1873. 307 [Hitchesck. 
Huronian age. It stands nearly vertical, adjacent to horizontal masses 
of feldspar. The exposures were carefully examined, and seemed 
to us to indicate that the vertical strata had been elevated since 
the deposition of the horizontal measures. No other exposures yet 
seen throw any light upon the relations of the Huronian to the 
Labrador. Our impression is that the Labrador rocks are the oldest. 
No fossils have been found in any of the series next in order. A 
large part of Rockingham county is underlaid by a mica schist. It 
extends into Belknap county, or to Winnepiseogee river east of the 
Merrimac river, and west of the latter stream it lies in synclinal val- 
leys of the older gneiss. The southeastern border is flanked by a 
range of syenite similar to that found in Quincy, Mass. The Merri- 
mac group is a convenient term to represent the quartzites and fine 
grained mica schist following the Merrimac river below Lowell. It 
occupies the entire country between the Exeter syenite range and 
the ocean, and resembles the mica schist so much that they were 
formerly supposed by us to be identical. Some of the ledges resemble 
those yielding fossils elsewhere. 
The Coos group deserves extended mention. It embraces the 
“calciferous mica schist” of eastern Vermont, the hard mica schist 
of Essex county, Vt., the softer slates of northern Cods county, to- 
gether with the various slates and schists holding staurolite as far as 
Massachusetts and adjoining Connecticut river, and various patches 
of andalusite slate on Mount Washineton, Mount Monadnock, Mount 
Kearsage in Warner, Rochester, ete. A large number of sections 
crossing these rocks in the two States were exhibited, the object of 
which was to illustrate a suggestion of Dr. Hunt that the calcareous 
rocks of Vermont may be identical with the staurolite members in 
New Hampshire. The sections also indicate that a quartzite and 
hornblende schist constitute the basal members of the Cods group. 
The latter is the band of rock immediately overlying the eneiss at 
Shelburne Falls, Mass., as described by me before this Society in 
1858, 1 and the two varieties of mica schist then spoken of belong to 
the same group. 
On account of the folded character of our New England formations, 
the sections just alluded to show numerous cases of inverted syn- 
clinals. A typical section shows parallel bands of Huronian rocks, 
the one along Connecticut river and the other near the Green Moun- 
1Proc., Vol. VI., p. 330. 
