446 STRATIGRAPHICAL GEOLOGY. 



for the sandstone, though the north-westerly dip of the quartzite, near 

 Otter pond in Gill, is suggestive of the existence of an underlying syn- 

 clinal. The area of the sandstone is much restricted from its representa- 

 tion on the Massachusetts map, in consequence of the discovery of the 

 harder rocks in Gill. The north end of the Trias in Northfield is com- 

 posed of a very coarse conglomerate, and is regarded as the uppermost 

 member of the series. 



There are several lenticular-shaped drift hills in Gill and Bernardston, 

 noted upon the map, which may be regarded as ancient glacial moraines, 

 and therefore devoid of ledges. They constitute a feature in surface 

 geology hitherto overlooked; and their presence here makes it certain 

 that no ledges will be found upon their surfaces. Prof. Dana speaks of 

 seeing a ledge of gneiss upon one of these drift hills (D D' of his map), 

 which must be a loose fragment, though of large size. Another class of 

 drift deposits occur along the railroad east of Bernardston village, which, 

 equally with the moraines, obscure our knowledge of the ledges ; but 

 enough of the outcrops are visible to make clear how the solid strata 

 in the neighborhood of the fossiliferous band are to be grouped. The 

 alluvium is not represented except where it is so abundant as to conceal 

 the underlying ledges, and make it uncertain what formation properly 

 belongs there. 



Catalogue of Specimens from the Helderberg Area. 



In the museum the specimens are labelled looi, 1002, etc., to 1192, but 

 upon the map the figures commence with i, 2, etc. In all other respects 

 the map resembles those drawn heretofore to illustrate the Coos, White 

 Mountain, and Ammonoosuc districts, 



BETHLEHEM GNEISS. 11, Limestone. 



Vernon. Bernardston. 



1, Gneiss, with much mica and pyrites. 13, 15, 65, Gneiss, very siliceous. 



2, 5, 8, 12, 58, Granitic gneiss. Hinsdale. 



3, Gneiss, very talcose. 20-27, 29-36, 39-43. 45- Granitic gneiss. 



4, Hornblendic gneiss. 27a, Feldspathic gneiss. 



6, Gneiss resembling Montalban. 28, Ferruginous gneiss. 



7, Gneiss, with dark mica. 37, 38, Conglomerate gneiss. 

 9, 10, Gneiss, very siliceous. 44, Gneiss, very siliceous. 



