181 
one well-marked joint-plane sloping steeply to the south; and 
the southern sides of all three of the holes have, apparently, 
been carried away, by the removal of a single large joint-block 
of the granite. Since this block appears to have been torn 
away bodily, leaving an angular, unglaciated surface, and no 
trace of the block itself can be seen in the vicinity, we may 
fairly regard its removal as the last work accomplished by the 
ice-sheet on the lee side of this ledge. 
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Fic. 22—PorHoLE, CooPER's ISLAND. 
The fourth pothole is or was the largest of all, and hence 
has been commonly called the Well." Passing over the rocky 
n 
elevation in a northerly direction, it may be found about a 
