Laserfiche WebLink
<br />-12- <br /> <br /> <br /> <br />Geologists have separated the Valley sediments into two <br />formational designations: (1) The Alamosa formation, compos- <br />ing the top approximately 2,000 feet of unconsolidated gravel, <br />sand, silt and clay and volcanic deposits, and (2) the Santa <br />Fe formation, composed of similar but more consolidated sedi- <br />ments and volcanics, lying beneath the Alamosa formation. <br />Although the foregoing discussion of the full depth of <br />sediments is essential for an overall understanding of the <br />Valley and the Closed Basin area ground water picture, it <br />is only the very top of the Alamosa formation that is cur- <br />rently of primary concern to the Closed Basin Project. The <br />proposed project wells will extend from 60 to 100 feet in <br />depth and will penetrate, draw water from, and lower the <br />water table in a relatively shallow zone of water-bearing <br />sand and gravel layers. These shallow layers are considered <br />by the U.S.B.R. and U.S.G.S. to be separated from the main <br />body of artesian aquifers below them by a laterally extensive <br />layer or zone of essentially impervious clay and silt. The <br />impervious zone is referred to in the project report as the <br />first confining layer. The pervious water-bearing material <br />above the first confining layer has an average thickness of <br />about 60 feet but ranges from 20 to 120 feet. The San Luis <br />valley Closed Basin project deals with the salvage of water <br />from this upper pervious layer. <br />An inference which has arisen in most people's minds <br />concerning the Closed Basin is that it is Closed both in <br />C'uu396 <br />