GEOGNOSY AND GEOLOGY. 155 
disturbance of the strata. The amount of coal is very small in proportion 
to the extent of the basin. It is only in two places, to the north on the 
Glan and to the south near Saarbriick, that the yield repays the expense of 
mining. The most important bed is about thirteen feet thick. The English 
coal formation is more extended, and by the abundance of coal exercises a 
great influence upon the production of iron. Much of the English iron is 
derived from spherosiderite (carbonate of iron), which occurs in large 
quantities in the carboniferous system, and even in the coal measures 
themselves, so that the same mine may furnish both ore and fuel. It is to 
this, above all, that the cheapness of the English iron is owing. Pl. 46, fig. 7, 
represents the succession of strata in the English coal formation. It there 
rests immediately on the Devonian, a, against which leans the mountain 
limestone, b; next come the strata of the millstone grit, c, which are 
covered by the lower coal beds, d, containing a large amount of iron-stone ; 
next by the main coal, e, and the upper coal, f, combined with the fresh 
water limestone. The latter concludes the series, which is succeeded 
immediately by members of the Permian and new red sandstone. 
No country possesses a larger amount of coal] than North America, and 
in none is it found more extensively distributed. It occurs in Nova Scotia, 
New Brunswick, Massachusetts, Connecticut, Rhode Island, Pennsylvania 
on both sides of the Alleghanies, Virginia, Maryland, Ohio, and several 
others of the Western States. Among the most remarkable of these 
localities are the anthracite beds of eastern Pennsylvania. They are not 
constituted of the mineralogical species anthracite, but of a variety of 
common coal containing very little bitumen, and burning with little smoke 
and flame. This variety occurs in three basins: the Wyoming, the 
Schuylkill, and the Lehigh. The former is nearly seventy miles long and 
about five broad, occupying part of the valley of the Susquehanna river. 
Fosstis or THE Carsonirerous Pertop. As already mentioned, 
vegetable remains are most conspicuous in the coal strata, particularly 
the vascular cryptogamia, such as Equisetacee, Filices, and Lycopo- 
diacee, of sizes far exceeding those attained by modern members of 
the same families. Among the Equisetacee belong the Calamites, 
with straight cylindrical branches and high jointed stems. They are 
striated longitudinally, some with a sheath going round the stem, as in 
the common Equisetum or horsetail, and others without it. The largest 
known remains must have belonged to individuals more than a foot in 
diameter. Such, for example, is Calamites approximatus. These gigantic 
forms sufficiently indicate that certain agencies were at work in the earlier 
periods of the earth’s history, which favored the development of vegetation 
to an enormous degree. 
The different parts of many species of Filicoid plants, as ferns, &c., 
occur in great quantity: entire stems and leaves of arborescent ferns are 
found, and it is probable that the great mass of coal has been produced by 
accumulations of such ferns. Ferns have cylindrical stems, inclosed by 
circlets of leaves. When these fall off they leave scars behind them, of a 
lenticular shape, and higher than broad; when the leaves are extended 
585 
