266 RECORD OF SCIENCE FOR 1887 AND 1888. 



James Hall, Yanuxem, Hunt, Marcou, Barrande, and Logan were the 

 chief disputants in the early part of the discussion, and in its later 

 stages the more prominent participants were Dana, Billings, Hall, Hunt, 

 Hitchcock, W. B. Dwight, Dale, Bishop, Ford, O. D. Walcott, with a 

 number of other writers, who as advocates or opponents, have defended 

 or opposed those more immediately engaged in the investigations. 



The original idea was the erection of a new system stratigraphically 

 anterior to the then i)rominent " New York system" (1842), and at first 

 fossils did not enter into the consideration, but the character and the 

 stratigraphical position of the rocks were alone considered, the suppo- 

 sition being that the" Taconic system " was an unfossiliferous series 

 of rocks lying above the Primordial, but below the fossiliferous Palaeo- 

 zoic rocks. Early in the discussion fossils were discovered, which caused 

 the "Taconic system" to come into competition with the " Cambrian 

 system" of Sedgwick, but it was not until comparatively recently that 

 the rocks of the so-called " Taconic system " were known to contain 

 fossils of the Lower Silurian or " Champlain Division " of the early 

 New York geologists. The investigations of the last few years, mainly 

 by the discovery of fossils, have conclusively shown that the rocks in- 

 cluded in the "Taconic system " of Emmons are stratigraphically partly 

 anterior but in a large measure newer than the Potsdam sandstone; 

 that they are disturbed, metamorphosed, faulted, and do not constitute 

 a continuous series of rocks, but several interrupted masses. The im- 

 propriety of retaining the name has been elucidated by the evidence of 

 fossils, by showing that the rocks called " Taconic " by Emmons do not 

 constitute a geological system, as the term is applied by geologists, in 

 that they are made up of rocks belonging to several geological horizons, 

 separated by breaks in the series, and that " the system " as conceived 

 by Emmons is not pre-Potsdam, but contains some rocks as much above 

 as others are below that horizon. Hence, if the term " Taconic system " 

 were to be adopted, if used in the original sense, it would not be ap- 

 plicable to any other known series of rocks ; if modified to fit it to 

 modern facts, it would not be applicable to the Taconic area. 



Although defended by strong advocates on the geological side, the 

 settlement of the problem is due chiefly to palajontology, and the pro- 

 longed extension of the dispute has resulted from the absence of the 

 palteontological evidence which has come to light chiefly through the 

 investigations of Messrs. Dwight, Dana, Ford, Bishop, and Walcott. 



During the years 1887 and 1888 the following papers of a more or less 

 paljBontological nature were written upon this subject. Mr. J. P. Bishop 

 (17) had shown in 1886 by fossils that the fossiliferous limestones occur- 

 ring in Columbia County, on the western border of the Taconic slates, 

 were of the age of the Hudson River shales. 



C. D. Walcott (257, 2G0, 262) gives an account of the fossils discovered 

 in the lowest quartzites, in the limestones, and in the Upper Taconic of 

 Emmons. 



