1878.] Geology and Paleontology. 831 
500 wide, with all the elements of atrue glacier. On the east 
base of Fremont’s peak, which is over 14,000 feet high, we dis- 
covered two glaciers, one of which covers an area of one and one- 
fourth square miles, and the other three-fourths of a square mile. 
They were marked by enormous crevasses; also with lateral and 
terminal moraines. We called them Upper and Lower Fremont 
glaciers. These would appear to be only insignificant pora 
of the vast glaciers that must have covered these mountai ur- 
ing the true glacial period. On the west side of the ahe the 
moraines and glaciated rocks are found on a vast scale. On the 
west side of the range, a glacier must formerly have existed, eighty 
miles long and twelve wide, with the arms extending up the gorges 
of the streams to the very water divide. ese glaciers will be 
more fully described in the 12th Annual Report of the U. S. Geo- 
logical Survey.—F/. V. Hayden. 
WasatcH Group.—Along the east side of the Wind River 
mountains and filling up the Upper Wind River valley, is a lee 
thickness of modern Tertiary strata that has been weathered in 
wd remarkable forms, and which are known in the West n 
Lands.” The strata are most beautifully variegated with 
remind one of the Jura-Trias red beds. This formation was de- 
scribed by me in 1859, in detail, and named the Wind kiver 
roup. It covers a broad area in this region, extending from the 
source of Wind river to the Sweet Water mountains, sout 
more than one hundred miles, and west an average width of one 
to five miles. The aggregate thickness of this group cannot be 
less than 5,000 feet. On the west side of the Wind River moun- 
tain, no formations older than the Wasatch group are found. 
This group rests, doubtless, on the Archzean nucleus, inclining at 
the base five to ten degrees. All the older sedimentary rocks 
have been entirely swept away from the granites for a distance of 
one hundred miles, while on the opposite or east side all the cor- 
responding strata are visible from the Silurian to the Cretaceous; 
the Wasatch beds cover a large part of the Green River Valley, 
especially about its sources. 
am convinced, also, that a group of strata which I named in 
so much used in the Reports on Western geology, that it will | - 
probably prevent the use of the former to any extent in the future. 
When the Northwest is more fully explored, it will probably be 
found that the Wasatch group covers a large area extending | 
more or less from our north line far into New Mexico.—/. V. 
Hayden ‘ 
1 See Annual Report, page 177, reprint. 
e 
