558 
this pomt a mass of anthracite forty feet thick, deducting three in- 
tercalated fire-clays and a fine thin vein of impure coal, is quarried 
in open day, a covering of forty feet of sandstone being entirely re- 
moved. In the south mine, where there is a sharp anticlinal fold in 
the coal, the Stigmaria-clay, four feet thick, was well seen, with 
nearly forty feet of coal above it and four below. In the Great mine 
Mr. Lyell observed the following section :— 
Top, yellow quartzose grit. 
Coal, two or three inches of the uppermost part of the 
bed being in the state of dust, as if they had been 
crushed or rubbed by the yellow quartzose grit...... 5 feet. 
Ble firesclayy, wath: tle Marice ae ees) scam asm eden 15 inches. 
Coal, including two or three seams of an impure slaty 
DIESE TERE Ge cer ey ge ee eee eee a tte Hee hint 25 feet. 
Blue fire-clay with Stigmariz............... Silda 2 feet. 
Coal, with an intervening layer of hard, bituminous slate 8 feet. . 
The anthracite, as in other parts of these coal-measures, often 
exhibits a texture exactly like that of charcoal; and frequently im- 
pressions of striated leaves, exactly resembling, as pointed out by 
Prof. Rogers, those of liliaceous plants, particularly the iris. 
Mr. Lyell, accompanied by Prof. Rogers, afterwards examined the 
Room Run mines, on the Nesquahoning, where he saw a splendid 
exhibition of Stigmariz in a bottom clay, one stem, about three 
inches in diameter, being no less than thirty-five feet m length. In 
the roof of slaty sandstone were impressions of Pecopteris, Glos- 
sopteris, and other ferns. 
At Beaver Meadow, or the middle coal-field, a bed of anthracite is 
overlaid as well as underlaid by Stigmaria blue clay ; the upper fire- 
clay, however, soon thins out, and is replaced by sandstone. No coal 
rested upon it, but Mr. Lyell observes that the carpeting of coal 
may not be always large enough to cover the flooring of fire-clay, or 
some change of circumstances or denudation may have interfered 
with the usual mode of deposition. Upon the whole, Mr. Lyell 
says, the accumulation of mud and Stigmariz was, in Pennsyl- 
vania as in South Wales, the invariable forerunner of the circum- 
stances attending the production of the coal-seams. The two ex- 
treme points at which he observed the Stigmaria-clay, Blossberg and 
Pottsville, are about 120 miles apart in a straight line, and the ana- 
logy of all the phenomena at those places, and still more on both 
sides of the Atlantic, is, he says, truly astonishing. In conclusion, 
Mr. Lyell states, that he had just received a letter from Mr. Logan, 
announcing the existence of the bottom clay, with Stigmariz, in 
Nova Scotia; and that Mr. Logan had visited Mauch Chunk. 
