58 History of Hingham. 



it closes, leaving only upon the surface of the glacier a mark show- 

 ing where it had once been. Subsequently, a new one is formed 

 just where in relation to the land at the margin of the glacier, 

 the former one existed ; and the waters of the succeeding sum- 

 mer again descend upon the rock surface near where they before 

 fell, but not often, probably, in exactly the same place ; and thus 

 other pot-holes are formed contiguous to those of a preceding sea- 

 son, and yet far enough distant to make it evident that they were 

 not produced by the same flow of water. 



Respecting the formation of the crevasses in about the same 

 places on the ice-sheet, there can be no question but that this is 

 due to the irregularities of the subglacial surface ; and as high 

 ridges transverse to the direction of the glacial flow must favor 

 their formation, it is no wonder that pot-holes are often found in 

 the slopes of such ridges and at their bases, as in the case of those 

 described at Cohasset. 



Though lenticular hills, strise upon the rocks, and pot-holes 

 have been described as phenomena of the Glacial Period, it may 

 be well to add that both pot-holes and striae upon rocks may in 

 some instances have been formed in the Champlain Period, now 

 to be presented. 



CHAMPLAIN PERIOD. 



The early part of the Champlain Period was characterized by the 

 final melting away of the glacier. The phenomena attendant up- 

 on the great and long continued flooding over the ice-sheet and 

 over the surface of the land were of marked character. Un- 

 doubtedly, there is to be ascribed to it the formation of the ridges 

 and hillocks called Kames, and the singular hollows in the lands 

 contiguous to these, known as " kettle-holes." Of these some ac- 

 count will now be given. 



KAMES. 



There are found extensively over New England as well as in 

 other regions where the great ice-sheet covered the surface, ridges 

 of a peculiar character, which ordinarily run in a direction some- 

 what approximate to that of the principal stria? on the rock sur- 

 faces northwest and southeast. That is to say, the general direc- 

 tion is this, but the variations are common, and often so like those 

 of a stream of water in its course as to have suggested that the 

 many rivers pouring over the glacial sheet during the prolonged 

 period of its subsidence, cutting into its surface and receiving 

 from it a large portion of its burden of rocky, gravelly, and sandy 

 material, somehow led to the formation of these singular eleva- 

 tions which have long excited the interest of beholders. The 

 view is a reasonable one, and if such was the origin of the kames 

 referred to, their general direction and sinuous course is readily 



