. The story of the earth and man [microform]. Geology; Paleontology; Man; Géologie; Paléontologie; Homme. THE DEVONIAN AGE. 83 them of most remarkable organization. On the ma'gins of these waters stretched vast swamps, covered with a rank vegetation. But the period one of powerful igneous .activity. Volcanoes poured out their molten rocks over sea and land, and injected huge dykes of trap into the newly-formed beds. The land was shaken with earthquake throes, and was subject to many upheavals and subsidences. Violent waves desolated the coasts, throwing sand and gravel over the flats, and
. The story of the earth and man [microform]. Geology; Paleontology; Man; Géologie; Paléontologie; Homme. THE DEVONIAN AGE. 83 them of most remarkable organization. On the ma'gins of these waters stretched vast swamps, covered with a rank vegetation. But the period one of powerful igneous .activity. Volcanoes poured out their molten rocks over sea and land, and injected huge dykes of trap into the newly-formed beds. The land was shaken with earthquake throes, and was subject to many upheavals and subsidences. Violent waves desolated the coasts, throwing sand and gravel over the flats, and teariog up newly-deposited beds; and poisonous exhalations, or sudden changes of level, often proved fatal to immense shoals of tishes. Tliis was the time of the Lower Devonian, and it is marked, both in the old world a,nd the new, by extensive deposits of sandstones and conglomerates. But the changes going on at the surface were only symptomatic of those occurring beneath. The im- mense accumulations of Silurian sediment had by this time so overweighted certain portions of the crust, that great quantities of aqueous sediment had been pressed downward into the heated bowels of the earth, and were undergoing, under an enormous weight of superincumbent material, a process of bak- ing and semi-fusion. This process was of course ex- tremely active along the margins of the old Silurian plateaus, and led to great elevation of land, while in the more central parts of the plateaus the oceanic con- 'litions still continued; and in the Middle Devonian, in America at least, one of the most remarkable and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Dawson, J. W. (John William), Sir, 1820-1899. Toronto : Copp Clark
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