Laserfiche WebLink
<br />GEOLOGY <br />General Geology <br />The sands and gravels deposited in the floodplain of the <br />South Platte River are Quaternary in age. These aggregates <br />were deposited by the South Platte River and its tributaries. <br />The Post-Piney Cteek Alluvium forms a surface cover on the <br />Louviers ~{lluvium trhich overlies the sandstones and shales of <br />the Denver-Arapahoe Formation. Figure 2 is a geologic map of <br />the area, and Fioure 3 is a geologic cr•uss-section sltoa:ing tl~e <br />relationships of the units mapped. <br />Forntati ons <br />The oldest rock unit to be considered in the study area is <br />the Cretaceous Denver-Arapahoe Formation. This bedrock forma- <br />tion is composed of very Chin to thick bedded clayey, silty sand- <br />stone and sandy silts tone with interbedded carbonaceous silty <br />shales and claystone. The carbonaceous shale is light to inediuin <br />dark gray and locally contains plant fragments with a few poorly <br />preserved leaf imprints. ?Iris shale unit of the Denver-Arapahoe <br />Formation is the bedrock in -the study area (6). <br />The Louviers Alluvium lies unconforntably on the Denver-Arap- <br />ethoe Formation and is a t•:ell graded sand and gravel de{rosit. The <br />Louviers is composed of: 65;~ quartz, 15`~ feldspar, and 20% rock <br />' fragments. The rock fragments are made up of granite, argillite, <br />• eery t•reathered metamorphics, chert and claystone. The Louviers <br />is typically a •dalley-fill stream deposit. The material leas been <br />~ ~co Cm~u*aZui~.~ <br />• 77-Szc -~.~~, <br />