10 
DESCRIPTION OF THE ROCKS 
mixtures, having been long deposited and consolidated, extensive sub- 
terranean movements, connected with others probably of the same date 
in Scotland, Wales, and Ireland, happened beneath this district, and 
produced the general effect of throwing the strata on edge, in directions 
N. E, and S. W., and dipping S. E. Thus an irregular island appears 
to have been formed in the ancient ocean ; and, at the same period, the 
Grampians, the Lammermuirs, the northern slaty and schistose tracts 
in Ireland and Wales, and the Ocrynian chain of Cornwall, stood 
above the waters. The proof of this is more satisfactory in the case 
of the Cumbrian and Scottish mountains, than in the other instances, 
because the newer deposits of the carboniferous system encircle or 
border on both flanks their slaty ranges, but never ascend far into 
the interior; and in the country of the English lakes we see plainly, 
from the manner in which the mountain limestone mantles round the 
edges and ends of the slaty ranges, the general direction of the shore 
of the ancient sea. If any proof were wanting to add certainty to 
the conclusion that not only the slaty rocks had been displaced before 
the deposition of the carboniferous system, but in part elevated above 
the action of the sea, it is found in the character and situation of the 
lowest member of the carboniferous system, and in the nature of the 
vegetable remains which especially belong to that system. For the 
lowest rocks referred to are conglomerates of such extent, and so situated, 
as to be referrible only to floods acting on the slaty rocks, and the 
plants grew on dry land. 
The carboniferous system of strata derives its name from the most 
characteristic of its products, coal, which in different countries lies 
in different parts of the series. Not that every part of this series 
is productive of that valuable substance, but, in agreement with the 
well understood principle of geological classification, all the members 
of it are so related as to constitute (in England) one natural familv 
of rocks, which is named from the most important of its members. 
The classification of this system, most suited to the North of Eng- 
land, is contained in the following table which likewise expresses 
