geology-- Jordan Aqueduct Most of the Jordan Aqueduct alinement is located on deep, unconsolidated material consisting of Lake Bonneville sand and gravel terraces. ^ These terraces have been reworked in some areas to form low alluvial fans. About 2 miles of the Aqueduct was constructed in lake bed sediment containing enough salt to prohibit agriculture. Rock excavation was encountered across a boulder field about one and a half miles wide. A small amount of well- cemented andesite conglomerate and tuff outcrops were near the surface through this reach. All trench excavation for the Aqueduct was dry except for about 2,500 feet where the Aqueduct crosses the Jordan River. Geologic reports have been prepared on all proposed features of the Unit. These reports are available for reference at the Bureau office in Provo, Utah. Some of these reports are referenced in the bibliography of this statement. Local Geology-- Jordanelle Dam and Reservoir Jordanelle Dam and Reservoir would be located on the Provo River at Jordanelle in a complex geologic environment. The proposed sites are within the transitional zone between the Wasatch and Uinta Mountain ranges. The area is one of uplift and intrusion of large igneous stocks, followed by lava flows, blowouts of volcanic ash and agglomerate, faulting, introduction of hydrothermal solutions with associated mineralization of some zones and extensive alteration, extensive erosion, and deposition of thick overburden materials. The dam and the major portion of the reservoir site would be underlain by Tertiary volcanic rocks. They are composed of andesite flows, tuffs, and ashy agglomerate outcrops of 119 |