GLACIATION OF THE ALASKA RANGE 4209 
headward ends of all the important valleys (see Plate I). In 
describing these glaciers Moffitt says: 
The most conspicuous of these glaciers are Gulkana Glacier, the glacier in 
which Eureka Creek and East Fork of Maclaren River head, Maclaren Glacier, 
and the two large glaciers at the head of Susitna River. The last two are 
much larger than any others in this region. They are fed by the snow fields 
in the high rugged country south of Mount Hayes and Cathedral Mountain 
and are the principal sources of the Susitna, although the glaciers to the east 
also contribute much water. The westernmost of the two large glaciers is 
about 25 miles long and more than 13 miles wide throughout its whole length- 
The eastern glacier is about 2 miles wide, but is not so long as the first. Mac- 
laren River Glacier is much smaller than either of these, being a little more 
than 1o miles long and not more than a mile wide at its lower end. Gulkana 
Glacier and Cantwell Glacier (10 miles northwest of the westernmost Susitna- 
Glacier) are remarkable . . . . in that they contribute water to both Bering 
Sea and Pacific Ocean drainage. 
Most of these glaciers appear to be retreating. ‘Their surfaces are smooth, 
they end in smooth slopes rather than ice cliffs, and most of them show by the 
position of terminal moraines that they have receded considerably in recent 
times. 
The peculiar drainage mentioned by Moffit deserves a further 
word of description. Three glaciers on the south side of the range, 
namely, Cantwell Glacier, the glacier at the head of Eureka Creek, 
and that one in which Gulkana River heads, all contribute water to 
two separate great drainage basins. The obvious outlet for the 
waters from all these glaciers is to the south, for the distance to the 
sea is shortest in that direction, and a high mountain range must 
be crossed by any northward-flowing streams. No detailed studies 
have been made at any of these places, but in each of the three 
cases the controlling conditions were probably much the same. 
The greater accumulation of glaciers on the south side of the range, 
at the time of the maximum glaciation, filled both Copper River 
and Susitna basins with ice to a great thickness, as has already been 
stated. This ice body found such outlets as were available and 
at least two tongues pushed northward across the Alaska Range 
through what are now Broad and Delta passes. These outlets 
of escape were probably determined by low divides created by the 
«F, H. Moffit, ‘“Headwater Regions of Gulkana and Susitna Rivers, Alaska,’ 
Bull. U.S. Geol. Survey No. 498, 1912, p. 53. 
