The Lower Siluric Shales of the Mohawk Valley

The Lower Siluric Shales of the Mohawk Valley

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 edition. Excerpt: ...the Frankfort shale. Its most striking elements are the eurypterids and the seaweed Sphenophycus, but it also contains a number of species that indicate that it can not be younger than upper Trenton age and probably belongs mainly below the upper Trenton. Since these beds are connected by transitional beds with the underlying Canajoharie shale of lower and middle Trenton age, the inference of their middle and upper Trenton age is also supported by the stratigraphic relations. The formation is therefore here given a new name, the Schenectady formation. This formation attains a great thickness (approximately 2000 feet) in the lower Mohawk region, but does not extend far westward and ends abruptly eastward against the folded region. It is characterized by numerous intercalations of "bluestone," a calcareous sandstone, by mud-cracks, rapid horizontal alteration of sediments and other features which indicate nearness of the coast. This coast was probably to the east and the great thickness of the Schenectady beds in this region is due to their formation in a sinking trough parallel to and in front of the Green Mountain-Taconic fold system. The Schenectady beds strike for this reason from north-northeast to south-southwest. 5 The uppermost portion, about 300 feet, of the " Frankfort" beds at their eastern edge in Albany county has been found to contain an entirely different fauna and also to be lithologically somewhat different. This division has been termed here the Indian Ladder beds. These rapidly disappear westward, being absent at Cobleskill and probably formed originally a narrow belt extending north-northeast to south-southwest; they are hence for the greater part buried under Devonic rocks in the south, and lost by erosion...show more

Product details

  • Paperback | 48 pages
  • 189 x 246 x 3mm | 104g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 123665093X
  • 9781236650931