142 DE. THOMAS STERÉT HUNT ON THÉ 



§ IVS. To sum up in a few words the views of the Metamorphic school forty years since 

 (1840-1846) : we find that H. D. and W. B. Eogers then maintained the paleozoic age of the 

 Lower Taconic series, of the "White Mountain gneisses and mica-schists, and also of the 

 crystalline limestones found among the gneisses of the New York and New Jersey High- 

 lauds, though admitting the primary age of these Highland gneisses. Mather, again, 

 while holding, in like manner, to the paleozoic age of the Lower Taconic, was not acquainted 

 with the White Mountain series, but maintained that the whole of the gneisses, mica- 

 schists and crystalline limestones of south-eastern New York, with the possible exception 

 of the Highland belt, were paleozoic, and of one age with the Taconic series. 



It is worthy of note that on the geological map of the State of New York, published 

 in 1842 " by legislative authority," of which the Southern District was prepared by Mather 

 himself there is no distinction of color between the gneissic rocks of the Highlands and 

 those lying adjacent to them on the south and east, described by him in his final Re- 

 port, in the following year, as metamorphic paleozoic strata. The serpentine of the region, 

 as seen in Staten Island, is colored on the map like the adjacent intrusive triassic diabase, " 

 but no attempt is there made to designate other eruptive rocks than these. 



§ 1*79. In opposition to the views of this Metamorphic school, there were not wanting 

 some, like Emmons and Charles T. Jackson, who maintained the Primitive age of the whole, 

 or a part, of these crystalline rocks of New England, though recognizing, as Eaton had 

 done, their lithological distinctness from the gneiss of the Adirondacks, and of the High- 

 lands of the Hudson. Already, moreover, in 1824, Bigsby had discovered, around Lake 

 Superior and beyond, the existence of two series of crystalline rocks, and distinguished 

 the younger of these as belonging to the Transition series. More than twenty years later 

 the Geological Survey of Canada, -while adopting for the crystalline rocks of New England, 

 and their extension into Canada, the hypothesis of their paleozoic age, reexamined these 

 Transition crystalline schists of Bigsby, as seen both on Lakes Superior and Huron, and on 

 the upper Ottawa, and described them as forming a distinct group between the base of 

 the paleozoic series and the ancient gneiss, upon which it was found to rest unconform- 

 ably. This intermediate series, first described in 184*7, was by the present writer designa- 

 ted, in 1855, by the name of Huronian, — the underlying gneissic series haviug, in 1854, 

 received the name of Laureutian. 



§ 180. In 1858 appeared the final Report of H. D. Rogers on the Geology of Pennsyl- 

 vania, in which we find no recognition of the extreme doctrines of metamorphism main- 

 tained by Mather in 1843, and by W. B. Rogers and himself in 1846. Not having come to 

 an understanding of the question of the First Gray wacke, H. D. Rogers regarded the Lower 

 Taconic series in Pennsylvania as an altered form of the Champlain division, and consid- 

 ered the granular quartz-rock with Scolithus to be the equivalent of the New York Pots- 

 dam sandstone.'-' The characteristic crystalline rocks of western New England and south- 

 eastern New York, described by Mather as altered paleozoic, pass beneath the mesozoic 

 sandstone in New Jersey and reappear in south-eastern Pennsylvania. These rocks were 

 now, in 1858, described by H. D. Rogers as forming two great groups, an older or so-called 



''' See, for details with regard to this and the other iîerpentines of the region, the present writer on the Geolog- 

 ical History of Serpentines, 1SS3, Trans. Roy. Soc. Canada, vol. i, sec. iv, pages 172-174. 



-* For Lesley's doubts as to the precise equivalence of the Primal quartzite of Pennsylvania and the New 

 York Potsdam, see Amer. Jour. Science, 1865, xxxix, 223. 



