STR UCTURE OF THE MO UNT WA SHING TON MA SS. 723 



In Professsor 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 remem- 

 bered, 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 

 1 89 1 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 moun- 

 tain. The work has been in charge of Professor Raphael Pum- 

 pelly, 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 concern- 

 ing 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- 



'On Taconic Rocks and Stratigraphy, with a Geological map of the Taconic 

 Region, J. D. Dana, Am. Jour. Sci., 1885 and 1887. 



2 Ibidem, 3d ser., vol. xxix., June, 1885. 



3 The Taconic System of Emmons, and the Use of the Name Taconic in Geologi- 

 cal Nomenclature, by Chas. D. Walcott, Am. Jour. Sci., vol. xxxv., pi. iii. (May, 

 li 



