Laserfiche WebLink
RESIILTS <br />Geolocxv <br />The site occurs on an abandoned river meander where the <br />Green River has eroded into an adjacent terrace. The terrace is <br />bedrock cored, most likely Mancos Shale, and has a Quaternary <br />alluvium cap of approximately 10 m thickness. This thickness of <br />alluvium is apparent in gravel pits excavated into the terrace <br />for commercial purposes, and also by the vertical distance <br />between the terrace surface and a line of springs which erupt <br />from the terrace escarpment slope. <br />Snowmelt, rain and irrigation water percolate through the <br />coarse-textured alluvium and contact the shale which is an <br />impermeable layer. The water then flows west on top of the shale <br />and erupts as a line of springs on the terrace face. The <br />groundwater leaches salts from the shale resulting in waters with <br />high salt concentrations in certain areas. <br />The bedrock core appears to extend from the study area to <br />the east under the entire peninsula. Thus, groundwater recharge <br />in this area by the Green River is not possible. <br />Site History <br />Site history has been determined from examining aerial <br />photographs and by discussions with the Escalante Ranch owner, <br />Ross Healy. Each photo year is discussed below. <br />Pre-photographs years. Our interpretation of the study area <br />prior to the 1937 photographs are derived from on site <br />observations of human habitations as well as discussions with <br />Ross Healy. Mr. Healy told us that the wetland area has been <br />inhabited since the late 1800's and the Green River dike has been <br />in place since that time. On the ground there are at least two <br />wooden structures that appear to be homes, as well as a barn and <br />hay rack. People definitely lived in the bottom area and cut hay <br />from this site. It is doubtful that the site was plowed as the <br />contours are those created by river bars. The presence of these <br />homes and equipment indicate long-term inhabitation and <br />relatively little flooding or standing water. These structures <br />are in a high area, but are today surrounded by water in early <br />summer. Most likely the inhabitants cut natural hay from <br />relatively dry to moist meadows. No traces of these meadows <br />occur today. <br />1937. At this time there was little irrigated agriculture <br />on the terraces to the east. The water year in which this <br />photograph was taken was a low runoff year for the upper Colorado <br />4 <br />