564 @. H. Hitchcock—Helderberg Rocks in-New Hampshire. 
gray in the interior. It dips apparently 50° east of north. 
The section is about half a mile long. 
Following the limestone southwest, perhaps a fourth of a 
mile, we find the purest carbonate of lime yet seen. is 1 
interrupted by chloritic rock, to be succeeded by fossiliferous 
slate and limestone, which passes west of the slate quarry an 
lower down the hill if its strike does not alter. Commencing 
near the fork in the road turning to the slate quarry, there 
is first the diabase on fig. 6, with its usual position; second, 
the Helderberg rocks just mentioned. The slates predominate 
and decompose readily and unequally. High up the hill is 
the gray sandstone decomposing white, continued from section 
5. The hornblende rock on the crest of the hill is one massive 
stratum, with no indication of divisional planes. The slates 
were at first thought to be the continuation of the quarry ledge 
on fig. 7. Both have the pyrites in abundance and the same 
general aspect. But by comparing the several figures together, it 
seems as if the sandstone would correspond with the conglom- 
erate back of the quarry, and the hornblende rocks agree with 
the green schist. That would make the slates just mentioned 
correspond with each other, as well as the harder dark slates 
in which a synclinal appears. : 
The latter slate is a hard, black, even-bedded rock, which 
. also shows itself continuously nearly to Parker Brook. The 
east part of the sync.inal is wanting in fig. 6, its supposed 
place being covered by the alluvium of the Ammonoosue. 
The strike varies to northwest near Mr. L. A. Parker's house, 
transversely as far as indicated; the eastern slope remains 
seebplored. 
cellent quality, and, were it not for a profusion of eubical 
crystals of pyrites, would be worth quarrying. It dips about 
80° southeasterly. Above it on the hill is an interesting con- 
ae glomerate, with pebbles averaging the size of a hen’s egg. The 
