Geological Survey Professional Paper Volume A A 292-293

Geological Survey Professional Paper Volume A A 292-293

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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. 1987* edition. Excerpt: ...of the section. The remainder is made up of thin beds of claystone which commonly underlie the coal beds. The upper member of the coal-bearing formation consists of medium-grained buff-colored pebbly sandstone in layers 30-100 feet thick, separated by zones of clay 10-50 feet thick that contain thin woody coal beds. It is i00 feet thick at Suntrana, but it thins abruptly westward, and is probably only about 400 feet thick at Healy, where it crosses the railroad. At the top is a persistent bed of greenish-gray shale and claystone about 50 feet thick. The rocks of the coal-bearing formation are in general uncemented and poorly consolidated. They can be excavated easily with a pick or knife and can be scratched by a fingernaii. Frequent freezing and thawing have caused them to disintegrate rapidly to their constituent particles, which can be transported easily by the smallest streams. Consequently, gullies, badlands, and landslides are common on exposures in this formation. Because of the ease with which the rocks are eroded, the areas underlain by this formation are marked by broad plains, wide stream valleys, and low passes. The band of coal-bearing rocks that crosses the railroad at Healy is on the south limb of a large syncline, whose axis lies about 2 miles north of Healy. The formation in this band strikes about X. (10o K. and dips about 60o N. at Healy. Eastward, toward Suntrai.a. the formation strikes more to the east, and its dip decreases to about 35o N. The broad terrace south of Healy Creek and between Moody Creek and the Nenana River is underlain by the lower memtar of the coalbearing formation. Here the lower member is apparently in a syncline, for the white basal sandstone and conglomerate of the member crop out at many places around...
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Product details

  • Paperback | 148 pages
  • 189 x 246 x 8mm | 277g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236613651
  • 9781236613653