Tey ges - PROCEEDINGS OF THE CALIFORNIA 
was evidently over this escarpment that the glacier flowed during a long 
time; but as Lake Valley itself became filled with ice, and its glacier reached 
to the height of six or seven hundred feet above the side of the valley at 
Johnson’s Pass, Echo Lake glacier could no longer escape into the valley, 
but was deflected with the vast ice stream from Lake Valley down the valley 
of the American River. In taking this new direction, the bed of the glacier 
was forced up over what had been before its lateral moraine, grinding off the 
angles of the rocks, and filling up the interstices with mountain meal, so that 
the moraine, particularly towards the American Valley, presents a gentle 
slope, with only an occasional boulder visible. The Echo Lake side of the 
embankment is much steeper, and a few feet below its crest has a ridge of 
moraine rocks, with perfectly sharp edges. This ridge is separated from the 
top of the embankment by a shallow depression, a few yards broad. These 
rocks had evidently been deposited on the ridge of mountain meal as lateral 
moraine, after the Lake Valley glacier had retreated below the level of the 
pass so that the Echo Lake glacier could resume its former course. 
On the south side of the head of the pass, a large quantity of moraine matter 
has been deposited from the glacier coming in from the south end of Lake Val- 
ley. Until Lake Valley itself had been filled with ice up to the level of the 
pass, the moraine matter from this glacier would be deposited in the valley; 
but as soon as the ice reached the level of the pass, a large moraine was de- 
posited, extending nearly half a mile across the head of the pass, and then bend- 
ing to the west down the American Valley. This moraine, at the point where 
it leaves the motintain, is apparently about four hundred feet high, and a 
quarter of a mile thick at its base, and is composed of large masses of gran- 
ite, with their edges quite sharp. Even a mile below the head of the pass, 
the moraine is 150 feet high and 400 feet thick, here forming the north wall 
of the basin of Andrean Lake, a small lake about 300 yards long and 250 
broad, situated directly at the foot of the mountain, on the south side of the 
American Valley. The rocks at this part of the moraine are more or less 
rounded, and the interstices filled with the finer detritus. The middle of the 
valley, near its head, and for some distance down, is covered with a thick de- 
posit of mountain meal, interspersed with large boulders, which have evidently 
been glaciated from the northeast. This has been opened to the depth of 
twenty feet without reaching the country rock. It is completely unstratified, 
and contains a few boulders, well rounded, but not very large, at least such 
was the case in a cut and tunnel made in the deposit towards the north side 
of the valley. In making the cut, a layer of gravel was found about eighteen 
inches from the surface; it was about two inches thick, and composed of 
rounded quartzose and other pebbles, and must have been derived from some 
disintegrated conglomerate beds. The only probable source of this thick 
deposit of finer detritus is from the bed of Echo Lakes, and the glaciated 
mountains to the northeast of the lower lake. It is found forming the bed 
of the American Valley for three or four miles from the summit of the pass, 
but beyond this point it gradually disappears, so that, at six miles from the 
summit, it was found extremely difficult to find any dirt to fill into the crev- 
ices between the rocks, when making a road through the valley. 
