CLARK: TACONIC REVOLUTION. 151 
occupies troughs in the older rocks. No indication of an erosional 
unconformity has come to my notice. 
Ammonoosuc District, N. H. — The most recent article on the 
geology of the fossiliferous Palaeozoic rocks around Littleton, 
N. H., is Lahee's description quoted below. This paper is chiefly 
valuable on account of the footnotes, which refer to practically 
all of the articles on this region. The only remark \vith which we 
are directlj' concerned is the following: 
"2. The Fitch Hill granite-gneiss is intrusive into the Lyman 
schists, but unconformably underlies the Niagaran sediments of 
Fitch Hill, Littleton, thus demonstrating the presence of a 
regional unconformity beneath the Upper Silurian strata of the 
Ammonoosuc district in New Hampshire."^ 
The Lyman schists were considered tentatively by Hitch- 
cock to be Cambrian or Ordovician, but they have yielded no 
fossils. A more comprehensive account of this region is Hitch- 
cock's "New Studies in the Ammonoosuc District of New Hamp- 
shire."^ With regard to the Lyman series, underlying the 
Silurian and Devonian rocks, Hitchcock recognized that "there 
is equal uncertainty as to the exact place of the supposed inferior 
schistose complex and the argillitic schists. At present the 
general term of Lower Silurian (Ordovician) may be applicable." 
It is difficult to see how the structure of this region has any 
bearing on late Ordovician mountain-building. If Lahee's ob- 
servations and conclusions are correct, it would seem that the 
Upper Silurian rocks were laid down in a sea transgressing ov- 
er a country long exposed to erosion, and that is all. 
Bernardston, Mass. — The geological history of the Ammonoo- 
suc district appears to be rather closely duplicated by that of the 
Bernardston region, except for the fact that no igneous injection 
complicates the latter. In each case we have an imderlying 
series of sedimentaiy rocks of unknown age, which have in each 
case been supposed to be Ordovician. These are followed in one 
case by upper Silurian and lower Devonian sediments, while at 
Bernardston only lower Devonian formations appear. 
'Lahee, P. H. Geologry of the new fossiliferous horizon and the under- 
lyin^j rocks, in Littleton, Now Ihunpshiro. Aitu>r. Joiirn. Sci., ser. 4, 
vol. 36, p. 234, 1913. 
'Hitchcock, C. H. Bull. Geol. Soc. Amer., vol. 15. p. 4GI-4S2, 1904. 
