470 ADDRESS OF T. STERRY HUNT. 
This conclusion was confirmed by Billings, who, in 1861, after vis- 
iting the region and examining the organic remains of the Red 
sandrock, assigned to it a position near the horizon of the Pots- 
dam.* Certain trilobites found in this Red sandrock by Adams 
in 1847, were by Hall recognized as belonging to the European 
genus Conocephalus (= Conocephalites and Conocoryphe), whose 
geological horizon was then undetermined.; The formation in 
question consists in great part of a red or mottled granular dolo- 
mite, associated with beds of fucoidal sandstone, conglomerates 
and slates. These rocks were carefully examined by Logan in 
Swanton, Vermont, where, according to him, they have a thick- 
ness of 2200 feet, and include toward their base a mass of dark 
colored shales holding Olenellus with Conocephalites, Obolella, 
etc.; Conocephalites Teucer, Billings, being common to the shales 
and the red sandy beds.{ Many of these fossils are also found at 
Troy and at Bald Mountain, New York, where they accompany 
the Atops of Emmons, now recognized by Billings as a species of - 
Conocephalites. 
A similar condition of things extends northeastward along the : 
Appalachian region. On the south side of the St. Lawrence below 3 
Quebec a great thickness of limestones, sandstones, and slates, 
formerly referred to the Quebec group, is now regarded by Billings 
as, in part at least, of the Potsdam formation; while on the coast 
of Labrador, and in northern Newfoundland the same formation, 
characterized by the same fossils as in Vermont, is largely devel- 
oped, attaining in some parts, according to Murray, a thickness of 
3000 feet or more. Along the northern coast of the island it is 
nearly horizontal, and appears to be conformably overlaid by about 
4000 feet of fossiliferous strata representing the Calciferous sand- 
rock and the succeeding Levis formation. 
Mr. Billings has described a section from the Laurentian of 
Crown Point, New York, to Cornwall, Vermont, from which it ap- 
pears that to the eastward of a dislocation which brings up the 
Potsdam to overlie the higher members of the Champlain division, 
the Potsdam is itself overlaid, at a small angle, by a great mass of a 
limestones representing the Calciferous, and having at the summit a 
some of the characteristic fossils of the Levis formation. Next™ Hi 
eee 
ae Pere Cae ee eee a 
P ER ee ee ee OR 
* Amer. Jour. Sci., II, xxxii, 232. 
tIbid., II, xxxiii, 374. 
t Geology of Canada, 1863, p. 281. Amer. Jour, Sci., II, xlvi, 224. 
