402 
GEOLOGY OF THE FIRST DISTRICT. 
ia a quarry north of the bridge. The limestone at this, and at some other localities of this 
rock, is glazed with a thin black brilliant coating, that seems to be anthracite. 
Another locality is near Canaan centre, where the excavations of the railroad have cut 
through these rocks. 
At all these localities, the rocks are inclined at a high angle, and interstratified between 
other rocks belonging to the Champlain division. 
Fossil Remains of the Trenton limestone. 
Some species have been observed in the First district, that are believed to be undescribed, 
and may be expected to be figured and described in the Palceontological Report. 
The following list contains some of the fossils of this group : 
Isotelus gigas. 
Calymenc senafia. 
Cryptolithus tessellatus. 
Favosites lycopodites. 
— several species. 
Crinoidea, several species. 
Orthocera striatum. 
— duplex (C.). 
Trocholites amraonius (C.). 
— several species. 
Bellerophon apertus. 
Strophomena alternata. 
— semiovalis. 
— deltoidea. 
Delthyris microptera, 
Atrypa glabella. 
Orthis testudinaria. 
The above names are from Prof. Vanuxem’s Report, and most of them were given by him. 
4. Black-river Limestone. 
.Synonims. Mohawk limestone., Birdseye limestone, Base of the Trenton limestone, Bald mountain 
limestone. Blue limestone, Chazy limestone. Black marble of Isle la Motte, Sevenfoot tier, and 
perhaps the Neeleytown limestone, of the Geological Reports of New-York; Metalliferous lime- 
rock, Transition chequered and Sparry limerocks of Eaton. No 2, of the Pennsylvania Survey. 
Mohawk limestone. 
This rock is more extensively developed in the First district, than the Trenton limestone. 
It is grey and compact, ‘or subcrystalline in some places ; in others, a blue compact limestone. 
It ranges through Saratoga and Washington counties, along the base of the mountains of 
primitive rocks, resting on the projecting points, and dipping to the south ; but in the valleys, 
up which the strata are more or less extensively developed, they dip to the east-southeast with 
the primary, and on the east side of some of the valleys seem to plunge under these crystal¬ 
line rocks. 
