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Qago Older alluvial gravels (middle Pleistocenel: <br />• poorly sorted, rounded to subrounded, poorly <br />consolidated gravels in a fine-grained <br />matrix. These older gravels have a slight <br />increase in consolidation, slightly greater <br />weathering of igneous detritus, and a greater <br />accumulation of calcium carbonate in the C <br />horizon than the younger gravels. The <br />deposits are subject to sheet flooding and <br />erosion. <br />Qpg Pediment gravels (early Pleistocenel: Old, <br />high-level alluvial gravels that have an <br />abundant accumulation in the C horizon and a <br />higher percentage of weathered igneous-rock <br />fragments than the younger gravels. The <br />gravels form nearly planar surfaces that are <br />subject to sheet flooding and erosion. <br />QTa High-level alluvium (Ouaternary/Tertiary].: <br />bouldery alluvial deposits that form nearly <br />planar, gently sloping surfaces high above <br />modern streams. The location and occurrence <br />of the deposits above modern streams and <br />similarity to previously mapped deposits <br />(Tweto and others, 1976) suggest formation <br />during the Tertiary or early Quaternary. <br />• These deposits are subject to sheet flooding <br />and erosion. <br />Colluvial Deposits <br />Qls Landslide deposits (Holocene to late <br />Pleistocenel: a heterogeneous assemblage of <br />unconsolidated soil and/or rock formed by <br />slow to rapid downward and outward mass <br />movement in response to gravitational stress. <br />These deposits, which include earthflows, <br />usually form an irregular, hummocky <br />topography and may have an associated main <br />scarp. Relative age of the deposits is noted <br />by subscripts (1 is the youngest). Qlsl <br />deposits most likely were formed during the <br />Holocene and Qlsz and Qls, deposits probably <br />were formed during the Wisconsin glacial <br />stage. <br />• P6MITAPPLIGTI011 EXH-12 - 11 - <br />