OZ REGINALD ALDWORTH DALY 
mountain-built strata is the well-known one at Bernardston, 
Mass., some seven miles to the southwest of the Ashuelot area. 
The first studies of the organic forms enclosed in the limestones 
at this place referred them to the Helderberg or lower Devon- 
ian. More recent determinations now fix the age of the lime- 
stones as being at the Hamilton-Chemung stage of the Upper 
Devonian. They are folded up with quartzites and mica- and 
hornblende-schists which are intensely metamorphic. The care- 
ful field work of Professor Emerson and of the late Professor 
Dana has shown that these metamorphic rocks are a part of the 
same terrane which throughout this paper and the survey 
reports of the New Hampshire survey has been called the 
‘“Coés group.” As early as 1873, Dana concluded that “the 
Bernardston, South Vernon, and Northfield beds being of Hel- 
derberg age, the Coéds group, which is but the northern contin- 
uation of the same series, is, if correctly traced out, also Helder- 
berg.”’* Professor C. H. Hitchcock adopted this view, although 
he disagreed with Dana as to the stratigraphic order of the 
rocks adjacent to the limestones.?_ Professor Emerson followed 
with the publication of his results after a painstaking lithological 
and structural study of the whole area. In this paper he most 
emphatically states his conviction and advances new proof that 
Dana’s position was the correct one. Two years later Dana 
reiterated his opinion,‘ and in his last and greatest work clearly 
shows that it persisted for the rest of his lifes Professor Emer- 
son is inclined to place the faults and folds which dislocate the 
Bernardston rocks in Carboniferous or post-Carboniferous time. 
He attains this result by combining his observations at Bernard- 
ston with those in the more richly fossiliferous localities farther 
south, in the state of Massachusetts. Thus we may conclude 
that the porphyritic granite is probably a post-Carboniferous 
t Am. Jour. Sci. (3), Vol. VI, 1873, p. 349. 
2Am. Jour. Sci. (3), Vol. XIV, 1877, p. 380. 
3 Am. Jour. Sci. (3), Vol. XL, 1890, pp. 263 and 366; especially p. 366. 
4 [bid. (3), Vol. XLIII, 1892, p. 456. 
5 Manual of Geology, pp. 310, 325. 
