Four holes were drilled in the Book Cliffs coal region of Garfield County, Colorado and Grand County, Utah to provide coal core samples suitable for analysis and stratigraphic information about coal-bearing strata. Three of the holes were completed; the fourth remains to be completed; a fifth is planned. A total of 1,693 feet (515 m) of pilot-hole rotary drilling and 843 feet (257 m) of core drilling was done. Mechanical and geophysical logs of the first, third, and fourth pilot holes were made; only the upper part of the second hole, which was almost entirely cored, was logged. Most of the cored rock is from the coal-bearing Neslen Formation and almost all of it is carbonaceous to some degree. Lithologies of the rotaried intervals are shown in the accompanying plate and were interpreted from geophysical logs and cuttings.
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Preliminary results of coal exploratory drilling in the Book Cliffs coal region, Garfield County, Colorado, and Grand County, Utah