794 WALLACE W. ATWOOD 
contain ice. Three of the basins below 10,000 feet contained ice 
during the earlier epoch, but not during the later, indicating that, in 
general, a greater elevation was necessary for the formation of gla- 
ciers during the later than during the earlier epoch. 
The glaciers extended southward and northward from the main 
crest-line, reaching their greatest lengths in the central portion of 
the area and decreasing in length both to the east and west, thus 
exhibiting a dimensional symmetry appropriate to the form of the 
range (see Fig. 1). The longest glacier was 27.5 miles in length; 
the shortest independent glacier was 1.5 miles long. During the 
earlier epoch there were thirty distinct glaciers. Most of these thirty 
glaciers may more properly be referred to as great systems, for in 
most cases they were formed by the union of from two to eight yla- 
ciers. During the later epoch, when the ice was not so extensive, 
fewer glaciers united, especially on the north slope, and therefore 
there was a larger number of distinct termini to the ice. The total 
number of independent glaciers during the later epoch was thirty- 
nine. 
If the great systems of the earlier glaciers be subdivided and the 
tributary glaciers be counted as independent glaciers, there were: 
8 glaciers 20 miles or over in length 
ors anne 15 to 20 miles in length 
9 (73 Io to 15 (73 66 (79 
2I ce 5 to Io (73 (73 (73 
63 (79 I to 5 (73 be (73 
or a total of 104 glaciers over 1 mile in length. 
COMPARISON OF THE GLACIATION OF THE NORTH AND SOUTH 
SLOPES 
The lengths of the glaciers on the north and south slopes were, on 
the average, during the earlier epoch, about ten and sixteen miles, 
respectively. During the later epoch the lengths of the glaciers on 
the north and south slopes were about eight and ten miles, respect- 
ively. There were but two glaciers on the north slope that reached 
twenty miles in length, while on the south slope there were six that 
exceeded that length. The lower limits of glaciation on the two 
slopes are shown in the following table: 
