Laserfiche WebLink
<br />. <br /> <br />to about 20 percent. On a dry ash-free basis, the heat value ranges <br />from 14,500 to 13,300 Btu/lb, but some bituminous coals range as low <br />as 11,440 Btu/lb.. The "as-received" values given in Table B.l are <br />somewhat lower. <br /> <br />(\) <br />.... <br />en <br />CO <br /> <br />There are now 55 mines in production in Coloado, with the majority <br />being underground. The underground mines tend to be small and have lower <br />production, while the fewer surface mines have grearer production; <br />Due to complex folding, faulting, intrusion of igneous materials, and <br />steeply dipping strata in some of the coal basins, only small areas <br />have sufficiently shallow overburden to warrant strip mining. It is <br />estimated that 95 percent of Colorado's remaining coal must be ~ined <br />underground. Many newer mines, however, are surface or strip mining <br />operations. There are currently (1978) 20 surface mines in production <br />in the state. <br /> <br />. <br /> <br />Three major coal-producing regions in the Colorado River drainage <br />contribute almost 90 percent of the coal production in the state. <br />These are the San Juan, the Uinta, and the Green River regions (study <br />subunits 140801A, 140500C, and 140500B). The San Juan region, con- <br />taining the oldest coals, represents 5.5 percent of the state's <br />production with 657,260 tons in 1977 (Colo. Div. of Mines, 1978). <br />SeaJIs in the San Juan coal area range from 2'8" to 6'7" thick <br />(Keystone, 1977). The Uinta region produced 19.7 percent of the <br />state's 1977 production, or 2,363,241 tons, from 4'6" to 18' thick. <br />This region includes the Book Cliffs Field which is continuous ~ith <br />the.same field in Utah. The Green River region is responsible for <br />61.5 percent of the state's coal production, with 7,416,188 tons from <br />seams ranging between 3'8" to 12'4" thick (Keystone, 1977). The <br />Wasatch Formation in this area ranges from 6 feet to 20 feet, <br />representing a tremendous resource in the Green River coal region. <br /> <br />New Mexico <br /> <br />-New Mexico has coal in t~o major areas, one of which ~s the San <br />Juan region in the northwestern part of the state, which falls within <br />the drainage of the Upper Colorado River Region. The San Juan Basin is <br />geologically considered to be a part of the Colorado Plateau physio- <br />graphic region. The San Juan Basin is an asymmetric geologic basin <br />with shallow dipping strata to the west and south, which facilitates <br />strip mining methods there. Steeply dipping strata on the north and <br />east sides limits strip mining in the northern part of the basin. <br /> <br />The coal fields of. the San Juan River Basin in New Mexico are a <br />continuation of the San Juan coal region in Colorado, where the strata <br />are Cretaceous and early Tertiary in age. The lenticular (lens-shaped) <br />quality of the seams is one characteristic which pervades the deposits <br />of northwestern New Mexico. Strip mining has been introduced recently <br />(1972) on a fairly large scale in San Juan and McKinley counties <br /> <br />. <br /> <br />B-8 <br />