History of the Quebec Groiqi. — Hunt. 215 
primary rocks, regarded the crystalline schists of the Green 
mountains as altered paleozoic strata, the metamorphosis of 
which he declared to have been effected by intrusive serpen- 
tines and intrusive quartzites. 
As regards the geological horizon of the paleozoic sediments 
in question, Ave may note that Amos Eaton maintained the ex- 
istence in the region in debate of two distinct series each con- 
sisting princijjally of argillites and sandstones, which he called 
the First and Second Graywackes, much resembling each other; 
the first of these being below the horizon of the Trenton 
limestone, and the second above it, or between this same and 
the Niagara limestone. The absence of such a Graywacke se- 
ries in parts of New York below the Trenton led Mather to 
deny its existence, and to confound in one group the First 
and Second Graywackes along the Hudson valley, under the 
common name of the Hudson slates (called collectively by 
Vanuxem, the Hudson-River group) ; which were assumed to 
be the equivalent of the Loraine shales, with the addition of 
the Utica shale below and the Gray or Oneida sandstone above* 
Mather's view of the post-Trenton age of the whole of the 
Hudson River Graywacke and of its extension north and east 
through Vermont to the city of Quebec, was accepted by James 
Hall, by C. B. Adams, by W. B. Rogers, and for a time by Em- 
mons himself; who, in his final report in 1842 on the geology 
of the Northern District of New York, describes the rocks at 
Quebec as Loraine shales with their overlying sandstones, 
which he speaks of as extending from the valley of the Hud- 
son through eastern Vermont to the city of Quebec. In anoth- 
er chapter of the same volume, however, Emmons reverts to 
the teaching of Eaton, and in his subsequent writings includes 
these rocks in the First Graywacke — his Upper Taconic series. 
This view, however, was not accepted by other geologists. 
James Hall continued to maintain Mather's doctrine of the 
post-Trenton age of the Graywacke series in question. C. B. 
Adams, charged with a geological survey of Vermont, held in 
1846 that the Red Sandrock of that state, "now included by 
Emmons in the First Graywacke or Upper Taconic, is of "the 
period of the Medina sandstone and the Clinton grou])S," 
while W. B. Rogers, in 1851, considered that limestones, 
which near Burlington, Vermont, are associated with this Red 
Sandrock are probably "of the Medina group." 
