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It would be very difficult to ascertain the relative superposition of these several masses, for we shall afterwards see in the Cumbre Pass that the gypseous and intercalated beds are lens-shaped, and that they thin out, even where very thick, and disappear in short horizontal distances: it is quite possible that the black shales and red sandstones may be contemporaneous, but it is more probable that the former compose the uppermost parts of the series.
Often the greater part of the mass of a range will consist of these "older" and harder rocks, which by the erosion of the soft underlying shales are left standing in picturesque, rectangular, cathedral-like masses, easily recognizable as far off as they can be seen.
Magnified 3 diameters. In the upper part of the Mountain Limestone group in the south-west of England, near Bristol, limestones having a distinct oolitic structure alternate with shales. In these rocks the nucleus of every minute spherule is seen, under the microscope, to consist of a small rhizopod or foraminifer. Classification of the Old Red Sandstone in Scotland and in Devonshire.
Cannel coal, Boghead or Bathgate coal, and bituminous shales of various qualities, have all been requisitioned for the production of oils, and from these various sources the crude naphthas, which bear a variety of names according to some peculiarity in their origin, or place of occurrence, are obtained.
MICA SCHIST, the most common of schists, and in fact of all metamorphic rocks, is composed of mica and quartz in alternating wavy folia. All gradations between it and phyllite may be traced, and in many cases we may prove it due to the metamorphism of slates and shales. It is widespread in New England and along the eastern side of the Appalachians.
For instance, I shouldn't care to live for ever with Widow Shales, the pale-faced tailoress, nor yet with her humpbacked son, whose hump was such a constant source of wistful wonder and solicitude to you as a child. She gave a merry little laugh of reminiscence.
We will take the sandstones and shales first. They are grains of sand known to mineralogists as quartz, and consisting of a substance called silica by chemists. The grains of sand are bound together by a cement which in some few cases is identical in composition with themselves, and consists of pure silica, but usually is a mixture of sandy, clayey, and other substances.
Others are argillaceous clays, shales, &c., chiefly derived, probably, from the slate beds of the primary series. Others are calcareous, derived from the early limestone. As a general feature, they are softer and less crystalline than the primary rocks, as if they had endured less of both heat and pressure than the senior formation.
Shales had made every effort to find her, but without avail, and was compelled at last, by the demands of his business, to give up the quest. He had returned on the previous evening, and my mother had enjoined him not to tell me what had been done, though she seemed much distressed at hearing that Winnie was lost, and was about to send others into Wales in order to find her, if possible.
The deeper the water in which it falls the greater the possibility of its drifting farther still, since in sinking, it would fall, not vertically, but rather as the drops of rain in a shower when being driven before a gale of wind. Thus we should notice that clays and shales would exhibit a regularity and uniformity of deposition over a wide area.