134 DE. THOMAS STERRY HUNT ON THE 



and, farther, that the lower members of the Ordoviciau series, (the limestones of the Tren- 

 ton group), thiu ont and present irregularities to the south and east. Although, according 

 to Hall and Logan, it appeared that the line between the Loraine shales and the inferior 

 series passed from the east to the w^est bank of the Hudson near Hyde Park in Duchess 

 County, subsequent studies have shown the existence of the higher strata farther south- 

 ward, on the east bank." Dale, in 187*7, found fossils of the Loraine period in shales at 

 Poughkeepsie, and Dwight soon after detected abundant forms of Trenton age in the lime- 

 stone of the Wappinger valley, a little farther south, as well as at Newburg, on the west 

 bank of the Hudson. These discoveries were soon followed by that of a remarkable fauna 

 of Calciferous age in other limestones in the Wajipinger valley, thus showing the presence 

 here, as in Vermont, to the east of the outcrop of the Potsdam, of strata carrying the fos- 

 sils of the Calciferous, the Trenton and the Loraine subdivisions. These remarkable dis- 

 coveries by Dwight were made in 187*7-1880," and, joined to the observations of Dale, and 

 those of Ford, show the existence, in what has been called Hudson River group and Quebec 

 group, of fossiliferous strata ranging from the Lower Potsdam to the Loraine, both in- 

 clusive, — a result identical to that already arrived at in Canada for the area which had 

 been successively mapped as Hudson River groiix? and Quebec group. 



§ 159. Having thiis recalled the latest results of paleontological research among 

 the so-called Upper Taconic, and shown the association of areas of Ordovician rocks with 

 the predominant Cambrian, we may proceed to notice the views of Prof. J. D. Dana on 

 the Taconic question. He, in 1872 and 1873, published an extended series of papers on 

 the rocks of the Taconic I'ange, as seen in Berkshire County, Massachusetts, and reasoning 

 from the organic forms found in association with similar limestones in Vermont, reached 

 the conclusion that the Stockbridge limestone " is mainly Trenton," the overlying schists 

 being of the Hudson River group.'" This latter statement, supported by a stratigraphical 

 argument, may be found in a paper on the Greological Age of the Taconic System, in the 

 Quarterly Journal of the Geological Society of London, for August, 1882. Herein, giving 

 a historical introduction to the subject, Dana takes for a definition of the Taconic system 

 the statements made by Emmons in his G-eology of the Northern District of New York, 

 published in 1842, while his views were yet vague, and before he had clearly defined, or 

 even studied the relations of the granular quartz-rock, the granular lime-rock, and the 

 interstratifled and immediately overlying schists and argillites, together constituting the 

 Lower Taconic, with the great Grraywacke series which Eaton, Emmons, Mather and 

 Logan have alike placed above it, and which was subsequently called Upper Taconic by 

 Emmons. This latter series, as we have seen, appears along the western base of the 

 Taconic range, and presents a great mass of faulted and disturbed uncrystalline strata 

 between that range and the narrow band of Loraine shales which extends for a long 

 distance sovithward along the east bank of the Hvidson. 



§ 160. In describing, in 1842, the rocks of the Taconic range in western Massachusetts, 

 Emmons notices the occixrrence of three parallel belts of limestone, with accompanying 

 shales, the western one of which he designates as the Spany limestone — the Sparry lime- 



'^ Amer. Jour. Science, xvii, 5?. 



" Ibid., xvii. 389 ; xix, 50 ; xxi, 78 ; and xxvii, 249. 



"^ Ibid., vi, 274. 



