This was the initial CGS statewide coal summary — providing information not otherwise available on the coal resources across the state. It was subsequently updated in 1975 by SP-09 and in 1979 by SP-13, after which more detailed analysis of historical data, geology of coal fields and regions, and the total coal resources of the state was provided in SP-23, SP-24, SP-36 and SP-41. 15 pages. Digital PDF download. SP-03D
From the Abstract
Colorado has approximately 10% of the total U.S. coal resources. These resources occur in eight coal regions and 20 coal fields that occupy about 28% of the total area of the state. Most of the coal is of Upper Cretaceous age but some is of much younger Paleocene and Eocene age. The higher rank coals are generally in older Upper Cretaceous strata of the San Juan region while the lower rank coals are in the youngest Upper Cretaceous and Tertiary rocks in the Denver Basin and Green River regions. The coals generally range in rank from high-volatile B bituminous to sub-bituminous and lignite, however igneous intrusions and structural deformation locally metamorphosed the coal to semi-anthracite and anthracite. About 77% of the coal in Colorado is bituminous, 23% sub-bituminous and less than 1% anthracite.
Total coal resources are conservatively estimated at 230,164 million tons to depths of 6,000 feet. Approximately 560 million tons of coal have been produced to date. As technology improves so that coals deeper than 3,000 feet can be utilized, and as drill and core data become available, estimates of total coal resources will probably increase substantially. The Uinta region has the largest coal resource followed in order by the Green River region, the Denver Basin region, the North Park region and the San Juan region.