THE CAVES AND POTHOLES AT ROCKWOOD. 253 



Such an under current getting into a depression in the rock, aided by 

 stones from the glacier would be sure to produce Potholes. This is the 

 origin of those at Lucerne. In such cases you are likely to find, that 

 the stones derived from the glacier that did the work are large, and 

 that the surface of the rock is much abraded illustrating glacial striae 

 very impressively. 



At Rockwood Potholes we so far have not been able to discover 

 glacial markings, and among the rounded stones none exceeding six 

 inches in diameter, and thus are inclined to think these holes have 

 been worked out by the water of a river rather than that found 

 beneath a glacier. However as further information is secured we 

 may be led to modify the conclusions presented to-night. 



