US GEOLOGICAL SURVEY 1999 RESOURCE ASSESSMENT OF SELECTED COAL ZONES IN THE NORTHERN ROCKY MOUNTAINS AND GREAT PLAINS REGION, WYOMING, MONTANA, AND NORTH DAKOTA

摘要

In 1999, 1,100 million short tons of coal werernproduced in the United States, 38 percent from thernNorthern Rocky Mountains and Great Plains region.rnThis coal has low ash content, and has sulfurrncontent in compliance with Clean Air Act standardsrn(U.S. Statutes at Large, 1990).rnThe National Coal Resource Assessment for thisrnregion includes geologic, stratigraphic, palynologic,rnand geochemical studies and resource calculationsrnfor 18 major coal zones in the Powder River,rnWilliston, Green River, Hanna, and Carbon Basins.rnCalculated resources are 660,000 million short tons.rnResults of the study are available in U.S. GeologicalrnSurvey Professional Paper 1625-A (Fort Union CoalrnAssessment Team, 1999) and Open-File Report 99-rn376 (Flores and others, 1999) in CD-ROM format.