428 STRATIGRAPHICAL GEOLOGY. 



cuts the granite near the station, but it extends only a short distance on 

 either side. It extends to the top of the hill ; but on the north side, a 

 few rods from the summit, the schist comes in contact with it. The 

 granite east to the base of the hill and a narrow band are crossed by the 

 railroad nearly opposite school-house No. 12. 



HELDERBERG SECTION OF THE CONNECTICUT VALLEY. 



For the sake of properly setting forth the relations of the interesting 

 series of Helderberg rocks at Bernardston, Mass., to the older New 

 Hampshire schists more or less associated with them, I propose to de- 

 scribe the formations between Chesterfield or Brattleboro', Vt., and the 

 fossiliferous group in Bernardston in a special section, having reference 

 to the question how far the rocks connected with the crinoidal limestone 

 are of the same age with it. The towns concerned are Hinsdale, Ches- 

 terfield, and Winchester, N. H., Brattleboro', Vernon, and Guilford, Vt, 

 and Northfield and Bernardston, Mass. The area comprises about ninety 

 square miles. Being at the boundary of the states of New Hampshire, 

 Vermont, and Massachusetts, the several geologists have mostly confined 

 their explorations to their respective territories, and I regret not to have 

 been able to study the towns outside of New Hampshire as thoroughly 

 as is desirable. The formations represented in this area upon a special 

 map, with contours, Plate XVHI, are the following: i. Bethlehem gneiss. 

 2. Hornblende rocks. 3. Cambrian slates with siliceous beds. 4. Quartz- 

 ite. 5. Coos slates and schists. 6. The Helderberg limestone and its 

 accompaniments. 7. Trias. 8. Alluvium. The sixth of these groups 

 has been known for nearly fifty years ; and we have on record the views 

 of E. Hitchcock, Sir Charles Lyell, James Hall, J. D. Dana, J. P. Lesley, 

 and others respecting it. The other formations have been examined very 

 slightly, principally those in Vernon and Guilford, and are described in 

 the report of the geological survey of Vermont, 1861. 



I. Bethlehem Gneiss. 



The gneiss of Vernon and Hinsdale presents such a likeness to the 

 Bethlehem group in New Hampshire, that I refer it to that series without 

 hesitation. Connecticut river flows transversely across this area in Ver- 

 non and Hinsdale. The level of the surface outcrops is invariably quite 



