Laserfiche WebLink
• -4- <br />From 6 to 14 feet of sandy clay colluvlal soils were encountered over- <br />lying bedrock In the exploratory holes drilled along the escarpment. In <br />soma exploratory holes, from 2} to 4 feet of clayey gravel colluvium was <br />encountered between the overlying sandy clay colluvium and the underlying <br />bedrock. The colluvlal soils along the escarpment were derived from the <br />erosion and redeposition of upslope terrace deposits and bedrock. <br />Bedrock at the site consists of brown claystone and dark gray <br />fossilifarous marine shales of the Cretaceous age Lewis Shale. The <br />bedrock is weakly cemented but well consolidated. Powdery, white gypsum <br />was observed on some of the shale partings and in most Joints of the <br />claystone. Structurally, the site Is on the southwestern limb of the <br />:q <br />• Hayden syncline near the axls'of the fold. Regional mapping indicates 7 <br />that the bedrock dip is about 5o toward the north. Shale partings ,~ <br />observed (n the core also indicate a low dip between 2° and 5°. , <br />SUBSOIL CONDITiONS ' <br />~ The subsoil conditlana were Investigated by initially drilling <br />seventeen test holes within the truck dump, crusher, stockpile, train <br />loadout and conveyor system at the locations shown on FIg. 2. Work <br />points and locations of these test holes were determined by others. Two <br />test bolas each were also drilled at the office and change house building <br />and haul road deep cut locations to provide add'Itional.subsoil informa- <br />lion within these areas. Minimum depth of drilling was determined based <br />on preliminary excavation depths and type of construction. Additional <br />• <br />i <br />:f <br />2 <br />