Bulletin Volume a - 25

Bulletin Volume a - 25

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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: ...In secs. 20 and 21, T. 47, R. 5 W., Town of Eileen, Bayfield County, the valley of the South Fork of Fish Creek exposes about 1800 feet of sandstone in vertical beds. The bedding varies from heavy to shaley with a little clay shale as shown in plate VIII, p. 52. The colors range from brick red, or occasionally even deeper shades, to clear white and show much mottling and banding of red and white. Beds composed almost exclusively of magnetite are also seen. Some are as much as eighteen inches in thickness but have only a slight lateral extent. Ripple marks, cross-bedded and irregularly bedded or domed beds occur, as shown in Figs. 6 and 7. Pebbles are not very common. Microscopic examination (Plate X, B, p. 56) shows that only a third of the rock is quartz. Feldspars (mainly orthoclase with some microcline and plagioclase, more or less altered), magnetite, mica, iron oxides, and rarely altered ferromagnesian minerals make up the larger portion of the rock. The grains are decidedly angular. as is usual in all the sandstones of the region. Were it not for the structural relations, however (see-1 Irving, R. D., Geol. of Wis., 1873-9, vol. III, pp. 14, 202; CopperBearing Rocks, Mon. U. S. G. S., vol. V, p. 132. Irving states that 2000 feet of strata were then seen, but the writer was able to find but the one exposure, about three-eighths of a mile long. No map of the river is accurate. t section, p. 63. and structure sections on map) these rocks might be regarded as the lower part of the Orienta formation. On the west side of Clinton (locally known as Marble, or sometimes Graveyard) Point, are low ledges dipping at a moderate angle to the northwest, exposing some 1,300 feet of finegrained and somewhat shaley to heavily bedded sandstone (Plate IX, p....show more

Product details

  • Paperback | 40 pages
  • 189 x 246 x 2mm | 91g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236564456
  • 9781236564450