MODEL OF NEW ENGLAND. 149 



So striking are these features in New England that it 

 would almost appear as if the development of the Sandon 

 and Stannifer Level had been carried on to a certain stage 

 for the sole purpose of leaving the more acid stocks and 

 bosses in striking topographic relief. In fact, a rough 

 geologic map of the acid plutonics and volcanics could be 

 sketched easily on a contour map, the higher portions 

 indicating the positions of the acid rocks. Nevertheless, 

 the various levels are separated from each other by youthful 

 topography, or rather, the Stannifer Level is connected to 

 the higher levels by youthful forms. At one time the 

 writer was led to believe that the scarps and gorges of the 

 higher levels represented the action of erosive activities 

 on fault blocks uplifted in late Tertiary Time above the 

 Stannifer Level, but after careful examination the faulting 

 hypothesis had to be completely abandoned, as there was 

 direct proof to the contrary. On the other hand, differ- 

 ential erosion is sufficient to explain the phenomenon. 

 Nevertheless, the mind is almost overwhelmed in the con- 

 templation of such relative rock strength as is evidenced 

 by the apparent indifference of acid granites and massive 

 rhyolites to erosive activities. If New England had been 

 composed of ordinary claystones, slates, and allied rocks, 

 there would have existed little or no trace of levels older 

 than the Stannifer or Sandon, and the geographer would 

 have had no clue as to the Mesozoic and the earlier Ter- 

 tiary History of New England, except by inference from 

 the sedimentation in adjacent geographic regions. On the 

 other hand, the disposition and extent of these older levels 

 indicate that the periods of time during which the pene- 

 plains under consideration were successively formed in 

 New England became decidedly less and less, while the 

 vertical movements grew more pronounced as the cycles 

 became less in duration. Thus the 4,000-4,300 feet level 

 amounted almost to complete planation, only a few felsite 



