Laserfiche WebLink
• <br />• <br />• <br />Alluvial fan d_eposi_ts consist of stream deposited mater- <br />ial, mostly derived from the Mancos Shale. The deposits are <br />fine-grained; clayey sand and silt with gravel. The coarser <br />material often forms lenses. Only one feature of this type <br />was defined in the study area. Other smaller and less distinct <br />fans may exist in conjunction with the pediment deposits or <br />colluvial soils. <br />Old-(PleistoceneZ_River_Terraces,consist of river deposit- <br />ed gravels; poorly sorted, sub-angular gravel, cobbles and <br />boulders in afine-grained matrix. Larger material may occur <br />in lenses. <br />Freguent_outcrops_of_the Mesaverde Formation were mapped <br />---------------------- <br />in a limited area of Stevens Gulch. Much of the formation is <br />covered by surface deposits. The Mesaverde Formation consists <br />of light-colored sandstones interbedded with dark shales. The <br />highly resistant sandstones form cliffs and ledges which are <br />clearly visible on the valley walls. Rollins Sandstone at the <br />base of the Mesaverde is a typical example of such ledge. The <br />shales tend to weather easily and form reduced slopes in out- <br />crop. Consequently, large areas of Mesaverde outcrop often <br />have a stepped appearance. <br />Frequent outcrops of the Mancos Shale were mapped where <br />------------------------------------- <br />the formation was not obscured by surface deposits. The P1an- <br />cos Shale consists of a thick sequence of marine-deposited, <br />silty shales. The formation tends to form rolling, deeply <br />incised topography, but may form relatively steep slopes where <br />capped by erosion resistant sandstone or terrace deposits. <br />A-4 <br />6eoa+wrto cor+w~nr~c, wc. <br />