CD. Walcott — The Taconic System of Emmons. 231 



field Professors Dewey and Amos Eaton had studied more or 

 less of the Taconic region, and the data obtained by them were 

 of material aid to Dr. Emmons. 



Among others who have examined portions of the area 

 studied by Dr. Emmons previous to 1844, are : Dr. W. W. 

 Mather, of the geological survey of New York, who made a 

 reconnoissance of the portion within New York State (Geol. 

 N. Y., Kep. Eirst Geol. Dist, 1812) ; Prof essor James Hall, who 

 examined a section crossing from the Hudson Elver to the 

 Green Mountains (Proc. Assoc. Am. Geol. and Nat., p. 68, 

 1815), and the Professors W. B. and H. D. Rogers who 

 studied a section extending from the Massachusetts side of the 

 Taconic area to the Hudson Piver (loc. cit., p. 67 : also, Proc. 

 Am. Phil. Soc, vol. ii, pp. 3 and 1, 1811). The Professors 

 Edward and C. H. Hitchcock described and mapped the strata 

 referred to the " Taconic System " in Vermont, and discussed 

 the question of their geologic age (Geol. Vt., 1862). Subse- 

 quently, Professor C. H. Hitchcock made a series of sections, 

 crossing the " Taconic System " in Vermont (Bull. Am. Mus. 

 Nat. Hist., vol. i, 1881). The observations made by Mr. S. W. 

 Eord, from 1874 to 1886, in the counties of Rensselaer and 

 Columbia, N. Y, have furnished important data on the forma- 

 tions examined by him that will be referred to again. Some 

 of the results obtained by the geologists mentioned will be 

 spoken of under the head of " Comparison and Discussion." 



Dr. T. Sterry Hunt, Professor Jules Mafcou and Professor 

 N. H. Winchell have all written at length upon the " Taconic 

 System," but I have been unable to discover that either of 

 these gentlemen have made any field observations in the typical 

 Taconic area * 



In searching for data to aid me in forming an opinion respect- 

 ing the value of the name Taconic in American geologic nom- 

 enclature, I found that there was such a wide divergence of 

 opinion among the geologists who had studied the " Taconic 

 System " in the field and those who had formed opinions upon 

 it from partial observations in other areas, and the data given 

 by Dr. Emmons and the Professors Hitchcock and Professor 

 Dana, that there seemed to be no way to settle the questions 

 at issue except by investigating the original Taconic area and 

 identifying and mapping all the formations within it except 

 the areas mapped by Professor Dana and the Professors Hitch- 

 cock. The necessity of ascertaining the age of the different 



* Dr. Hunt's later opinions appear to have been influenced by his geologic obser- 

 vations in Pennsylvania, and by certain theoretic views founded on the lithologic 

 characters of the " Lower Taconic " rocks. Professor Marcou examined the ex- 

 tension of . the "Upper Taconic ' ; strata in Northern Vermont and Professor 

 "Winchell appears to have studied the publications of Messrs. Emmons, Marcou and 

 Ford. 



