212 GEOLOGY OF OLD HAMPSHIKE COUNTY, MA8S. 



4. The Pelhani-Shute.sbui-}- syncline. 



5. The great central syncline. 



6. The eastern syncline. 



7. The zone of contact and disturbance around the Belchertown tonalite. 



8. The Wilbrahani syncline. 



9. The Monson syncline. 



10. The East Greenwich-Enfield syncline. 



THE NORTHFIELD SEMISYNCLIIfE. 



For a long- time it seemed to me probable that the rocks at the mouth 

 of Millers River (see p. 295) and those here under discussion were a con- 

 tinuation of the Beruardston series, and thus of known age; and because 

 of the importance of the question I have studied these areas with great 

 care and describe them in somewhat greater detail than usual, and com- 

 pare them with the Bemardston series, in order that the grounds for 

 accepting or rejecting the correlation suggested above may be clearly 

 seen. The fold here described lies along the east line of Northfield, in 

 the Warwick (juadrangle. 



The comparison of this series with the Silurian beds west of the river 

 forms the first step in the correlation of the beds east and west of the river. 

 The gneiss a in the sections below (p. 213) is identical with the Becket 

 gneiss. The beds h and c are close lithological representatives of the 

 Rowe schist. The bed d agrees well with the (Jhester amphibolite. The 

 whetstone-schist e is closely like the Savoy quartzose schist, while the 

 bed / is the exact counterpart of the Conway schist in all its peculiarities, 

 even to the presence of spodumene and cleavelandite dikes. 



GENERAL DESCRIPTION. 



The rocks were first compressed into a great syncline in the Monson 

 gneiss, the axis of the syncline pitching to the north, and then a north-south 

 fault occurred along this axis, and the rocks on the east were upheaved by 

 about the thickness of the series (1,890 feet), and so far eroded that only 

 a remnant of the lowest bed remains on the eastern half Then several 

 transverse faults cut across the beds, and one is notable from the amount 

 of drag which the beds on the north side of it have sufl:ered at their south 



