304 W. H. WEED — TWO MONTANA COAL FIELDS. 



The seam has been opened at several places, and desultory working for 

 the local supply has been attempted on St. Johns creek, west of the Mis- 

 souri, and on Bird creek, Hound creek, Smith river, Dry Arrow creek, Wil- 

 low creek, and Sage creek. The more extensive workings of Belt creek are 

 sufficient to prove the value of the seam ; the mines at Sandcoulee have 

 an average daily output of 1,300 tons. It will he seen from the localities 

 cited that the field embraces a strip of country a few miles in width, but 

 extending along the base of the mountains for 125 miles, its extreme 

 limits being yet undetermined (see figure 1). 



Configuration and Structure. 



Throughout its entire extent the coal field is an open, grassy plateau 

 or prairie country, but rarely presenting low buttes or eminences left 

 by the erosion of higher strata, and cut by numerous drainages whose 

 coulees show sections of the rocks. To the southward the Belt moun- 

 tains form a rugged range whose higher slopes are dark with a heavy 

 growth of pines, the lower slopes presenting that park-like character 

 that forms one of the chief charms of Rocky mountain scenery. The 

 plateaus of the coal field extend northward, forming the western limit of 

 the great plains. In the center of the field, Belt creek has cut a narrow 

 valley whose groves of cottonwood and alders are in pleasant contrast to 

 the monotonous grasslands of the plateaus. Belt butte, a conical hill of 

 horizontal shales and sandstones, forms a conspicuous landmark, the 

 girdle of sandrock about its slopes giving it the name. To the eastward 

 the Highwood mountains break the continuity of the plains, rising 

 abruptly as an isolated cluster of picturesque peaks. The drainage of 

 the coal field, at least that part of it winch was visited, i- peculiar: The 

 level plateaus are trenched by narrow coulees, which are frequently 

 partially tilled with drift and are now occupied by streams of relatively 

 small size, streams that even in flood are not proportionate to the valleys 

 they occupy. The evidence seems to show that a period of depression, 

 when the plateaus were cut, was followed by a short time of relatively 

 high elevation accompanying the advance of local glaciers and a vigorous 

 drainage, which was followed in turn by the present period of scanty 

 precipitation. 



The abundance of glacial drift on the plateaus was noted by Professor 

 Newberry. It is conspicuous when the glacial gravels till pre-existing 

 hollows and drainage channels, but on the mesas forms hut a thin and 

 widely spread mantle in which the bowlders are seldom of large size. 

 The material points to local origin of the drift, coming from the Little 

 Belt range. In the coal field proper no true moraines were observed. 



