C. D. Walcott — The Tdconic System of Emmons. 323 



Resume of the Paleontologic Evidence. 



(1.) The trilobites described in 1844-47, from the "Black 

 Slate," were referred to the highest member of the " 'laconic 

 System," on stratigraphic evidence. 



(2.) The same trilobites were referred to the lowest member 

 of the " Upper Taconic," on stratigraphic evidence, in 1856. 



(3.) In 1859 they were for the first time referred to a p re- 

 Potsdam position by comparison with a fauna whose position 

 had been stratigraphically determined in relation to the Silu- 

 rian fauna. 



(4.) The Nereites and other trails with the exception of the 

 two from Washington County, N. Y., described as typical of 

 the " Taconic System," have not yet been stratigraphically 

 located in the geologic series. 



(5.) The graptolites referred to the " Taconic System " form 

 a portion of the fauna of the Hudson Terrane. 



Discussion. — There is not much opportunity for a discussion 

 of the geologic age and position of the " Lower Taconic " 

 rocks. The thorough work of Professor Dana practically set- 

 tled those points before I began my investigation. Dr. T. S. 

 Hunt opposed Professor Dana's conclusions, basing his dissent 

 pn the result of his own studies of the geology of southeastern 

 Pennsylvania and, on his acceptance of certain theoretic views 

 in regard to the lithology of the " Lower Taconic " rocks. He 

 argued that the " Lower Taconic " was the typical Taconic Sys- 

 tem and of Archean age,* and that Professor Dana's interpreta- 

 tion of the stratigraphy was not sufficient, without the aid of fos- 

 sils, in the typical Taconic region, to establish the Lower Silurian 

 age of the Stockbridge limestone or the crystalline marbles of the 

 Lower Taconic. With the facts presented in this paper, how- 

 ever, I do not think that Dr. Hunt can claim support for his 

 views without first substantiating them by researches in the 

 Taconic area, a matter that he has apparently not given his 

 attention, f heretofore. 



* ( :i Taconic Question in Geology;" Min. Physiology and Physiography, p. 

 582, paragraph 92, 1886). " 92. Considering the pre-OambriaD age of the Lower 

 Taconic to be established, as well as its distinctness alike from the older crystal- 

 line rocks below and from the Cambrian series above, to which Emmons had 

 given the name of Upper Taconic — it was proposed by the writer, in 1878, to 

 restrict the term Taconic — for which the alternative name of Taconian was then 

 suggested,— to the Lower Taconic of Emmons." For other views held by Dr. 

 Hunt, see Am. Jour. Sci., 3d ser., vol. xxxiii, pp. 417, 418, 1887. 



fSome of Dr. Hunt's errors consist: 1. In relying upon a lithologic theory 

 based upon observations made far distant from the Taconic area 2. His accept- 

 ance of Dr. Emmons's theory of the stratigraphic position of the " Lower Taconic" 

 strata without personal investigation when it was well known that all of Dr. 

 Emmons's contemporary geologists opposed the 1; Taconic" theory. 3. His assum- 

 ing that it was largely personal opposition to Dr. Emmons that led all geologists 

 who investigated the Taconic area to decide against the " Taconic" theory. 4. 

 His ignoring all stratigraphic and paleontologic evidence published by Professor 



