52 Co. tal HM I CIM EC OCI 
lines—and our observations were never extended so far as to be 
able to declare that these differences were of importance. 
Of the mica schists one range abounded in /fdrolite, a second 
in andalusite, and a third in staurolite. No two of these minerals 
were combined in the same set of schists, while all the bands are 
related to one another. The hydro-mica-schist group contained 
associated bands of chlorite schist, quartzites, bedded diorites, 
diabases and protogenes; and had before our time been known 
as ‘‘talcose slate.’’ No local term was applied to this complex, 
as it was supposed to represent the Huronian group of Canada, 
with which it had strong points of resemblance. Hornblende-schist 
proved to be common, and, with some misgiving, was relegated 
to the base of the hydro-mica groups. These several groups of 
schists were believed to belong to as many distinct periods of 
growth, each with its peculiar conditions. 
Inasmuch as the formations possessed northerly trends, sec- 
tions in east and west lines would most economically represent 
their structure, and hence the Dartmouth museum has a special 
large case prepared upon which fifteen sections are arranged in 
geographical order extending from Maine to New York across 
New Hampshire and Vermont. This collection contains about 
3000 specimens, which are still further elucidated by geologically 
colored profiles and a large relief map. 
A second principle employed was the discovery that the crys- 
talline schists of New England tended to assume ovoidal shapes 
exhibiting a banded structure. Reference was made to the groups 
of Percival in Connecticut, K,, K,and K,, as well as to the B 
of the Eastern Primary. The center of the oval seems to be the 
oldest part. Dr. A. C. Lawson* describes similar areas in the 
Rainy Lake district north of Lake Superior, as does Professor A. 
Winchell? in Minnesota and Professor B. K. Emerson in western 
Massachusetts. 
As there is no readily recognizable base to the New Hamp- 
shire rocks, it was found necessary to fix upon some convenient 
t Ann. Rept. Geol. Can., 1887. 
2 Bull. Geol. Soc. Amer., Vol. I., p. 361. 
3 [bid., p. 559. 
