In general the valley is V-shaped, but at the head it widens and shows a tendency to assume a more curved, or U-shaped, outline in cross-section, thus suggesting a glacial amphitheater or cirque.
In the winter ice and snow accumulate and have a tendency to move from the dividing ridge down the steep slopes which the rapidly cutting stream has left.
During the spring months, when the ice is softening and melting, the head of the valley is occupied by a veritable though small and transient glacier.
The drainage areas of Sixtymile and Fortymile rivers are separated by a ridge of moderate height, whose top is comparatively flat and forms part of the general plateau in which the streams have excavated their deep valleys in late geological time.
It is on Miller Creek, however, that the richest strike made at the time in the Yukon diggings was that by John Miiller, who cleared from one claim of 500 feet along the bed of the gulch a sum which was variously estimated at $30,000 to $50,000 as the result of the work of two winters and one summer.