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<br />Geophysical studies near Yellow Creek by Campbell (1977) suggest that <br />~~ fracturing and/or faulting associated with the Dudley Bluffs system may be <br />present. Although il: is probable that fractures and minor faults associated <br />with the Dudley Blut'fs system cross the southwestern corner of the lease <br />area, it is not clear at the present time what significance they may have. <br />It is not anticipated that they will affect commercial exploitation of the <br />lease area (Cole 198:3). <br />6,1.3 Area Lithology <br />As stated above, there are five major formations within the project area. <br />The unit where minir~g will concentrate is the Green River Formation. This <br />formation has been subdivided into three members: the Douglas Creek Member, <br />the Garden Gulch Member, and the Parachute Creek Member. Figure G-4 shows a <br />general stratigraphic column of the lease area. <br /> G,1.3.1 Douglas Creek and Garden Gulch Members <br />r <br />S~ The Douglas Creek Member consists of interstratified siltstone, shale, and <br /> channel-form fluvial sandstone and is best exposed along the southwestern <br /> flank of the basin. The Garden Gulch Member conformably overlies the <br /> Douglas Creek, and consists primarily of marlstone, lean clay-rich oil <br /> shale, and algal limestone. The Garden Gulch is recognized throughout the <br /> interior of the basin, however, the Douglas Creek generally is not. In the <br /> Basin's depocenter, Johnson (1979a, 1979b) has identified a thick assemblage <br /> of lacustrine rocks which have not been formally named (i.e., the "Unnamed <br /> Member"). The Unnamed Member possibly correlates in time with parts of the <br /> Douglas Creek and Garden Gulch Members in the southwest part of the basin. <br /> A similar facies transition also occurs along the southeastern and eastern <br /> margins of the basir~. At these localities, the lower Green River Foramtion <br /> consists of a thick interstratified series of sandstone, fresh-water <br /> limestone, and gray shale. Donnell (1961) calls this unit the Anvil Points <br /> Member and correlates it with the combined Douglas Creek and Garden Gulch <br /> Members and part of the lower Parachute Creek Member, <br /> <br /> <br />G-6 <br />