Penny Blood: Serial Sensation and Working-Class Entertainment — page 306: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

CH. Xx11.] SUMMARY. 289 from different reservoirs of molten rock: for according to our view this would be actually the case. Thus we find five classes of phenomena explicable on the theory of mountain roots : (1) The support of the mountains themselves, (2) Theapparently insufficient attraction of the Himalayas, (3) The slower increment of temperature beneath moun- tains, (4) The gradual elevation of a tract concurrently with its denudation, (5) The natural sequence of volcanic rocks. XXI. The geographical distribution of volcanos presents fewer difficulties upon the supposition of a thin crust and fluid substratum, than upon any other. Their linear arrangement points to their being situated along great systems of fissures ; and such systems of fissures are indicative of a thin crust. Fissures, which run for long distances in nearly straight courses, point, either, as already mentioned when discussing faults, to a movement perpendicular to the fissured surface, or else to a rending pressure within the fissure itself; while on the other hand fissures, which are caused by contraction in a direction parallel to the surface, would divide up an area into polygonal figures. The former arrangement of the fissures accords best with the distribution of volcanic ranges, and suggests a thin crust. We recognise two principal types of volcanic regions, coast- line, and oceanic. We believe the former to be connected with the agencies which have raised the continents which they skirt. Trains of vents are attached laterally to the great compressed and elevated ranges, and usually stand near the edge of a steep shore. The oceanic volcanos on the other hand appear un- connected with true elevatory action, for the oceanic islands consist almost all of them of volcanic rocks: whereas, if they were connected with areas of elevation, the peaks of schistose or other hard inclined strata could not well be absent. F, 19 COLA @ (CO) TOO!