282 SURFACE GEOLOGY. 



These animals were not exactly the same with those now living on our 

 coast, corresponding better with those living farther north. The best 

 writers name three different groups for the eastern American coast. 

 The arctic fauna is at present confined to the limits of North Greenland, 

 and about the pole at the isotherm of o° C. This is succeeded by the 

 Labrador or Syrtensian fauna, extending now as far south as to the mouth 

 of the Bay of Fundy. Our present New England or Acadian fauna ex- 

 tends from the southern limit of the Syrtensian to Cape Cod, and also 

 appears in several places above the lower limit of the latter. The lower 

 British Provinces exhibit one or the other of these faunas according to 

 the presence of the polar current or the influence of the Gulf stream. 



The fauna of Portland in the Champlain period corresponded to the 

 Syrtensian, or the colder one. It seems to have extended as far south 

 as Gloucester or Cape Ann. The northern limit of the Acadian fauna 

 during the same period was near Point Shirley, Winthrop, Mass. Thus 

 the glacial cold was sufficient to bring the boreal life two and a half de- 

 grees farther south than it is found at the present day. 



A list of all the Champlain fossils known to occur in New Hampshire 

 has been given upon page 165. The whale's vertebra, cited from Som- 

 ersworth, must be eliminated from the list. An inquiry into its authen- 

 ticity has indicated that the specimen did not come from the locality 

 specified upon the label. 



The Ground Moraine. 



The common masses of drift scattered over the state are known typi- 

 cally as ground moraine, such as is accumulated beneath glacial ice. 

 The Scotch word for the material is till, which is adopted in this report 

 to signify the ordinary unstratified glacial accumulations. For reasons 

 derived from the Manchester exposures, this term is preferred to a com- 

 mon one of boulder clay. The sub-divisions of it have been defined 

 upon page 9. We accept the theory there stated, that the lower till is 

 the proper ground moraine, and the upper ferruginous division is derived 

 from the melting of the ice-sheet. 



Recent studies reveal the existence of curious lenticular-shaped 

 mounds of till, some of quite large dimensions. These proved so inter- 

 esting that Mr. Upham was asked to devote a season in studying them. 



