Doris H. Blackman Weir 1951 <p> This report describes the geologic features that can be used to appraise the favorability of ground in guiding diamond-drill exploration for carnotite deposits in the Upper Jurassic Morrison formation on the Colorado Plateau. It is based on a statistical study of the geologic logs of about 2,500 holes drilled by the Geological Survey. The most useful features consist of the thickness of the ore-bearing sandstone, the color of the ore-bearing sandstone, the altered mudstone associated with the ore-bearing sandstone, and the abundance of carbonaceous material in the ore-bearing sandstone. Although each feature can be used alone to appraise the favorability of ground, an appraisal based on all of them together is even more useful. A method of expressing this favorability in numerical values is suggested.</p> <br/> <p>The results obtained by the Geological Survey using these geologic guides appear to be at least twice as favorable as the drilling results obtained with little or no geologic guidance.</p> application/pdf 10.3133/tei119 en U.S. Geological Survey Geologic guides to prospecting for carnotite deposits on the Colorado Plateau reports