AMERICAN GEOLOGY THE TACONIC QUESTION. 



673 



Upper Taconic;" also that this quartzite was a shore deposit formed 

 at the same time as were the silico-calcareous muds in deeper waters, 

 and which Emmons had included in his Upper Taconic. The Stock- 

 bridge limestone, which Emmons had regarded as a peculiar p re- 

 Silurian deposit, he showed on paleontological evidence to be the 

 equivalent of the Trenton, Chazy, and Calciferous limestones of the 

 Lower Silurian, 6 while the Talcose slate resting conformably upon the 

 Stockbridge limestone was found to contain graptolites of Hudson 

 River age. Emmons's subdivision of Upper Taconic he regarded as 

 merely due to a repetition of certain beds brought up by an overthrust 

 fault, as shown in fig. 140. 



Walcott in his summary of the paleontological evidence relative to 

 the Taconic, stated: (1) The trilobites described by Emmons in 1811- 



Fic v 140.— Tabular view of Taconic Strata as arranged by E. Emmons. (After C. D. Walcott. i 



1817 from the black slate were referred then to the highest member 

 of the Taconic system on stratigraphic evidence; but (2) in 1856 

 were, on evidence of the same kind, referred to the lowest member/' 

 (3) That in 1859 they were referred to a pre-Potsdam position"' by 

 comparison with a fauna whose position had been stratigraphically 

 determined with relation to the Silurian fauna. Further, (1) that the 



« These are now accepted as basal Lower Cambrian. 



h But, later, Foerste and Wolff found Lower Cambrian forms near the base of these 

 rocks at Rutland, Vermont. 



c Subsequent studies seem to show that Emmons was correct in this. 

 d Thej r are to-day referred to the Lower Cambrian. 

 NAT MUS 1904 43 



