2009-05-19_REVISION - M1977285 (28)

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Hydrogeological Evaluation of Sunday Mines Group Geologic and Hydrologic Conditions ¦ Cretaceous Mancos Shale; and ¦ Unconsolidated Quaternary deposits. The Permian Cutler Formation directly overlies the Hermosa Formation, and consists predominantly of arkosic sandstone and conglomerate. Small quantities of sandy shale are present within the formation. The formation has an estimated thickness that approaches 3,000 ft. The Culter Formation is overlain by the Upper Triassic Chinle Formation. This unit consists primarily of siltstone interbedded with fine grained sandstone, shale and conglomerate. The individual lithological units within the formation are lenticular and discontinuous. This unit is commonly 500 to 600 ft. thick, but the unit thins along the flanks of the Gypsum Valley Anticline. The Chinle Formation is overlain by the Jurassic Glen Canyon Group, which consists of three formations: the Wingate Sandstone, the Kayenta Formation, and the Navajo Sandstone. The Wingate Sandstone overlies the Chinle Formation. This formation consists of massive, fine grained sandstone composed of clean well-sorted quartz sand grains. The unit contains vertical joints that extend the entire thickness of the formation, which contributes to cliff formation in the project area. The Wingate sandstone forms the large cliffs present on the north side of Big Gypsum Valley. The Kayenta Formation overlies the Wingate Sandstone and consists of interbedded sandstone, siltstone and shale. The sandstone is thin bedded, flaggy to massive, and occurs in discontinuous beds that interfinger with siltstone and shale. The thickness of the Kayenta Formation ranges from 180 ft. to 210 ft. The Navajo Sandstone is massive fine-grained clean quartz sandstone, which overlies the Kayenta Formation. This unit is eolian in origin as evidenced by very large tangential cross-bedding. The formation is approximately 400 ft. thick in the project area. The Glenn Canyon Group is overlain by the Jurassic San Rafael Group, which includes three formations: The Carmel Formation, the Entrada Sandstone, and the Summerville Formation. The Carmel Formation overlies the Navajo Sandstone and consists of a variety of clastic sedimentary rocks including siltstone, shale, and sandstone. This unit is relatively thin with an estimated thickness of 10 to 25 ft. The Entrada Sandstone overlies the Carmel Formation. This formation consists of a combination of horizontally bedded and eolian-type cross bedded sandstones with a bimodal grain size distribution including very fine grained sandstone (<0.0001 inches (in.) grain size) and medium grained sandstone (0.02 to 0.03 in. grain size). The Entrada Sandstone is 110 to 120 feet thick. • cm 2-3 T:\64986-Denison Mines\Task Order 3 - DMO Sampling and Analysis Plan\Task 3.14 - Hydrogeology ReportVinal Sunday hydro reporNeXITINAL Sunday Hydrogeology Reporl.doc