350 W. H. WEED — COAL FIELDS OF MONTANA. 



Paleozoic rocks, which rest at steep angles against a core of metaraorphic 

 gneisses and granites. At the base of the mountains are the seams of coal 

 which form the chief source from which Montana's great mining and smelt- 

 ing industries must derive their supply of fuel. Unlike the lignites of the 

 plains, these are true bituminous coals of excellent quality, and vary from 

 dry steam coals to excellent coking varieties. These bituminous coals are 

 all older than the lignites, and belong to two geological horizons : Those of 

 Sand coulee, Deep creek and other localities in the vicinity of Great Falls? 

 on the Missouri, have recently been determined by Professor J. S. Newberry 

 to be of Kootanie age. In Montana the Kootanie rocks have not been 

 found on the eastern slopes of the Rockies, save in the vicinity of Great Falls 

 and in the Judith basin. Over half the entire coal product of the state is 

 obtained from strata of later age, which are found in the two fields forming 

 the subject of this paper. 



The relative amounts of coal mined in the state in 1889, from the three 

 geological horizons, were as follows : 



Lignite 5,263 tons. 



Later Cretaceous . . . . 191,138 " 

 Kootanie 166,480 " 



These amounts will be exceeded during the present year (1890), but the 

 figures will show quite as small a percentage of lignite mined, despite the 

 wide range of this variety of coal throughout the state. So far as known, 

 the bituminous coals are limited in their occurrence to the eastern and 

 mountainous regions of the state. 



Aside from the Kootanie coals of Great Falls, bituminous coals are known 

 to occur only in the following fields : Li the Upper Gallatin basin; near 

 Virginia City; in the Cinnabar field on the Upper Yellowstone; in the so- 

 called Bozeman coal field, and in its continuation eastward, the Rocky fork 

 field. 



The Cinnabar field was studied in some detail last summer, in connection 

 with a geological examination of the region for the United States Geological 

 Survey, in continuation of the geological survey of the Yellowstone National 

 Park under Mr. Arnold Hague, and the identity of its coal-measures with 

 those of the Bozeman field was established. The coal-bearing strata of the 

 latter field were traced for a distance of about 100 miles. 



The Cinnabar Coal Field. 



Location. — The small field known by this name is inmiediately north of 

 the Yellowstone National Park, on the banks of the Yellowstone river. 

 After leaving the deep canons of the Yellowstone National Park, the Yel- 



