430 STRATIGRM'IIICAL GKOLOGY, 



At saw-mill near S. Tlionias's, northerly. South-east from village, N. 44° W. and 



Winchester. 50° !•:. 



At west edge o{ formation, 50° iN. 30° W. ; Warwick. 



25° N. 40° W. ; 20° N. 40° \V. At west edge of the town, 20° N. 12° W. 



Northficld. 

 At the west edge, do'^ northerly. 



Tlic gneiss of the kisl thi-co towns Ijclon^^s to a range not mentioned 

 above, bordering- the Ilelderberg field on the cast. It is very likely of 

 the same age with the typical area in Hinsdale and Vernon. The dips 

 indicate a synclinal between the Vernon and Winchester areas, thus con- 

 firming the suggestion of their identity. I have not included certain 

 gneisses in Vernon and Northficld associated intimately with the quartz- 

 ite, believing them to belong to the latter series of rocks. They differ in 

 the absence of the talcose mineral and in being fine-grained, scarcely dis- 

 tinguishable from the quartzite. 



The principal variation from the east dip is in the first two observa- 

 tions. Here, there is abed of crystalline limestone in the gneiss quite 

 near the border of the area, and, as usual, overlaid by hornblendic rock. 

 The southerly dip of these strata beneath quartzite and mica schist agrees 

 with our theory of the inversion and greater antiquity of the gneiss. The 

 limestone presents a slight likeness to the ]5crnardston rock; but a care- 

 ful examination did not reveal the existence of any fossils. The Bethle- 

 hem group in Orford and Lyme carries a very large bed of limestone, 

 which may be the analogue of this. Likewise, any bands of quartzite not 

 readily separated from the gneiss might be regarded as the equivalents 

 of the quartz seen at Hanover in it. 



The general aspect of this gneiss may be expressed by the word gran- 

 itic, because the stratified lines are obscure. Plence it is possible that the 

 formation may be represented in the Whately and Hatfield area of sien- 

 ite, as given in the Massachusetts map. 



HoiiNiu.KNDK Schist. 



Our studies indicate the existence of a narrow band of hornblende 

 schist adjacent to several of the areas of Bethlehem gneiss in the Con- 

 necticut valley. Allusion has been made to the positions of several of 

 them, upon page 367, and others will be described in the following 



