J. D. Dana— Geology of Vermont and Berkshire. 37 
cinnati) in age, a belt of color indicating Trenton extends; then 
others, more remote, for Chazy, Calciferous and Potsdam; and 
the Chazy east of the slate-belt extends two-thirds of the way 
to the quartzyte. These points in the map rest mainly on fos- 
sils, except the eastern boundary of the Chazy, and the periods 
t 
assigned to the part of the limestone still farther east. 
Art. VL—On the relations of the Geology of Vermont to that of 
Berkshire ; by JAMES D. DANa. 
sion there presented with regard to the age of the Berkshire 
rocks largely on the single discovery of Mr. A. Wing, of Chazy 
fossils in the West Rutland limestone, the only one of his 
that had then been made public. The wider knowledge 
of his discoveries which we now haye, through his notes and 
letters, gives a better basis for a decision, and I propose to con- 
sider the bearing of the facts as now understood. 
We have first to enquire what reasons there are for making 
the geology of Vermont a key to that of Berkshire. These are 
the northern of the series, are of political authority, not geologi- 
“si ps so are those of Massachusetts, Connecticut, and New 
ork, 3 
(1.) The Limestone formation.—The great limestone belt of 
Vermont stretches southward, without interruption or dimin- 
ished width, into Berkshire Co., Massachusetts; throug’ 
kshire, into Western Connecticut; and, continuing its south- 
by-west trend over Canaan and Salisbury, it passes out of Con- 
hecticut, still as wide as in any more northern part, into eastern 
New York, over the towns of. Amenia and Dover, to Pawling. 
Thence it still stretches southward for seven or eight miles, but 
* Vol. iv, 362, 450, (504); v, 47, 84; vi, 257. 
