Page:The Journal of geology (IA journalofgeology11893univers).pdf/297

In Professor Dana's last series of papers^[1] on the Taconic Area, he adds some strike and dip observations and prints a more complete map of the area. In the second of the papers,^[2] on pages 439-442, he describes the variations in character of the schist of Mt. Washington as showing a more intense degree of metamorphism in the eastern portions, and in conclusion states (p. 441): "The facts here reviewed relate, it should be remembered, to a single stratum, that overlying the limestone."

The several extracts above given will, I think, sufficiently explain Professor Dana's views regarding the structure of Mt. Washington.

On the geological map of the Taconic area compiled by Mr. C. D. Walcott,^[3] the Mt. Washington mass is indicated having the same relations to the rocks of the adjoining areas as is shown on Prof. Dana's map.

Conditions and Progress of the Present Investigation.—The writer made a partial reconnaissance of Mt. Washington in the season of 1889, but the mapping was largely done during the months of July and August, 1891. He was assisted during the season of 1891 by Mr. Louis Kahlenberg, at present instructor in chemistry in the University of Wisconsin. Mr. Kahlenberg has traced the contact of schist and limestone along the west base of the mountain. The work has been in charge of Professor Raphael Pumpelly, then chief of the Archean Division of the U. S. Geological Survey.

The reconnaissance of 1889 was made on the southeastern flank of the mass and furnished only equivocal evidence concerning the relations of the "Stockbridge" limestone of the valley to the schist of the adjacent flank of the mountain. One of the first results of the work of 1891 was the discovery of a calca-