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•-n•ri►. . .T:T.-‘11111IP • <br /> 1/.41.1,14) 2. 4 C•�� <br /> CJOHN D.:=1:n.0.514M0011 t JOHIi1* BOLD <br /> Dimon, <br /> COLORADO GEOLOGICAL SURVEY • <br /> DEPARTMENT OF NATURAL.RESOURCES <br /> 964 COLUMBINE BUILDING-1446 SHEIMM1AN STREET <br /> DENVER. COLORADO 40203 PHONE 002-2111 <br /> July 2, 1974 <br /> Mr. Don White <br /> City of Louisville <br /> 749 Main Street <br /> Louisville, Colorado 80027 <br /> Dear Mr. White, <br /> Regarding our conversation of July 1, I as writing to summaries our <br /> thoughts about Davidson Mesa and the Coal Creek valley between Superior <br /> and Louisville, in Boulder County. <br /> The gravels capping Davidson Mesa probably do not exceed 6 ft in thick- <br /> ness. These deposits, although they were maimed at 2 locales and used in <br /> the past for road maintenance, contain significant amounts of calcium <br /> carbonates (caliche), incompetent rock cleats (sandstone), and fines <br /> (silt and clay). These three aspects together seriously limit a gravel <br /> deposit's potential for use an aggregate. He do not believe that these <br /> gravels can be economically upgraded to construction-aggregate speci- <br /> fications, and so, need not be considered for mineral conservation unless <br /> a producer or firm expresses interest in their development. The deposit, <br /> at beat, appears suitable as a source of road dressing and fill material. <br /> The terrace and valley deposits along Coal Creek northeast of Superior <br /> reach 11 ft in thickness and are free of calcium carbonate development <br /> and incompetent or weak rock cleats. As stated in the asp note just <br /> below Marshall Lake, the deposits consist mostly of cleats of quartette, <br /> a very durable and desirable aggregate component. Although significant <br /> fines wort seen in places, the gravels have been mined at 5 sites. We <br /> know of one gravel producer in Denver who is interested in the future <br /> mining of these deposits. On the basis of our observations, we feel <br /> that these terrace deposits can be commercially extracted and should be <br /> considered for mineral conservation. The continuation of those deposits <br /> onto the Lafayette quadrangle was inadvertently labeled "Tl" and should <br /> be "T2" as it appears on Plate 2 of the report. <br /> I hope that this information Is sufficient for your needs. Please contact <br /> us if we can be of further assistance. Thank you. <br /> Sincerely, <br /> Stephen Schvochov <br /> SDS/tdh GE Q`iet(�t Engineering Geologist <br /> STORY OF THE PAST - . .KEY TO THE FUTURE <br />