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4-7 GEOMORPHIC CRITERIA • ALLUVIAL SEDIMENTS OF EAST SALT CREEK The alluvial sediments of the East Salt Creek comprise the single, most important geomorphic unit in the area. They comprise awell-definable, wide strip of sediments that can be clearly distinguished from other geomorphic units. The channel of the creek is usually eroded into these deposits; the creek usually flows at the elevation between 10 to 20 feet below the surface of the river terrace. Because of this deep erosion, the active flood plain is absent in most cases. R is developed only locally and in a very limited width. The remaining part of the alluvium was formed by a distinct terrace that comprises a former flood plain which, apparently, is no longer being constructed by the river. There are no accurate data available on the thickness of the alluvial deposits of the east Salt Creek. According to the results of ground water monitoring well installation, the thickness is more than 80 feet. Exploratory drilling performed north of the site for other purposes determined the thickness of the deposits to be more than 100 feet. • OTHER ALLUVIAL SEDIMENTS As indicated on Fgure 4.1 east side of East Salt Creek, t Munger Creek Canyon on the two unnamed valleys of a very All four valleys are filled w limited width and can be trace The alluvial deposits in Mc mile from its confluence with E followed for a long distance (a Salt Creeks. It is evident from the geom and of the unnamed creek on deposits of the East Salt Cree • of East Salt Creek; the valley s AVF above and below the conf M~ -2, there are four identifiable side valleys within the area. On the hey are represented by McClane Canyon in the north part and by south side. Located on the west side of the valley floor, there are similar character. ith soils that can be classified as alluvial deposits. They are of a d a limited distance from the main valley. Clane Canyon extend to a distance of only about a quarter of a ast Salt Creek. The alluvial deposits in Munger Canyon can be pproximately one mile) from the confluence of Munger and East orphic point of view that the alluvial deposits of McClane Canyon the other side of the valley are distinctly higher than the alluvial k. The outwash of both these canyons covers the alluvial deposits urface is distinctly higher at the confluence than the main valley luence. Volume 1 4.29-96