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



age assigned to it by Dr. Emmons. In 1844 he incorporated 

 a great series of slates and shales belonging to another geologic 

 system by extending his sections across the western belt of the 

 Hudson Terrane, that limited the section of 1842, and on west 

 to the next line of outcrop of Lower Silurian rocks. This 

 addition gave the opportunity to separate off the "Upper 

 Taconic" in 1856. I have shown that all his reasons for call- 

 ing this series pre-Potsdam were based on errors of strati- 

 graphy ; and that it was a fortunate happening that any por- 

 tion of the " Upper Taconic " rocks occur where he placed 

 them in his stratigraphic scheme. Even if there were no 

 errors to vitiate Dr. Emmons's argument for the pre-Potsdam 

 position of the " Upper Taconic," that portion of his system 

 could not retain the name " Taconic ;" for it belongs to a dif- 

 ferent stratigraphic system from that to which the strata of 

 the Taconic range belong and to which he gave the name 

 " Taconic." 



Section V, of Plate XI, represents a section of strata a few 

 miles south of Burlington, Vt., and includes, not the " Taconic 

 System" of the first five sections and the text by Dr. Emmons 

 in 1842, but strata entirely disconnected £rom the original 

 Taconic, which, nineteen years later, was proven to belong in 

 part to the "Upper Taconic." This section is not mentioned 

 in the text, but it is evidently considered as exhibiting the 

 same relative geologic section as the other sections, a view that 

 is substantiated by the name " Taconic slate " being given to 

 the strata referred to the " Taconic System." There is not any 

 stratigraphic connection between the Vermont section (No. 5) 

 and the sections in the Taconic area (see map), and until 1859 

 there was not any paleontologic evidence that the slates of sec- 

 tion 5 were or were not of the same geologic age as the " Ta- 

 conic slates " of the five other sections and the text. In 1859 

 the publication of the Olenellus fauna by Professor Hall, 

 proved that Dr. Emmons was mistaken in referring the Ver- 

 mont slates, of section 5,« to his Taconic System of 1842. I do 

 not think that we can admit as evidence in favor of the strata 

 of the " Upper Taconic " having been described in the original 

 work of 1842, such an erroneous identification of a section that 

 had at the time no stratigraphic or paleontologic connection 

 with the original Taconic System. 



It was not until the field work, in the fall of 1887, was con- 

 cluded that I arrived at the above conclusions. Professor 

 Dana reached it long before, and Dr. T. S. Hunt holds that the 

 "Lower Taconic" is the typical Taconic. It matters not 

 whether geologists agree to restrict the test of what the origi- 

 nal Taconic was to the original Taconic of 1842 or hold that 

 Dr. Emmons had the right to add the strata separated off into 



