230 C. D. Walcott — The Taconic System of Emmons. 



With the preceding statements in mind, I take up the ques- 

 tion of the "Taconic System" in geology, as one that can only 

 be intelligently understood and decided by the application of 

 the principles contained in them. 



In pursuance of a general plan the subject matter is arranged 

 under the following heads : 



1. The Taconic. Area and geologic work within it. 



2. Geology of the Taconic Area as known at the present time. 



3. Geology of the Taconic Area, as known to Dr. Emmons. 



4. Comparison and discussion. 



5. Nomenclature. 



THE TACONIC AEEA AND GEOLOGIC WORK WITHIN IT. 



The Taconic Area. — The Taconic, area includes the Taconic 

 range which trends north and south, nearly on the boundary 

 line between the States of ]STew York, Vermont, Massachusetts, 

 and Connecticut, and the country immediately adjacent to the 

 range, on the east and west. In this area Dr. Emmons first 

 studied and elaborated the theory of the " Taconic System " of 

 rocks. 



For the purpose of re- investigation the counties of Wash- 

 ington, and Rensselaer, N". Y., Bennington, Vt., and Berkshire, 

 Mass., were taken as the typical Taconic area, as they contain 

 sections of all the formations spoken of by Dr. Emmons and, 

 also, nearly all the localities cited by him, where the facts sus- 

 taining the theory which he proposed could be verified. 



Geologic work within the Taconic Area* — Quite early in 

 the course of my study of the history of the investigation of the 

 strata now referred to the Cambrian System in America I be- 

 came acquainted with the voluminous literature of the Taconic 

 controversy, and learned that two geologists only had studied the 

 typical Taconic area with any considerable degree of thorough- 

 ness. They were : Dr. Emmons, who founded the " Taconic 

 System " as the result of his observations, and Professor James 

 D.Dana, who studied the strata referred to the "Lower Ta 

 conic " by Dr. Emmons. Before Dr. Emmons entered the 



* For an historical review of the field work and also of the opiuions relating 

 to the " Taconic System " the reader is referred to Dr. Emmons's memoir in the 

 Agric. N. T., vol. i, 1847, and to the review of the Taconic System in his Amer- 

 ican Geology, pt. 2, 1856: also to. the various publications of Prof. Jules Marcou 

 on the Taconic System, especially " The Taconic System and its position in Strati- 

 graphic Geology" (Proc. Amer. Acad. Sci. and Arts, vol. xii, 1885); to Dr. T. S. 

 Hunt's memoir on "The Taconic Question in Geology " (Mineral Physiology and 

 Physiography, pp. 516-686, 1S86), also, "The Taconic Question Restated" (Amer. 

 Nat. Feb., March and April, vol. xxi, 1887); Prof. Jas. D. Dana's paper on "The 

 History of Taconic investigation previous to the work of Prof. Emmons " (Amer. 

 Jour. Sci., Ill, vol. xxxi, pp. 399-401, 1886), and many references in the series of 

 papers on the results of original investigations in the Taconic area, published from 

 1872 to 1887, by Prof. Dana. 



