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4200 The reservoir is contained primarily within the Permian- Pennsylvanian-age Maroon and Minturn formations and the Pennsylvanian-age Belden formation which are mostly shales, siltstone, limestone, and sandstone. However, there is a large mass of evaporites upstream of the dam's right abutment and a smaller outcropping upstream of the dam's left abutment within the reservoir area. These outcrops apparently represent a diapir probably formed during the Laramide Orogeny. The evaporites are gypsum and anhydrite of the Eagle Valley formation. These formations are blanketed with varying amounts of unconsolidated material. . The North Side and South Side Collection Systems are or will be constructed in Precambrian granitics and metasediments which are primarily granite gneiss and lesser amounts of porphyritic granite gneiss and schists of the Sawatch Range. The diveraion structures and the delivery conduits are located in glacial moraines or glacier-related alluvium. Sugar Loaf Dam and Turquoise Lake Lake Fork of the Arkanaas River. on morainal deposits which are in are located in the glaciated The dam and lake are located excess of 100 feet deep. Mt. Elbert Conduit, Forebay, and Pumped-Storage Powerplant, Twin Lakes Dam and Reservoir, Otero Canal, Otero Powerplant, Clear Creek Dam and Reservoir, and the Mt. Elbert-Malta Transmission Line are all located within the wide breach formed by the Arkansas Valley. This portion of the valley is considered to be a graben or down-dropped valley formed during the Laramide Orogeny. The crystalline Sawatch and Mosquito Ranges were uplifted, and the Arkansas Valley became a dOwn-ULuPpcd block (faulted on both sides). Then during Pliocene, the deep valley was filled by coale~Llng alluvial fans originating from the two ranges. These sediments comprising the Dry Union Formation are presently estimated to be in excess of 800 feet and could possibly be 3,000-4,000 feet deep. The upper portion of the Dry Union Formation consists of sandy silt and interbedded silty gravels while the lower portion is a compact silt and clay. Glaciation and recent fluvial modifications have taken place leaving thin veneers of additional deposits on the surface of the Dry Union Formation. . Mt. Elbert Conduit, Mt. Elbert Forebay, and Mt. Elbert Pumped-Storage Powerplant will be constructed on the reworked samples of the Dry Union Formation except for short reaches 111-13 .