318 JESSE E. HYDE 
for the moment, if present generally, is seldom observed; the sand- 
stone does not tend to form cliffs, and outcrops of this horizon are 
scarce. 
The base of the sandstone which rests sharply either on the coal 
or on the shale when the coal is absent, rises and falls irregularly 
through several feet, and suggests strongly the existence of an 
erosion surface. This suggestion is supported especially by the 
distribution of the coal which is present only where the base of the 
sandstone is high, and disappears where it is low. It is not unusual 
to find coal seams overlain by a sandstone, which are thinner or 
wanting. entirely in places because, as commonly expressed, the 
sandstone “‘cuts out’ the coal. It has generally been supposed 
that such an interruption is due to erosion, and doubtless it is in 
some cases; but in the present one, this is not the correct explana- 
tion. At only one point, and that for but a few feet, is there any 
evidence of erosion, and even that is not conclusive in view of the 
irregularity found at all other points. 
OCCURRENCE OF THE COAL IN POCKETS NOT DUE TO SUBSEQUENT 
EROSION BUT AN ORIGINAL CHARACTER 
There are some ro or 12 shale crests in the 300 yards which are 
clearly exposed, each with a bed of coal on the crest. In the sand- 
stone-filled ‘‘troughs” which intervene there is no coal. The 
thickness of the coal, where present, varies from a fraction of an 
inch to 35 inches, rarely exceeding a foot. Horizontally, the coal 
may persist for only 2 or 3 feet on a small crest, or it may persist for 
40 or 50 feet over a larger one. The sandstone troughs are of about 
equal width. But the coal is not truncated by the sandstone as it 
descends on either side of the crest.. The coal seam splits and dis- 
appears on either side by interfingering with those portions of the 
sandstones which fill the “‘troughs.’”’ The seam may split abruptly 
into two or three thin streaks, and each of these in turn into as 
many or more within a few inches. Not infrequently two partings 
will reunite around a thick lens of sandstone. 
There appears to be only one possible interpretation of the 
relation of the coal to the sandstone. The vegetable matter was 
accumulated in very limited patches, and coarse sands, sometimes 
