166 GEOLOGY OF OH10. 
The diminished thickness of the coal in the Bridgeport and German 
Company’s mines may be due to another cause than that I have sug- 
gested, viz., a swell in the bottom of the marsh, where the coal accumu- 
lated as peat, and on which, being relatively high, the peat was thin. 
It is well known that the ‘“‘swamps,” or lowest portions of the coal mines, 
have the thickest coal in them, and this is simply because the peat was 
deepest there. On the ridges or swells of the bottom the coal is thin and 
high, because the top only of the peat bed reached over them. The bar- 
ren ridges which so often separate the coal “swamps” were islands in, or 
the shores of, the coal marshes. These rose above the water-level, and 
on their slopes the peat diminished in thickness upward till it came to 
an edge. When covered with clay and sand, and compressed to solid 
coal, that was thickest where the peat was thickest in the bottoms of the 
basins, and thinned out to nothing on the slopes which bounded these 
basins. 
The Massillon coal is usually overlain by a few feet of shale, and above 
this is found a massive sandstone, which I have called the Massillon 
sandstone. This is a marked feature in the geology of many of the 
counties which lie in the northern half of the Ohio coal field. It is well 
shown at the quarries of John Paul, at Fulton; at the Bridgeport quarry 
(John Vogt’s); and that of Warthorst & Co., at Massillon, where it at- 
tains a thickness of from sixty-five to seventy-five feet. The stone of this 
stratum varies considerably in texture in different localities and differ- 
ent layers, but much of it affords very excellent building material, as well 
as good grindstones. In these a large and active industry has been cre- 
ated about Massillon, Warthorst & Co. giving employment to one hundred 
men, and shipping three hundred to four hundred car loads of block stones 
and fifteen hundred to two thousand tons of grindstones perannum. The 
product of their quarry is mainly sold in Pittsburgh, Philadelphia, and 
Baltimore. The stones for dry grinding—plows, springs, etc.—are espe- 
cially esteemed. In Paul’s quarries, near Fulton, a light variety of this 
stone is ground up, and the sand is shipped to Pittsburgh for the manu- 
facture of glass. | 
In Mahoning, Portage, and Summit counties this rock affords a con- 
venient guide in the explorations for coal, as it lies above the lower and 
under the next two workable seams. It has alsoin many instances been 
instrumental in the destruction of much valuable coal territory, inas- 
much as the currents of water by which it was transported carried away 
the underlying coal, and now sandstone occupies its place. In the deep 
channels of these old currents this rock sometimes attains a thickness of 
nearly one hundred feet. | 
In many parts of Stark county borings have indicated the existence 
