270 



movement over the harbor area is proved, also, by a 

 corresponding variation in the striae observable sometimes 

 on tlie same ledge and often on adjacent ledges ; and the fact 

 that the later striae have been superimposed upon the earlier, 

 witiiout entirely obliterating the latter, testifies to the feebly 

 erosive character of the later movement. 



Directions of Glacial Striae. 



Grape Island, on slate , . . . . S. 60° E. 



Unit's Cove, on a dike S. 40° E. 



Planter's Fields, on slate S. 25° E. 



Beal Street, on coarse conglomerate S. 23°-25° E. 



" melapliyr ^. S. 32°-35° E. 



Seal's Cove, on slate S. 30°-35o E. 



West Hingham (Fort Hill), on diorite S. 25°-35° E. 



(near the Station), on melaphjT . . S. 23°-25° E. 



Weir River Street, on granite S. 23°-26° E. 



Corner Union Street and Long Bridge Lane, on granite S. 22°-25° E. 



Lazell Street, 1,000 feet south of Free Street . . S. 23°-25° E. 



Rockland Street, corner of Summer Street . . . S. 25°-30° E. 



Granite quarry near Abington Street S. 25° E. 



The fragments of marine shells forming an integral part of 

 the till in several of the Nantasket drumlins and testifying to 

 the preglacial existence of Boston Harbor, appear, so far, to 

 be wholly wanting in the Hingham drumlins. This negative 

 evidence is probably, however, of little value ; for the discovery 

 of the shells has been found to require, in every instance, a 

 deep fresh section of the till, the shells having been removed 

 by solution from the superficial portion of the till. Such a 

 section is afforded by only one drumlin in Hingham — Crow 

 Point Hill. On the north side, this drumlin is exposed to 

 several miles of open water ; and the waves have cut away, 

 as the map shows, at least one fourth of the Avhole mass, 

 forming a fresh scarp from 30 to 40 feet in height. A 

 careful examination of this section on several difterent occasions 

 has failed to reveal the slightest trace of enclosed or preglacial 



