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THE JOURNAL OF GEOLOGY.

In 1864 James Hall and Sir William Logan[1] visited Mt. Washington and described it as probably synclinal in structure.

The only investigator, however, who has made a detailed study of the geological structure of the mountain is Professor J. D. Dana, whose papers on the subject have appeared mainly in the American Journal of Science. His first paper dealing with the structure of Mt. Washington[2] appeared in October, 1873. It contains a sketch-map with dip and strike observations. On page 38 he states:

"Mt. Washington is a synclinal with limestone below and slate above."

And on page 39:

"We thus find evidence of a very broad synclinal across the center of Mt. Washington. But just north, in Egremont, the structure is totally different: the ridges S and T[3] are the sources of very steep and comparatively narrow independent synclinals with the axial plane inclined westward.***The synclinals S and T become merged in one mass in Mt. Washington; and as the limestone does not appear at the summit, the intermediate anticlinal in the mountain was only an anticlinal of slate. In other words, the synclinal of limestone beneath the mass of the mountain was one great trough with breaks and incipient flexures; while to the north these incipient flexures become two defined synclinals, with the intermediate anticlinal—the synclinals being courses in the ridges S and T and the anticlinal that of the limestone outcropping between; and then, farther north, there was formed the Taconic synclinal T alone."

In the same year there appeared in the Proceedings of the American Association a paper entitled "The Slates of the Taconic Mountains of the age of the Hudson River or Cincinnati Group.[4] In this paper Professor Dana states that limestone dips west under slates along the east slope of Mt. Washington for four miles, "that is, the whole eastern front." He describes

  1. ↑ Paper read by T. Sterry Hunt before the Natural History Society of Montreal, October 24, 1864.Reviewed in the American Journal of Science, 2d ser., Vol. xl, p. 96 (1865).
  2. ↑ On the Quartzite, Limestone and Associated Rocks of the vicinity of Great Barrington, Berkshire county, Mass., J. D. Dana, American Journal of Science, 3d ser., vol. vi., p. 37.
  3. ↑ The ridge S is that of Mts. Darby, Sterling and Whitbeck, and the ridge T that of Mts. Prospect and Fray near the New York-Massachusetts state line. (Cf. map pl. i).
  4. ↑ J. D. Dana, Proc. A. A. A. S., 22d (Portland) meeting, 1873, pp. 27-29.
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