Laserfiche WebLink
reserves of the study area. This shallow, broad syncline is a simple fold with gently <br /> dipping flanks. <br /> The Cretaceous-age Dakota Sandstone is the youngest formation found in the study area, <br /> with the exception of Quaternary deposits. The overlying upper Cretaceous Marcos shale (a <br /> soft, homogeneous, dark-gray fissile rock) is not found in the study area. The Dakota <br /> consists primarily of resistant yellowish to gray, fissile sandstone, and conglomeratic <br /> sandstones interbedded with dark gray carbonaceous shales, impure coal , and a basal <br /> conglomerate. It forms resistant but thin sandstone ledges that are scattered throughout <br /> the study area. These ledges are often exposed at the surface or are encountered within a <br /> few feet of the surface. <br /> The deposits of Quaternary age consist of wind deposited material , streamlain alluvium, <br /> and local slopewash. Deposits of a light-red sandy loam and loam loessial material mantle <br /> the nearly flat mesa-like surface on the west side of the study area. <br /> Soils and Geomorphology. The study area occupies the gently sloping western portion of <br /> "First Park," an irrigated area adjacent to Nucla on the east, south, and west. Ephemeral <br /> drainages generally cross the study area from northeast to southwest. Numerous small <br /> ponds have been created along many of these drainages. Tuttle Draw is to the north and <br /> only drains a small portion of the northwest corner of the study area. Calamity Draw <br /> flows from east to west along the southern border of the study area. Sewage lagoons for <br /> the town of Nucla are located adjacent to Calamity Draw. Many of the irrigation ditches <br /> which cross the study area empty into Calamity Draw. <br /> Haplaquoll soils were found on the ephemeral drainages. These soils have a dark surface <br /> layer with much organic matter. They are wet throughout most of the soil profile for much <br /> of the year. Three soil families of Haplaquolls were mapped. One was 20 to 40 inches to <br /> bedrock and had a sandy loam texture with less than 18 percent clay. The second soil <br /> family was greater than 40 inches to bedrock and had sandy loam and loam textures with <br /> greater than 18 percent clay in the particle size control section. A third soil family <br /> was found on narrow wet areas adjacent to sandstone ledgerock. This family was less than <br /> 20 inches to bedrock and had sandy loam, loam, sandy clay loam, and silty clay loam <br /> textures. Soil series names do not presently exist for these soil families because the <br /> soil wetness, which is a diagnostic factor in the taxonomic classification, is artificial <br /> due to the presence of ample irrigation water. The Soil Conservation Service (SCS) has <br /> 9-5-6 Revised 04/11/88 <br />