Contributions from the Geological Department of Columbia University Volume 21

Contributions from the Geological Department of Columbia University Volume 21

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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. 1912 edition. Excerpt: ... greatly to be regretted that Professor Williams's untimely death prevented the further prosecution of his work in the district; a complete study of the magmatic differentiation in the Cortlandt Series would have been indeed valuable from a petrologist of his experience and perspicacity. Consonant with his original plan, having completed his study of the igneous rocks themselves, he describes their effect on the surrounding " "Original Gnelssold Structure In the Cortlandt Series," Amer. Jour. Sci., (4), XXXI, 125. 1911. "Op. 00., p. 243. ""Gabbros and Dlorltes of the Cortland! Series," Amer. Jour. Sci., (3), KXXV. 438. 1883. O rocks." He here states that the emery may be referred with certainty to contact action on pre-existent material, apparently abandoning his former view. In studying the other contact effects, he concentrated on several linear sections, in the first two of which he describes the succession from ordinary mica schist to the same rock carrying sillimanite, then to a rock composed of sillimanite, mica and garnet, and finally to a garnetiferous mica diorite. Analyses show that the change in the schist is in the direction of an increased alumina and iron content as the massive rocks are approached. In the last section of the massive rocks on the limestone, he finds that lime-bearing hornblende and pyroxene are formed along the contact. He finally compares the effects here with those in several European localities, showing that a larger number of contact minerals is found in the Cortlandt than anywhere else. The contact effects were thus shown to be well developed, a point which will be reverted to in the discussion of the genesis of the emery. James F. Kemp," in 1888, ...
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Product details

  • Paperback | 252 pages
  • 189 x 246 x 13mm | 458g
  • United States
  • English
  • black & white illustrations
  • 1236751353
  • 9781236751355