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STRUCTURE OF THE MOUNT WASHINGTON MASS.
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relations in the vicinity of the mountain are set forth on Plate III.

Horizons Represented.—The Mt. Washington series thus consists, not of two members as supposed by Dana, but of four, two of which are calcareous. The calcareous beds alternate with the schists, which have been shown to possess marked lithological differences. The sequence of these beds is as follows: (a) a calcareous horizon which I designate the Canaan Dolomite from its typical development at Canaan; (b) the lower schist bed, which I call the Riga Schist from Mt. Riga peak where it is perhaps most typically developed; (c) a calcareous horizon, which I designate the Egremont Limestone from its wide extent in the Egremont valley (this limestone is much modified in all localities above the valley floor); and (d) the upper schist horizon, to which I give the name Everett Schist since it assumes its maximum thickness within the area at Mt. Everett. It will be noticed that this sequence corresponds with that which Dale has determined for the Greylock mass in northern Berkshire county.[1] Below are given in parallel columns for comparison the series of Mt. Washington and Greylock:

Mt. Washington Series.

  1. Canaan Dolomite.
  2. Riga Schist.
  3. Egremont Limestone.
  4. Everett Schist.

Greylock Series (Dale).

  1. Stockbridge Limestone.
  2. Berkshire Schist.
  3. Bellows Pipe Limestone.
  4. Greylock Schist.





These beds are probably Ordovician though the lower portion of the Canaan Dolomite may, like the Stockbridge Limestone, be Cambrian.[2] No fossils have as yet been found in the vicinity and it is hoped that further search may reveal them. Walcott[3] has

  1. ↑ The Greylock Synclinorium, by T. Nelson Dale. Amer. Geologist, July, 1891, pp. 1-7.Also given in detail in a forthcoming monograph of the U. S. Geological Survey, by Professor Raphael Pumpelly.
  2. ↑ On the Lower Cambrian Age of the Stockbridge Limestone, by J. Eliot Wolff, Bull. Geol. Soc. Am., vol. ii. 1891.See also Dale, ibid., vol. iii, pp. 514-519.
  3. ↑ The Taconic System of Emmons, and the use of the Name Taconic in Geological Nomenclature, by Chas. D. Walcott, Am. Jour. Sci., vol. xxxv, pp. 237-242, 399-401, March and May, 1888. (With map).
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