Hunt.] 508 [April 21, 



highest mountains of Massachusetts in the northwesterly portion of 

 her territory, and in leaving the broadest extent of lowlands in the 

 southeastern part. 



The parallelism of feature lines, which is so characteristic of the 

 Appalachians, is so decidedly marked in the general course of the 

 physical regions and of the ranges of hills, as to show an iutimate 

 correspondence with and dependence upon the structure and plan of 

 this mountain system. Even in the eastern region, the one most re- 

 moved from the axis of the system, the range of low hills which 

 skirts the tide- water region from the Charles River to Salem and con- 

 tinues to the extremity of Cape Ann, is, throughout, parallel to the 

 more central mountainous regions west and north of it. There are 

 ranges, however, which are not strictly conformable, in their courses, 

 to the principal ones. We have an example of these in the east and 

 west ridges of the vicinity of Boston, and in the hills of Quincy and 

 Milton. The trend of these so closely corresponds with the strike of 

 the rocks, as to show that their courses are determined by proceses 

 of elevation rather than by erosion. 



From these, and other similar data, it is argued that the general 

 character of the most conspicuous features, seen in the configuration 

 of the State, is derived from their inseparable dependence upon the 

 structural plan of the Appalachian mountain system; that other 

 features of secondary importance have arisen from minor systems of 

 elevation, which, although associated with, do not appear to have 

 been essential parts of the more general one, and that the different 

 meteoric agents have modified these without obliterating them, and 

 have added others, which, without wholly obscuring the plan, have 

 increased the diversity and complication of the topography of Mas- 

 sachusetts. 



A discussion of some points touched upon in the commu- 

 nication of Prof. Niles followed, being carried on principally 

 by Dr. Hunt, Prof. Hitchcock and Prof. Shaler. Prof. Shaler 

 alluded to the granitoid character of the rocks at Braintree, 

 to which Prof. Niles referred. Dr. S terry Hunt spoke still 

 further on the same subject. 



The crystalline rock, said Dr. Hunt, seen in contact with the fossil- 

 iferous Lower Cambrian (Menevian) strata of Braintree, Mass., is 

 clearly a variety of the feldspar-porphyry or orthophyre, which is so 



