Evaluation of coal resources near Denver metropolitan area. Lithologic analysis of Laramie Formation coal and Denver Formation lignites of 10 holes. 42 pages. 9 figures. 4 tables. 1 plate (1:200,000). Digital PDF download. OF-80-09D (See also open-file report OF-80-01)
Excerpted from the Introduction:
The Colorado Geological Survey continued its exploratory coal drilling program in the Denver East 1/2° x 1° Quadrangle. The program was designed to evaluate the coal resources of the quadrangle, especially near the Denver Metropolitan Area. … The second phase of the drilling program was needed to fill gaps left from the first phase of the drilling program. As in the first phase, holes were drilled in the Antelope Flats – Deer Trail area which contains the Laramie Formation coals, and the Watkins-Lowry area which contains the Denver Formation lignites.
Ten holes were drilled and geophysically logged with a coal suite (single-point resistance, focused density, caliper, and natural gamma) logging tool. Hole number CGS-30c was twinned and cored at select depths and samples were sent to Commercial Testing and Engineering Co. for analysis.
Lithologies were compiled using cores, drill cuttings, and geophysical logs. Similarity of the rock types permit the omission of full descriptions. Many lithologies have been combined in the descriptions to accommodate the reduced scale of the logs presented in this report.