The. Evohitio7i of Climates. — Manson. 207 
To the east lies that remarkable and interesting feature, 
the "unglaciated area." In this area are the "bad lands" of 
Dakota, full of beds of Tertiary fossils in a perfect state of pre- 
servation. Glacier ice has never invaded this area, for not only 
are the most delicate fossils left untouched near the surface of 
the softest rocks, but every topographical feature is marked 
only by the denuding agency of water. The topography is 
marked and peculiar ; whilst denuding agencies have been act- 
ive at all times since the Tertiary — never has the grinding, mov- 
ing glacier shaped the blufTs into rounded hills nor filled the 
valleys with gravels, sands and clays. On all sides except the 
western lava border, the mighty tread of the glacier has ground 
down and buried every pre-glacial feature. The great chain of 
moraines, erratic blocks, kames and kettle holes which traverse 
the continent skirts its northern border, but before turning 
south, retreats easterly for 8°, and then practically follows the 
course of the Missouri river southeast to latitude 37°, near the 
mouth of the Ohio; there it turns to the northeast and crosses 
the rest of the continent to cape Cod in 42° north. Within 
the limits of the area thus enclosed on the north and east bv 
evidences of vast glacial action, and on the west by the great 
lava plain the gentler forces of water and air have alone shaped 
the topography; and within its borders are found abundant 
stores of fossil Tertiary life. These forms afiford the links be- 
tween the life of earlier and that of succeeding ages. 
Although snow now covers the whole area in w^inter never 
did it accumulate so as to mould the rounded hills and slopes 
which are so characteristic of glaciated countries; and although 
the winter temperatures fall far below zero Fahr. the summers 
are warm and frequently characterized by intensely hot pe- 
riods. 
Whilst glacial denudation and markings are thus wanting 
there is no evidence to show that since the Tertiary, the 
streams have ever ceased to carve their vertical walls and to fill 
the valleys below with water borne sediments. 
That this area should have escaped glaciation by reason of 
less elevation is not tenable for more southerly areas towards 
which both glacier ice and water flowed were deeply glaciated. 
That it should have escaped glaciation by reason of less pre- 
