VERMONT AND WESTEKN MASisACUUSETTS. 461 



1846 ; and therefore the use of the same f,'eographical designation hy Dr. 

 Hunt, in 1871, for the Huronian, is both inappropriate and improper, on ac- 

 count of prior usage. The Green Mountains are not Huronian at all, though 

 flanked by it upon both sides in the northern half of Vermont. They belong 

 to the Montalban series. Adopting the principle of inversion, as applied to 

 the members of the Quebec group, we find they overlie these Montalban 

 gneisses in the proper order of succession. As Macfarlan says, those who once 

 accepted the theory of the metamorphism of New Enghmd seem to retain 

 erroneous notions of the age of the successive mountain ranges, calling the 

 Green Mountains newer than the Adirondacks, and the "White more recent 

 than the Green. They are both nearer the Laurentian than the Huronian, in 

 respect to age." (Geol. ot N. H., 1877, II., pp. 463, 464 ; see also pp. 10, 11, 

 25-27, 31.) 



In 1875 he said : — 



" His observations led him to believe that Emmons tmderstood the strati- 

 graphical relations of these rocks (many of them called Taconic by him) better 

 than most of his contemporaries." (See Proc. Bost. Soc. Nat. Hist., 1875, 

 XVIII., pp. 191-193.) 



Professor Dana in a series of papers bearing the title of " On the Geo- 

 logical Eelations of the Limestone Belts of Westchester County, Xew 

 York," (Am. Jour. Sci., 1880, (3) XX., pp. 21-32, 194-220, 3-59-375, 

 450-456; 1881, XXL, pp. 425-443; XXIL, pp. 103-119,) has brought 

 together the evidence bearing on the question of the geological age of 

 the Green Mountain limestones and associated rocks. He remarks as 

 follows : — 



" As the fossils of the limestone had been discovered only in Vermont, it was 

 required, in order to extend the conclusions to the rest of the Green Mountain 

 region, that the Vermont limestone should be proved to be the same strati- 

 graphically with that of the region to the south, and this was done by ascer- 

 taining (1) the essential continuity of the limestone from the north to the south 

 and south-southwest ; and (2) its association with similar rocks from north to 

 south, under similar stratigraphical relations ; and finally (3), by the discov- 

 ery of Lower Silurian fossils in the part of these belts of limestone that reach 

 into and beyond Dutchess County, and also in the associated Taconic schists of 

 that County. By these means, it has been shown that the schists of the 

 Taconic range, the limestone belts on either side, and various conformable 

 schistose rocks and limestone belts farther east and west, are conqirised witliin 

 the Lower Silurian formation, and that the whole series was displaced together 

 in the upturning and metamorphism by which the Green Mountains were 

 made." (Am. Jour. Sci., 1880, (3) XX., p. 22.) 



Professor Dana comes to the conclusion, that the limestone of West- 

 chester County and New York Island, and the conformably associated 



