﻿SHORES OF LAKE SUPERIOR. 57 



flowers of a few Saxifrages and Uvularios, gave the 

 only promises of spring. 



In various parts of the lake, the gorges lying be- 

 tween the jutting bluffs of granite or slate are filled 

 with deposits of sand rising in four or five succes- 

 sive terraces to the height of more than a hundred 

 feet above the present surface of the water. Mr. 

 Logan has measured some of the most remarkable, 

 and Professor Agassiz devotes an interesting chapter 

 to the discussion of their origin ; in which he comes 

 to the conclusion that they were formed by the 

 waters of the lake itself, and have been raised, at 

 various intervals, from the beach to their present 

 levels, by the agency of the innumerable trap dikes, 

 which cross the rocks in many directions. 



Near Cape Choyye, on the south side of Michi- 

 picoten Bay, a small gorge between two points of 

 granite is filled, to the height of twenty-five feet 

 above the water, with rolled stones and pebbles. 

 These rounded stones vary in size from that of a 

 hogshead to a hen's egg^ and form a steeply shelv- 

 ing beach, with a flat terraced summit, the larger 

 boulders being next the water, and the smaller 

 pebbles highest up. As the cove is sheltered from 

 high waves, the terrace could not be thrown up by 

 the waters of the lake standing at their present 

 height ; nor can it be owing to the pressure of ice, 

 since that would not graduate the pebbles. 



