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Cenozoic wind and freshwater deposits. Its higher elevations are supported by older rocks of <br />Mesozoic and Paleozoic sediments, or Tertiary intrusions (Young and Young 1977:51 -52). <br />The project is within a wide, open valley bottom between Timberlake and East <br />Timberlake Creeks. The terrain is rolling and is characterized by low to moderate relief; <br />elevation averages about 6640 feet within the study block. Bedrock is the main body of the <br />Wasatch Formation (Paleocene) alluvial deposits, chiefly claystone and gravel. Claystones <br />weather to form badland topography. The gravel deposits cap higher elevations and give the <br />terrain a gently rolling character. Reworked and redeposited Paleocene gravel along <br />Timberlake Creek and its two major tributaries, East and West Timberlake Creeks, is mapped <br />as Quaternary alluvium by Tweto (1979). These hydrologic resources border the study area. <br />Farther from the proposed project, the main drainages include the Little Snake River to the <br />north and the Yampa River to the south. <br />Late Quaternary deposits are mainly aeolian and alluvial, and correlatable sequences <br />occur over a broad region of the mountain west, the western plains and Colorado Plateau <br />(Miller 1992, in prep.). The aeolian deposits are typically sheet and shadow deposits that <br />drape over the landscape. Sheets are laminar bedded; shadows differ from sheets in that they <br />thicken leeward of topographic high points; however, they grade into sheets to leeward and <br />windward. <br />Normally there are four individual aeolian sheet deposits separated by unconformities <br />which represent lacunas — i.e. periods of erosion rather than periods of non - deposition as in <br />the case of hiatuses. The upper three sheets are relatively unweathered and age to about 3000 <br />years ago and later. The lower sheet normally represents deposition in the latest Pleistocene- <br />earliest Holocene, and in middle Holocene in aeolian depositional environments, or middle <br />Holocene alone overlying latest Pleistocene and early Holocene alluvium. The early part of <br />the deposit is coeval with Folsom and Goshen times; Mill Iron site in southeast Montana, <br />Upper Twin Mountain site in Middle Park of Colorado are Goshen sites contained in these <br />deposits, while Finley and Casper sites in Wyoming, and Jerry Craig site in Middle Park of <br />Colorado are Cody complex sites contained in these deposits. The latter part was deposited <br />between 6500 and 4500 years BP; north of the border in Wyoming, 48S WI 153 produced a <br />6300 years BP age near the base of the deposit. <br />The lower deposit is well indurated by syndiagenetic or in -place weathering and is <br />identified by secondary minerals formed during weathering which include calcite, sulfides, <br />iron oxy- hydroxides, manganese oxides, smectite clay, and zeolites. In surface exposure, the <br />weathered deposit is light colored and resistant to weathering, especially deflation. Middle <br />Archaic artifacts most commonly occur on or just below the unconformity that marks the <br />upper contact of the deposit. <br />Alluvial deposits consist of three sets of deposits. The oldest is latest Pleistocene and <br />early Holocene in age, roughly 13,000 years ago to about 7500 years ago. The source of <br />2 <br />