86 RECONNAISSANCE IN NORTHERN ALASKA IN 1901. 



ao erratics. The principal surface or front of the moraine, which slopes southward, 

 supports a growth of spruce, some of the trees having :i basal thickness of 1.V feet. 



A few miles above this moraine occurs the last lingering remnant of the John 

 Valley Glacier. It consists of a lone, roughly circular mass of ice about 300 feet in 

 diameter, rising from the middle of the gravel -covered valley flats to a height of CO 

 feet, as shown in PI. XV, -1. At the top the ice terminates in several distinct knob- 

 like prominences, projecting 10 to 20 feet above the main mass. One of these is 

 cylindrical or pipe shaped. The others are crudely pyramidal. The ice is partially 

 tapped and flanked by a deposit of genuine till from one to several feet thick, to 

 whose protection it doubtless in large measure owes its preservation. From three 

 sides small streamlets of light-colored muddy water, arising from the melting of the 

 ice and thickened with glacial rock flour from the till, flow down and deposit their 

 load of fine, argillaceous sediment over the flats around the foot of the mass. This 

 glacial mud is of very light color. It is sticky, and differs decidedly from the present 

 stream deposits of the valley. This ice mass is undoubtedly a remnant of the John 

 Valley Glacier. Its presence at this late date, after apparently all the other glacial ice 

 has disappeared from the surrounding region, together with the rounded topography 

 of the adjacent mountains, already noted (PI. XV, A), suggests that this locality is 

 probably near what was the belt of maximum precipitation, and consequently of 

 maximum ice accumulation, that traversed the mountains during Glacial time, and 

 is therefore among the last to become free from ice. 



In the north slope of Anaktuvuk Pass, between John and Anaktuvuk rivers, the 

 till topography is locally rough and in part terminal morainic. North of Cache Lake 

 it contains occasional stretches of distinctly termino-lateral moraine, trending toward 

 Anaktuvuk River, and for the last 10 or 12 miles of its course, before leaving the 

 mountains, the Anaktuvuk meanders sluggishly through a belt of flats one-half mile or 

 more in width, which lie about 100 feet below the surface of the till sheet or ground 

 moraine on either side. This till sheet, with a slope that rises gently in the main, but 

 which is sometimes terraced, extends from the edge of the flats to the base of the 

 mountains, li miles distant. Near the flats the topography is often of a morainic 

 type, being composed of characteristic hummocks and kettles, and undoubtedly 

 represents a lateral moraine, deposited along the edges of the valley glacier that 

 occupied the flats toward the close of Glacial time. 



The height to which the drift, as a sheet, rises along the northern edge of the 

 mountains away from the Anaktuvuk Valley was not determined. Judging from 

 distant observations, however, it in some cases probably ascends the valleys to S00 

 to 1,000 feet above the general level of the Anaktuvuk Plateau. 



As Anaktuvuk River leaves the mountains its current becomes less sluggish and 

 its channel is soon beset with glacial bowlders. At about 4£ miles from the edge 



