1 2 ^ The Mine. 



by most geologists. In the mechanical aggregates, which abound so 

 much in this region, the parts are of every size, from that of large 

 pebbles to that of sand. The pebbles are chiefly quartz, and even 

 in the firmest rocks they are usually rounded and exhibit every ap- 

 pearance of having been vsrorn by attrition. The cement appears to 

 be a siliceous substance, and the masses are frequently possessed of 

 great firmness.* Beneath this rock, there is usually some variety of 

 argillaceous slate, which commonly, although not universally, forms 

 the roof of the coal: sometimes the sandstone is directly in contact 

 with the coal, the slate being omitted ; the slate also forms the floor. 



THE MINE. 



The mine at Mauch Chunk occupies an area of more than eight 

 acres, and the excavation is in platforms or escarpments, of which 

 there are in most places two or three. The coal is fairly laid open 

 to view and lies in stupendous masses, which are worked, under the 

 open air, exactly as in a stone quarry. The excavation being in an 

 angular area and entered at different points by roads cut through the 

 coal, in some places quite down to the lowest level, it has much the 

 appearance of a vast fort, of which the central area is the parade 

 ground and the upper escarpment is the platform for the cannon. 

 The greatest ascertained thickness of the coal is stated at about fifty 

 four feet; in one place it is supposed to be one hundred feet thick; 

 but that which is fully in view is generally from twelve to twenty or 

 or twenty five, and even sometimes thirty five feet. Several banks 

 of these dimensions are exposed, interrupted only by thin seams of 

 slate running parallel with the strata. The latter are inclined gener- 

 ally at angles from five to fifteen degrees, and they follow, with very 

 great regularity, the external form of the mountain. In some places, 

 they are saddle- or mantle-shaped ; in some positions they and the 

 attendant strata are wonderfully contorted, twisted and broken, and 

 in one place, both are in a vertical position, while at a litde distance 

 they return to the general arrangement. It is impossible to avoid the 

 impression that some great force has disturbed the original arrange- 

 ment and either elevated or depressed some of the strata. 



The various entrances to the mine are numbered. At No. 3 there 

 is a perpendicular section through all the strata down to the floor of 



* Exceedingly resembling the millstone grit, and sandstones of the English coal 

 measures; on comparing the specimens from Perm, with those in a collection recent- 

 ly received from Mr. Bakcwell, (author of the geology) I can mark no important 

 difference. 



