The Sciences, Or, Chemistry, Mineralogy, and Geology Illustrated; With an Atlas of Twenty-Four Steel Plates, Containing One Thousand Illustrations. Atlas

The Sciences, Or, Chemistry, Mineralogy, and Geology Illustrated; With an Atlas of Twenty-Four Steel Plates, Containing One Thousand Illustrations. Atlas

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1856 edition. Excerpt: ...however, illustrate the peculiar relations existing between external form and the kind of rock. The generalization has been made, that the same rock species, when in not too inconsiderable quantity, has constant external features, so that a practised eye may, in many cases, draw an accurate inference as to the character of a mountain from a far distant view of it. Thus granite generally assumes the form of a spherical segment, trachyte that of the bell, while volcanic masses occur in the shape of a cone. The differences which exist amongst mountain ridges may have reference either to the ridge itself, or to the vertical cross-section. In the first point of view we distinguish between straight and curved ridges; in the second, between a circular, a parabolic, and a roof-shaped cross-section. In considering the slope of a mountain the geognosist first investigates the angle which it forms with the horizon. This angle, capable of infinite variation, is exceedingly diflicult to ascertain, even approximately, without instruments, its determination being very much exposed to optical illusions. It becomes necessary to set artificial boundaries between the most frequent angular differences, and to express them by artificial appellations. i ' There may be modifications in respect to the continuity of the declivity, which contribute in great measure to the character of the mountain. This may either be uniform and uninterrupted, or may have a stairway or terrace IOONOGRAPHIO ENCYOI.0PdiDIA.---VOL. 1. 35 545 form: it may be cut up by furrows or intersected by ravines. The foot of the mountain, which in its slope and expansion may exhibit considerable diversity, experiences on the whole the same variations in the angle of inclination as the descent;...show more

Product details

  • Paperback | 124 pages
  • 189 x 246 x 7mm | 236g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236959132
  • 9781236959133