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4~ 41 <br />4.4.4 MAP UNIT DESCRIPTIONS <br />• MAP UNIT: AW -ALLUVIAL LAND, 0 TO 5 PERCENT SLOPES <br />This map unit is on nearly level flood plains and stream channels. The slope is 0 to 5 <br />percent. The native vegetation is mainly agreasewood-shrubland community. These soils are <br />mainly members of the mixed, frigid family of the Ustic Torrpsamments. <br />Included in this map unit is about 10 percent Rivra gravelly sandy loam variant and about 5 <br />percent Havre loam adjacent to stream bank. Included areas make up about 15 percent of the <br />total acreage. <br />Typically, the surface layer of the alluvial soil is alight brownish gray, loose, fine sandy loam <br />about 2 inches thick. The substratum is stratified pale brown, single grained, very fine sand and <br />medium sand about 48 inches thick. <br />Permeability of the alluvial soil is moderately rapid. Available water capacity is moderate to <br />moderately low. Effective rooting depth is 48 inches. Runoff is high and the erosion hazard for <br />water is severe. Wind erosion hazard is high. <br />The unit is mainly used for wildlife habitat. <br />• The present plant community is mainly greasewood, cottonwood, big sage, rabbit brush, <br />burdock, gum weed, cheat grass, and western wheat grass. <br />A representative profile of an alluvial fine sandy loam, sample point MU 15, 310 feet west <br />and 20 feet north of the center of Section 29, T 7 S, R 102 W at an elevation o 5,250 feet is: <br />Al 0 to 2 inches; light brownish gray (2.5 Y 6/2) fine sandy loam brown (10 YR 5/3) <br />moist; weak very thin platy parting to fine single grained structure; loose, non-sticky, <br />and non-plastic; calcareous; few fine roots; pH 8.3; gradual smooth boundary. <br />C1 2 to 48 inches; pale brown (10 YR 6/3) stratified very fine sand to medium sand, <br />brown (10 YR 5/3) moist; fine single grained structure; loose, non sticky, and <br />non-plastic; calcareous; few fine roots; pH 8.1. <br />Sandstone bedrock is encountered below about 30 inches in some pedons. <br />MAP UNIT: DL•DISTURBED LAND, VARIABLE SLOPES <br />This map unit is on Hearty level to very steep slopes. The slope range is 0 to 55 percent or <br />more. The existing vegetation is mainly weeds and grasses. Typically, the surface layer of the <br />• disturbed soil includes some (20 to 35 percent) road fill material and averages about 4 inches <br />thick but may range to 18 inches. <br />M~ Volume 1 4-29-96 <br />