370 The American Geologist. December, 1903. 
coal is found in and around the mountains where there has 
been a crumpling and changing of the strata. Other portions 
of the Cretaceous in the state yield a poor variety of semi- 
bituminous coal and lignite. 
The best coal fields are found in the central part of the 
state, with Cretaceous lignite east and Neocene lignite west. 
It has been estimated that there are 13,000 or more square 
miles of Cretaceous bituminous and semi-bituminous coal area 
in Montana and about 25,000 square miles of lignite area. 
This docs not mean that all of this area is underlain by coal or 
lignite deposits, but that the deposits are found quite abundant 
throughout this amount of territory. 
The bituminous area in Montana is greater than the com- 
bined bituminous areas of North Dakota, South Dakota, Wy- 
oming, Washington, Oregon, Idaho, and New Mexico. The 
lignite area is next to that of North Dakota, which has a larger 
lignite area than any of the northwest states. 
The Montana bituminous coals, compare in efficiency, quite 
favorably, with the bituminous 'coals from the central and east- 
ern states. According to Mr. Storrs, Mr. Frank A. Wilder and 
others, the relative efficiency of the Montana coals compares 
with the relative efficiency of the Pennsylvania coals as follows : 
The relative efficiency of the Pennsylvania bituminous coal is 
taken as 100. The Livingston-Bozeman coals, which are bi- 
tuminous, have a relative efficiency of about 85. The Rocky 
Fork coal, a semi-bituminous variety, has a relative efficiency of 
nearly 95. The Clarke's Fork coal, which is also semi-bitumin- 
ous, has a relative efficiency of a fraction over jR. While the 
Miles City lignite has a relative efficiency of 60.5. These are 
from stationary boiler tests ; the tests from the locomotives are 
somewhat lower for all except the lignite variety, which was 
higher from 10 to 12 per cent. 
The above tests show the Montana bituminous coals to be 
but little inferior to Pennsylvania bituminous coals. The area 
of the Montana bituminous coal fields is several times greater 
than that of the Pennsylvania bituminous coal fields. Besides 
there are several good iron ore deposits found in Montana, 
some of which are near the coal deposits. 
The lignite deposits, as before stated, are found through- 
out the eastern and western thirds of the state, and the best 
