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I -s- -,- . mately parallel. The precambrian crystalline rocks forming the core of the range are intensely fractured and sub-divided into many small blocks by numerous faults. The Gore Fault can be easily identified in the field, as it is highly visible traversing through the area east of the top of Vail Pass, then northwestward through Main Gore Creek just upstream of the confluence with Black Gore. ~estward of the fault, the sedimentary rocks of the Minturn and Maroon Formations are very evident. The Minturn Formation can be identified by the distinctive beds of coarse grained gray to reddish sandstones, conglomeratic sandstone, sandy and silty shales as well as the pinkish gray to gray limestone beds. The Maroon Formation confonm~bly overlies the Minturn Form~tion.. The Maroon Formation consists of red mudstone or shale, siltstone and fine-grained sandstone. The Maroon Formation is in depositional Formation. The sections of tne side tributaries that pass through these more resistant members are typified by very steep gradients and during the late Pleistocene period a~ the valley floor near the Town of Vail at some time in the past has been much deeper. The alluvial deposits within the valley currently exceed 100 feet in depth and are interfingered with coarser side tribut~ry talus and slope wash deposits. Layers of peat or high organic content layers are found at infrequent levels throughout the alluvium. The upper end of most of the side tributaries. such as Booth, Pitkin on the north side of the basin and numerous smaller tributaries on the south side of the basin are formed in bowl-shaped depressions that were created by "hanging" glaciers or nivation hollows during the Pleisto- cene period. The lower levels of the bowls are founded on erosion resistant or harder sandstone or limestone members of the Minturn contact with the granitic Precambrian crystalline 16 River along the Gore Fault. rocks near the upper series of cliffs. end of the Piney There are various locations through the valley where large mass wasting or rock-soil slides have occurred. Many of these are a~~nciat~d with downward dipping or badly jointed shale or mudstone layers that provided planes of weakness. Vegetal Cover The vegetal cover aspects of the basin and sub-basins have been derived from the U.S.G.S. Quad maps and material supplied through INSTAAR which was obtained from high altitude aircraft photo work of both color infrared and standard black and white imagery. The INSTAAR The Minturn Formation is well exposed in the vicinity of Red Sandstone Creek and is the oldest sedimentary rock in the area.16 It . ;s composed of med;um to very coarse-grained. gray to reddish brown sandstone, conglomeratic sandstone, thin beds of reddish brown silt- stone and sandy silty shale and pinkish gray to gray limestone beds. Gore Creek has eroded deeply into the Minturn Formation by a co~bination of glaciation and alluvial action. The basic valley shape through much or the n'~ ill Gore Villley is the classIc U-shape typlcal of glacier action. This glacial erosion occurred mainly vegetation ~apping categories included the following nine major classifications: - . 1 .) J . ~' " , i -