414 THE JOURNAL OF GEOLOGY. 



considered after a general description of the rocks comprising 

 the second or lower division of the Algonkian terranes has been 

 given. 



THE LOWER OR MOUNT HOLLY SERIES OF THE ALGONKIAN. 



In the amphitheatre already described, the rocks of this 

 series occur well-developed in the towns of Mount Holly and 

 Shrewsbury and extend south probably to near the Massachusetts 

 line. They are perhaps no more characteristically developed in 

 Mount Holly than elsewhere to the south, or possibly to the 

 north, but they are best known to me there of anywhere in the 

 State. It seems best, therefore, to designate the rocks of this 

 central area, or core of the Green Mountains, the Mount Holly 

 series. 



In nearly every way the core rocks are contrasted with the 

 Mendon series; these differences will be emphasized below when 

 the question of the relations of the two series will be discussed. 

 A description of the different consecutive members of the series 

 cannot be given, as the rocks are too variable in character, and 

 dynamic action has involved them in such complications. No 

 approach has been made in the determination of the order of 

 their occurences, and it is doubtful if such a sequence will be made 

 for years to come, unless more discriminating criteria are forth- 

 coming. Many unlike members there are, but they are charac- 

 terized by no presistence of horizon, or if they are, metamorphism 

 has obliterated all distinguishing features. The area appears as 

 a multitude of patches of different kinds of rocks, whose rela- 

 tions with one another seem impossible of solution. Unlike the 

 Mendon series, there is no pronounced northerly lamination 

 agreeing in the main with the genuine strike of the stratification. 

 The structure here is in part due to zones of unlike mineralogical 

 composition ; most of the igneous rocks have been well lami- 

 nated and the gneisses and schists have their characteristic 

 arrangement of constituent minerals. 



A detailed description of all the varieties of rock occurring will 

 not be attempted here ; some of the more noteworthy areas will be 



