LARAMIE REGION, WYOMING 443 
Pleistocene period. It is probably safe then to consider these canyons 
as of Pleistocene age. 
Absence of glaciation.—The Laramie Range was too low to generate 
glaciers during the Quaternary period. The evidence of this is both 
positive and negative. ‘The topography is entirely such as is produced 
by the action of running water and wind, and the thin residual soils 
have been in no wise disturbed. On the other hand, there is an entire 
lack of glacial drift in the district. The same is. true of the greater 
part of the Medicine Bow plateau, although the highest range of these 
mountains—locally known as the “Snowy Range’’—shows, even at 
a distance of forty miles, the characteristic sharp peaks and cirques 
produced by Alpine glaciers, and some of the tongues of ice 
ran far down their individual valleys. Judging from the Bighorn 
Range farther north, an elevation of more than ten thousand feet 
would have been necessary to induce glaciation in this latitude 
and climate. 
Modification of the topography by wind.—Here, as in most parts 
of the dry West, the wind has been an agent of great importance. 
Mushroom monuments and other wind-carved forms are widely 
distributed. The many shallow hollows—some containing ponds— 
which are characteristic of the region, seem to be explainable only as 
the work of the wind. They appear in all sizes, from little saucer- 
like depressions to such features as the “ Big Hollow” west of Laramie 
which is nine miles long and 150 feet deep. They are independent 
both of the kind of rock and the elevation, being found as well in the 
granite on the Sherman plateau as in the present flood plain of the 
Laramie River. ‘These land forms, the stony flats strewn with pol- 
ished bits of flint and honeycombed limestone, and many other sig- 
nificant things, testify to the efficiency of wind erosion in the Laramie 
region. The depositional phase of wind-work has not, however, 
impressed itself perceptibly on the topography. The abraded 
material has been largely exported. 
Summary and conclusions.—Briefly stated, the more important 
points in the later history of the Laramie region, as interpreted in 
this paper, are these: 
1. The district was completely buried beneath the horizontal beds 
of Cretaceous sediments. 
