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Much of the river corridor's scenic beauty stems directly from the spectacular geology of the various canyon segments. The Dolores generally flows from south to north in a deep canyon that is interrupted only where the river crosses Gypsum and Paradox Valleys. A series of anticlinal and synclinal valleys result from a sequence of northwest-trending folds within the area. Forma- tions exposed along the corridor range from the Morrison Formation of Jurassic age to the Moenkopi Formation of Triassic age. The nature of the Dolores Canyon changes significantly downstream from Gypsum Valley. The upper segment (Bradfield Bridge to Disappoinunent Creek) is characterized by an average gradient of 24 feet per mile and sloping canyon walls covered with oakbrush, pinyon/juniper and tall ponderosa pines in the uppermost reach. The portion immediately below Gypsum Bridge changes to an average gradient of 11 feet per mile within a deeply-cut, extremely meandering slickrock canyon bearing predominantly pinyon/juniper and cactus-type vegetation on the canyon slopes. This meandering portion of the canyon was identified by BLM as a Wilderness Study Area in 1980 and was later recommended by BLM for actual "wilderness" status. In 1987, the Bureau of Reclamation (USBR) completed construction and filling of McPhee Figure 2, Upper Dolores River. Figure 3, Confluence with Disappoinunent Creek generally separates upper and lower reaches of Dolores River. 10 Dam (Figure 5) and Reservoir as part of its Dolores Project, a partici- pating project of the overall Colorado River Storage Project. Storage capacity of the reservoir is 381,000 acre-feet. Water pumped from McPhee will eventu- ally be used primarily for irrigation; municipal and industrial uses will be secondary. Additionally, downstream river releases will provide some fish and wildlife enhancement, as well as recreational opportunities.