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The eruptions of steam and gaseous matter which burst forth from the crater of Denise broke through laminated Tertiary clays, small pieces of which, some of them scarcely altered, others half converted into scoriae, were cast out in abundance, while other portions must have been in a state of argillaceous mud.
Under deep black mosses, through which no ray of light can penetrate, every condition for dissolving siliceous bodies should be found, according to the supposition in question; neither will sufficient time be found wanting, in those deep mosses, upon the summits of our mountains; yet, examine the matter of fact? not the smallest solution is to be perceived in the siliceous parts of the stones which are found under those mosses, but every particle of iron is dissolved, so that the surface of every stone is white, and nothing but the siliceous earth of the feld-spar, and perhaps the argillaceous, is left.
This stone is generally found among the bituminous schistus, or black argillaceous strata, either in separate masses of various shapes and sizes, or forming of itself strata which are more or less continuous in their direction among the schistous or argillaceous beds. This mineral contains, in general, from 40 to 50 per cent. of iron, and it loses near one third of its weight in calcination.
Our author, on the contrary, supposes these formed by a species of chemical transmutation of calcareous and argillaceous earths, which, if not altogether incomprehensible, is at least not in any degree, so far as I know, a thing to be understood. This is not the place where that subject of these particular rocks, which is extremely interesting, is to be examined.
The soil of that part of the country with which we are best acquainted, is of a red argillaceous nature, generally forming a stratum of nine or ten feet in thickness, lying over one of sandstone, in which are imbedded fragments of lava; the latter stratum, at Point William, appears to decline to the east, at an angle of ten or twelve degrees.
Sand is separated and sized by streams and currents; gravel is formed by the mutual attrition of stones agitated in water; and marly, or argillaceous strata, have been collected, by subsiding in water with which those earthy substances had been floated. Thus, so far as the earth is formed of these materials, that solid body would appear to have been the production of water, winds, and tides.
"In the valley, near Bohio." "What have you found there?" "Clay-slate, hornblende, emeralds." "In large quantities?" asked Chester, anxiously. "There is a fortune underground there," was the reply. "Green argillaceous rock means something."
In that case we can scarcely ever penetrate a stratified mass for a few hundred yards without beholding a succession of extremely dissimilar rocks, some of fine, others of coarse grain, some of mechanical, others of chemical origin; some calcareous, others argillaceous, and others siliceous.
From the shortness of our visit, I did not examine these beds with care; some of them, especially those of the white, yellow, and brown shades, originally existed as streams of lava, but the greater number were probably ejected in the form of scoriae and ashes: other beds of a purple tint, porphyritic with crystal- shaped patches of a white, soft substance, which are now unctuous, and yield, like wax, a polished streak to the nail, seem once to have existed as solid claystone-porphyries: the red argillaceous beds generally have a brecciated structure, and no doubt have been formed by the decomposition of scoriae.
Such differences in the fossils as distinguish the calcareous and argillaceous deposits from each other, would be described by naturalists as arising out of a difference in the STATIONS of species; but besides these, there are variations in the fossils of the higher, middle, and lower part of the oolitic series, which must be ascribed to that great law of change in organic life by which distinct assemblages of species have been adapted, at successive geological periods, to the varying conditions of the habitable surface.
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