10& Geology ofDeerJield, S/-e. 



alternating with mica slate, siliceous slate, or chlorite slate. 

 It is thus coloured to show the extent of the argillite, and not 

 from a belief that this rock is of the transition class ; for in 

 this region the argillite is undoubtedly primitive. Some quar- 

 ries of this rock have been opened in Massachusetts ; and in 

 Vermont are extensively wrought. I have not learnt how far 

 the argillite extends northward in Vermont and New-Hamp- 

 shire. Its strata are almost perpendicular, inclining a few de- 

 grees to the west. 



The primitive region on the west side of Connecticut river, 

 included by the map, is made up of mica slate, as a prevailing 

 rock, particularly in the northern part. Hornblende slate 

 sometimes alternates with this, and sienite appears in various 

 places, though its strata are generally thin. Limestone also 

 occurs in Deerfield, Conway, Colrain, &c. of a dull browa 

 colour. It contains so large a proportion of silex that it is 

 often but little removed from granular quartz. Lime for 

 building has sometimes been obtained from it. A range of 

 granite, containing veins of lead ore, appears at Southampton, 

 and proceeds to Hatfield. North of this, the other rocks 

 cover it, and it does not again rise within the limits of the map. 



Sienite is the prevailing rock on the east side of Connecti- 

 cut river in the primitive region, more particularly in the 

 southern part. In some places a narrow stratum of mica slate 

 lies next to the conglomerate of the secondary formation, and a 

 low range of graphic and common granite has been observed 

 in Amherst and Leverett, lying next to tlie mica slate. Other 

 veins of granite aleo traverse the sienite ; and gneiss occurs in 

 many places. The proportion of hornblende in the sienite 

 is generally small, and mica is often present in considerable 

 proportion. Porphyritic sienite is common in this quarter, and 

 steatite occurs in its eastern part. 



Most of the primitive region on the map is broken and 

 mountainous, being made up of parallel ridges and detached 

 eminences. The strata run nearly north and south, and dip 

 to the east at angles between 20° and 60°. It would be easy 

 to extend the map on the west to the top of Hoosack mountain, 

 ji^ince the country is all primitive ; aad on the east the primi* 



