620 ALLEN DAVID HOLE 
covered portion occasional accumulations of rounded and sub- 
angular bowlders in variety occur; in the upper portion, each has 
the flattened bottom and receding sides which distinguish glaci- 
ated cirques from the narrow, V-shaped valleys which were 
unoccupied by ice. At about 11,000 feet in elevation in the cirque 
north of Magpie Gulch, the topography is of the irregular form 
which may in part be due to landsliding. Above this, projecting 
points of rock in place show well-rounded forms, though no typical 
roches moutonnées occur. The usual long talus slopes and almost 
perpendicular rock walls form the upper boundary of the cirque. 
Magpie Gulch is quite similar in its general features; it has, how- 
ever, a greater length, and contains a much greater accumulation 
of talus. 
Below the mouth of the stream draining Magpie Gulch, glacial 
drift is present over the greater part of the surface of the valley of 
Bilk Creek and on the edge of the mesas on either side. In the 
lower part, however, for a mile or more above the junction of Bilk 
Creek with the San Miguel River, the drift is not conspicuous; for 
not only are the sides too steep, for the most part, to afford a place- 
for lodgment for débris, but talus slopes at the base of the cliff faces 
have formed in post-glacial time, so that drift which may have been 
left on the less steep slopes nearer the stream has since been effec- 
tually concealed. Farther upstream the valley is broader and the 
products of weathering form alluvial cones and fans, especially on 
the west side of the stream. Beginning at a point about half a mile 
north of parallel 37° 55’ N., and continuing up the valley for four 
miles, glacial débris is in general abundant near the stream. At the 
lowest point in the tract just named, the débris is in the form of 
terraces on the east side of the stream, consisting of unstratified 
drift as far as observed, with bowlders in variety, some of which are 
striated. The terraces distinguished are two in number, their 
surfaces being 20 feet and 4o feet, respectively, above the stream 
Half a mile farther upstream, on the west side, stratified drift is 
exposed 100 to 150 feet above the stream. At elevation 9,000 to 
- 9,100 feet morainal hills 40 feet in height occur on the east side of the 
stream. From this point well-marked morainal deposits, ranging 
up to 75 feet above the bottom of the valley, extend upstream 
