Penny Blood: Serial Sensation and Working-Class Entertainment — page 277: what you’re looking at

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

260 DISTRIBUTION OF VOLCANOS. [cH. XXI. eocene volcanic bands are no doubt nearly related to the recent ones, but those of previous periods have probably little connec- tion with any now existing. The great volcanic bands of the present day have an obvious relation to the boundaries, which separate the oceans from the continents, They skirt the coast-lines, either upon the edge of a continent, as along Western America, or else they occupy chains of islands parallel to the continental shore, as is the case along the Eastern coast of Asia. Besides these coast-line vents, others are found in the open ocean. These also appear to hold still acertain relation, though an altogether different one, to the coast-lines. Their position is medial. Thus in the Atlantic they occupy a medial line, rudely parallel to the opposite coasts ; and in the Pacific, the boundary of which is somewhat circular, they are found in a central patch in the Hawaian group. It also appears that an important distinction may be drawn between the modes of occurrence of coast-line and of oceanic volcanos. The cones raised by the former in some instances, no doubt, emulate in height, if they do not overtop, the crests of the ranges upon which they are parasitic. But they can by no means be considered as constituting a largely integral part of any mountain chain. If then such a chain were to be sub- merged, until only the tops of the highest mountains were left uncovered, the resulting islands would not as a rule consist of volcanic products, but, on the otner hand, they would chiefly present crystalline or schistose rocks. Now the case is exactly the opposite with oceanic islands. They are all volcanic, Dar- win, in his work on “Coral Reefs,” tells us that “the geological nature of the islands which are encircled by barrier reefs varies; in most cases it 1s of ancient volcanic origin; owing apparently to the fact that islands of this nature are the most frequent within all great seas; some however, are of madreporitic lime- stone, and others of primary formations, of which latter kind New Caledonia offers the best example’.” So also are some of 1 “On the Structure and Distribution of Coral reefs.” Second Ed, 1874, p. 62. GONG oOo SS (CO)