Fic. 20.—TITTLING Rock, COHASSET. 
On the northwest slope of Telegraph Hill, just above the 
junetion of the main hill with the lower, flat-topped part, is a 
block of coarse granite about fifteen feet in diameter and from six 
to seven feet high above the ground. А very similar bloek rests 
in a similar position on the north side of Strawberry Hill. It 
is about fifteen feet square and eight if not ten feet thick. Two 
bowlders of granite, essentially similar to these, are similarly 
situated on the northern slope of Otis Hill, in Hingham. The 
occurrence of these isolated blocks on the northern aspects of 
the hills, and at approximately the height of one of the principal 
sand plains, is certainly suggestive of their transportation by 
floating ice rather than the ice-sheet ; and it appears necessary 
to regard them as having been derived from the granite ledges 
north of the Boston Basin, the nearest possible source of granite 
of this character, in the direction of glacial movement, being 
twelve to fifteen miles distant. 
GLACIAL POTHOLES. 
Four years ago, my attention was first called by Mr. T. T. 
Bouvé to the existence of a fine series of glacial potholes 
on Cooper’s Island in Little Harbor, Cohasset, and I had the 
