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<br />- 27 - <br /> <br />sandstone bedrock. <br /> <br />The upper slopes of the Elk Mountain area contain numerous springs <br /> <br />and extensive seepage areas that emerge between fractured sandstone beds <br /> <br />and underlying shale strata. Outflow from the springs and seeps main- <br /> <br />tains a streamflow in the ravine~ through most of the year. The ravines <br /> <br />contain numerous reaches that ar~ choked with lag deposits of coarse <br /> <br />sandstone rubble lying at a precarious angle of repose. This combina.- <br /> <br />tion of conditions which inc1ude~ abundant groundwater seepage into <br /> <br /> <br />relatively thick colluvial soils overlying bedrock on steeply inclined <br /> <br /> <br />contacts, and daylighting of the soil cover by numerous deeply incised <br /> <br /> <br />ravines, all add up to a classical situation for debris avalanche pro- <br /> <br />duction. <br /> <br />The east-facing slope of Elk Mountain also contains three large and <br /> <br />active snow avalanche paths which are marked by "pushed" and stunted <br /> <br />brush cover, and scattered rock debris. The southernmost of these (3c) <br /> <br />has quite evidently discharged to a point immediately adjacent to the <br /> <br />mountain meadow described in the previous section. This is illustrated <br /> <br />in the photograph of figure 11. <br /> <br />Old Landslide Terrain Below Gallo Bluff (3d) <br />A large area of old landslides extends from the base of Gallo Bluff <br /> <br />,south to the mudf10w fan, and east to an area of Mancos Shale bedrock <br /> <br />near the west bank of the main channel of Carbonate Creek. A large part <br /> <br />of this was delineated on the USGS Geologic Map by Gaskill and Godwin, <br />and additional areas of landslide debris and terrain were mapped by photo- <br />geologic study and field reconnaissance during our investigations. The <br /> <br />surface of this area lacks the uniform general slope of the major mudflow <br />