836 



DYNAMICAL GEOLOGY. 



H. D. & W. B. Rogers: Proc Amer. Phil. Soc, Jan. 1, 1841; make the slates of 

 the Taconic Mountains and the rocks east and west to be Lower Silurian, and refer the 

 slates to the Hudson River group. — W. W. Mather : Report Geol. N. York, 4to, 

 1843 ; gives many sections and announces the same conclusions, arguing against the 

 Taconic system. — H. D. Rogers : Address, etc., Rep. Amer. Assoc. Geol. & Nat., for 

 1844, p. 67, and Amer. J. Sci., xlvii., 137, 1844; urges the same views essentially. — 

 James Hall: ibid., p. 68. 



T. S. Hunt, "of the Geological Commission of Canada." : On the Taconic System, 

 Report Amer. Assoc, for 1850 (New Haven meeting), says, " The results of the 

 [Canada] survey have shown, as I had the honor to state at the last annual meeting at 

 Cambridge [in 1849], that the Green Mountain rocks are nothing else than the rocks of 

 the Hudson River group with the Shawangunk conglomerates, in a metamorphic con- 

 dition." — James Hall: N. Y. Palaeontology, vol. hi., p. 15, 1859. — T. S. Hunt: 

 Amer. J. Sci., II., xxxi., 402, 1861 (after Logan's defining of the Quebec group); says, 

 "the Quebec group with its underlying shales is no other than the Taconic system of 

 Emmons." — Idem: ibid., xxxii., 427, 1861; makes the Taconic, exclusive of the 

 slates, equivalent of the Calciferous, adding that " it remains to be seen whether Dr. 

 Emmons can retain from the wreck of his system, the lower slates as a Taconic forma- 

 tion older than the Potsdam." — W. E. Logan : Geology of Canada, 8vo, 1863, p. 934; 

 makes the system to consist, " for the greater part at least, of the strata of the Potsdam 

 and Quebec Group." — J. D. Dana: Manual of Geology, 1863; cites ard adopts the 

 views just mentioned. — E. & C. H. Hitchcock: Report on the Geology of Vermont, 

 2 vols., 8vo, 1861, and Amer. J. Sci., HI., xix., 236, 1880. —James Hall and W. E. 

 Logan: Amer. J. Sci., IL, xxxix., 96, 1865; refer the Hudson River slates south of 

 Albany to the Quebec group. — T. S. Hunt: Address, etc., Rep. Amer. Assoc, for 

 1871; refers the Stockbridge or Green Mountain limestone to the Quebec group, and 

 states that the conclusion of Rogers and Mather referring the Taconic system to the 

 "Cham plain Division " of the New York rocks had been sustained by subsequent ob- 

 servations (pp. 15 and 23). 



J. D. Dana : On the Rocks of the vicinity of Great Barrington, Mass., Amer. J. Sci., 

 III., iv., v., vi., 1872, 1873; gives sections showing the conformability of the Taconic 

 slates, " magnesia schists " (slates and schists making the Taconic Mountains), Stock- 

 bridge limestone, and quartzyte (the original Taconic rocks of Emmons), and makes 

 the limestone (on the basis of Billings's report of Wing's discoveries), Trenton and 

 Chazy, and the Taconic schists and slates of Hudson River age. — A . Wing : Discov- 

 eries in Vermont, ibid., xiii., 1877; shows, by their fossils, that the "Stockbridge lime- 

 stone " and " Sparry limestone " of the Taconic System of Emmons in Vermont, are 

 Lower Silurian, from Potsdam to Trenton, inclusive, and that the Taconic slates overlie 

 the limestones. — J. D. Dana : On the Relations of the Geology of Vermont to that of 

 Berkshire, ibid., xiv., 1877; gives new sections proving the conformability before an- 

 nounced, and sustains the conclusion that the Taconic schists and slates (those of the 

 Taconic Mountains) are of Hudson River age, and the limestones Lower Silurian. — 

 Frederick Prime, Jr. : Lower Silurian Fossils in Limestone associated with Hydromica 

 Slates in Eastern Pennsylvania, ibid., xv.,261, 1878; shows the Chazy, or Trenton age 

 of the rocks, which are part of the so-called Taconic and like those of Berkshire. — T. 

 Nelson Dale : Discovery of fossils, proving the Hudson River age of the supposed Ta- 

 conic Poughkeepsie slates. — J. D. Dana: On the Hudson River, Age of the Taconic 

 schists, ibid., xvii., 375, 1879; announces the discover}' of Trenton fossils in the Bar- 

 negat or Wappinger Valley limestone (which adjoins the Poughkeepsie slates), and 

 proves the conformabilit}'- of the Poughkeepsie slates with the slates of the Taconic 

 Mountains, as exhibited in Mather's sections and the continuity of the Dutchess County 

 slates and limestones with those of the Taconic System of Massachusetts and Vermont. 

 — W. B. D wight : Fossils of the Wappinger Valley Limestone, ibid., 389; adds to the 

 number of localities, and gives lists of Trenton fossils. — Whitfield : On the occur- 

 rence of Maclurea of the Chazy beds in the Barnegat Limestone near Newburgh, New 

 York, Amer. J. Sci., xvii., 1879. 



