1881.| The Ancient Glaciers of the Rocky Mountains. 3 
King announced in 1871, there are true glaciers in the Sierra 
Nevada, and Dr. Hayden’s Survey has more recently found 
others among the Wind River range in the Rocky mountains. 
But during glacial times the quantity of snow and ice in some of 
these uplands, was enormous, In the Uintah mountains the traces 
of vanished glaciers are singularly fresh. Beautiful horse-shoe- 
shaped morainal-mounds, occurring far down the valleys, mark 
pauses in this final retreat of the ice. These have been well 
described by Mr. S. F. Emmons and Mr. Clarence King, whose 
narrative I can fully confirm from my own observations. In the 
Wasatch mountains, also, as the same observers have shown, 
some of the principal valleys were occupied by glaciers. I was 
particularly struck by this proof of glaciation in the region of the 
Cottonwood cafions. At the mouth of the gorge of the Little 
Cottonwood stream, a pile of morainal-heaps lies on the edge of 
the highest of the series of ancient terraces of Great Salt lake. 
There can be little doubt that at the time of the greatest exten- 
sion of this sheet of water, when filling the vast basin named 
Lake Bonneville by Mr. Gilbert, it escaped by a northern out- 
flow into the Snake river and the Pacific, glaciers crept down the 
valleys on its eastern side, and in one case, at least, advanced into 
its waters. At this locality the ice descended to within 5000 feet — 
of the present sea level. . 
But the most startling testimony to the size of the western 
glaciers, which I met with in the course of a recent journey 
through these regions, was supplied by the valley of the Yellow- 
stone river. I entered this valley from Fort Ellis, in Montana, a 
little above the first or lowest cafion. One of the earliest objects 
to arrest my attention was a prominent rock, like a cottage, in the 
middle of the alluvial plain. I found it to bea large block of 
granite measuring 18 x 12 x 10 feet, and weighing upwards of © 
one hundred and fifty tons, which with many smaller erratics lay — 
upon rudely crescent-shaped mounds. There could not be the 
smallest doubt that these were moraine-heaps, nor that the gla- 
cier which carried them must have been very much larger than — 
any of which I had seen traces among the Uintah or Wasatch 
mountains. The broad valley is here full of moraine-stuff. How 
much further north the transported material extends, I had no 
opportunity of ascertaining. But as it is still in full force at the 
5000 foot contour line, it evidently descends to a much lower level . 
