The Fuel Resources of Colorado. — Lakes. 7 
Stockbridge limestone. The Berkshire schists send out tongues 
into the Stockbridge limestone area. There are also re-entering 
angles of limestone in the schist area corresponding to anticlinals. 
There are isolated schist areas which are more or less open s^'n- 
clinals and isolated limestone areas which are compressed anticlinals 
forced up through the overljing schists or truncated b}' erosions. 
Their relations are repeated between the upper limestone (Bellows 
Pipe limestone) and the G-reylock schist. 
delations of Geology to Topogvaplvy. The physically and chem- 
ically more resistant schists form the more elevated portions and 
the steeper slopes, while the broad valleys and gentle undulations 
about the mountain generally correspond to limestone areas. The 
upper limestone and calcareous schist constitute the benches of 
agricultural land high up on the sides of the mountain and ' ' the 
notch " so early settled ; and to the presence of this rock also, 
together with a northerly pitch, is due the deep incision in the 
central crest between Saddle Ball and Round Rocks. The N.-S. 
part of the Hopper cut was occasioned by the trend and up- 
turned edges of the calcareous belt. A minor anticlinal occurs 
on the west side of this part of the Hopper. The deep E.-W. 
incisions on both sides of the mountain are the results of erosion 
crossing the strike, while the great spurs on the west side are 
portions of the original mass left by this erosion. The saddle be- 
tween Greylock summit and Saddle Ball is due to the central 
synclinal of the mass, and the saddle seen in the mass from Mt. 
Equinox on the X. N. W. is due to the great trough in the cen- 
tral synclinal. The center of this ti'ough is the deepest part of 
the entire synclinorium. 
Newport, R. /., April 22, 1891. 
THE FUEL RESOURCES OF COLORADO. 
Bv A. Lakes, Golden, Col. 
RECENT DEVELOPMENT OF THE COAL FIELDS. 
Up to the past five or six years the comparatively small areas 
of coal discovered and developed within the reach of railroads, 
were confined to the narrow eastern and northeastern border of our 
mountains, and were monopolized by two or three companies, or 
leagued with two or three railroads. The markets were local also. 
Now, far greater and more important fields, with larger seams and 
