SS RECONNAISSANCE IN NORTHERN ALASKA IN 1901. 



if by ice action, but the evidence as to the agency is Dot conclusive. On descending 

 the slope northwestward, however, toward the Anaktuvuk, erratics of the Stuver 

 conglomerate were found at an elevation of about 1,650 foot. The surface in this 



locality, however, is so densely covered with moss that drift may extend above this 

 elevation and yet not be exposed. But on the whole, from this point northward, the 

 till seems rapidly to become restricted to the lower side slopes of the valley, where 

 it forms low bluffs and terraces. 



About 14 miles below Willow Creek, near camp August 5, bluffs of probable 

 till, resting against the bed-rock sides of the valley, rise to a height of 125 feet 

 above the valley flats, and there, apparently as a thin veneer, the deposit over- 

 spreads the adjacent bed-rock bench. This bench is half a mile or more in width, 

 nearly flat topped, and densely covered with vegetation, so that away from its 

 river edge no satisfactory examination of the deposit could be made. A few 

 hundred feet above the upper or distal edge of the bench, however, are outcrops 

 of sandstone, presenting no drift or indication of ice action. 



Twelve miles north of the above locality, about five miles above the mouth of 

 Tuluga River (see PI. XII, A), a similar bench, lying at 100 feet above the river, is 

 capped by a deposit of gravel and sand 20 feet in thickness. Some of the pebbles 

 approach the size of bowlderets, and even bowlders. Though they are waterworn, 

 no stratification is apparent in the deposit, which has much the aspect of a sandy till. 

 Its position suggests that it may have been deposited here by waters from the glacier 

 that possibly occupied the valley at this point. The deposit niay, however, be 

 fluviatile. 



Sixteen miles farther down the Anaktuvuk, about 10 miles above its mouth, the 

 bluff on the left is again capped by from 10 to 40 feet of sand and gravel, in which 

 the gravel is more distinctly washed and rounded than in the deposit above noted, 

 but the absence of stratification and the character of the material again suggest that 

 glacial waters may possibly have been an agency in its deposition. If this inference 

 is correct, the ice stream which occupied the Anaktuvuk valley must have extended 

 down nearly to this point. There is, however, no reason to suppose that it extended 

 below it. On the adjacent part of Colville River there seems to be no evidence of 

 glaciation within a score or more miles above the mouth of the Anaktuvuk. The 

 drainage of this section of the Colville does not seem to have been interrupted since 

 the Tertiary. 



From the conditions above described it is concluded that in the region of the 

 Anaktuvuk Valley, in that portion of the Colville Basin embraced by the curving 

 front of the Endicott Mountains, an ice sheet in the form of a small regional or pied- 

 mont glacier, gradually thinning out toward the north, extended from the front of 

 the' range northward across the inner part of the Anaktuvuk Plateau to the region of 

 Willow Creek, a distance of 30 or more miles. Beyond this point ice flowage seems 



