The American Geologist Volume 1-36

The American Geologist Volume 1-36

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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. 1905 edition. Excerpt: ...Pacific railroad expedition along the thirtv-fifth parallel, when he pronounced the now celebrated Tucumcari section in eastern New Mexico as of Triassic and Jurassic ages, there has been waged one of the bitterest and most useless controversies in the history of American geology. Marcou was well acquainted with Jurassic and Triassic sections of Europe and. as Louis Agassiz has well remarked, he could hardly be blamed for seeing Am. Jour. Scl., (1), vol. xxvll, p. 134, 1859. a close analogy in the New Mexican sequence. The full force of this position finds another instructive parallel in the so-called Permian question of central Kansas." Both of these controversies doubtlessly would have been avoided had all participants relied less on analogv and more upon the actual critical criteria which the formations themselves supply. Singularly enough, after all these years in which Marco:1 has stoutly maintained the correctness of his original position, the "Triassic" part of the Tucumcari section appears finally to be determined without much doubt as Triassic in age. It now becomes a question of more than passing interest to inquire anew regarding Marcou's Jurassic beds of the same locality. According to Marcou's Pyramid mountain section, which is near the Cerro Tucumcari, and'which is essentially the same, there were included in his so-called Jurassic sequence (a) about 225 feet of soft, shaly, light-colored sandstones, which Hill has since correlated with the Trinity sands of central Texas, (b) 50 feet of bluish fossiliferous shales, which Hill considers as forming the uppermost poriton of the Washita division of the Comanche series, and from which Marcou collected his few fossils, and (c) 50 feet of massive yellow calcareous...show more

Product details

  • Paperback | 218 pages
  • 189 x 246 x 12mm | 399g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236981723
  • 9781236981721