40 
GUIDEBOOK OF THE WESTERN UNITED STATES. 
the old surface of till and outwash gravel is in its original condition, 
not having been smoothed and covered by a coating of mud, as was 
that of the submerged area. 
West of the Herman beach the railway crosses a low, broad ridge 
by a deep cut in glacial tiil and sand. This cut is 4 
Buffalo. 
Elevation 1,226 feet. 
Pop ion 241. 
St. Paul 288 miles. 
miles long, extending as far as the village of Buffalo, 
and it affords excellent exposures of the materials 
transported by the ice. 
Theow ridge through which 
the cut is made is a faint moraine, marking the posi- 
tion of the front of the glacier! that occupied the valley of Red River 
before it became a lake, as described on page 32. 
1 The glacial features of North Dakota 
are the result of the invasion of the ice 
sheet that originated west of Hudson Bay. 
At the time of its greatest expansion this 
glacier _ all of North and South 
t of Missouri River with ice 
Bae pls and AS Se thou- 
ds of feet in thickn 
A study of the materials beak down 
from the north shows that glaciation was 
not confined to a single stage of growth 
and decadence of the ice sheets, but that 
there were several advances and retreats, 
_ and that the amount of movement ac- 
complished in the various stages differed 
greatly. These fluctuations appear to 
- have been due to the fact that at times 
the climate was favorable for the devel- 
opment and advance of the ice, and that 
at other times it was milder and the ice 
wasted away until large tracts previously 
covered were again in condition for the 
return of and vegetable life. 
During the warmer epochs soils were de- 
veloped, and the glacial materials spread 
over the land were sculptured by newly 
drainage systems. The re- 
turn of colder weather and the advance 
of the ice over most of the area previously 
glaciated destroyed many of the new 
surface features and buried the whole 
under a new deposit of drift. 
The extent of the several ice sheets 
which in Dakotas during the 
Wisconsin gs of glaciation is shown on 
pes at mapon sheet 5 (p. ee North- 
ice that 
saci m the direction of pf ectaa 
Sirsooking 4 southwestward and southward 
around the west end of this ice mass came 
another great glacier from the region west 
of Hudson Bay, which divided at the head 
of the Coteau des es (for meaning 
of the word “‘ coteau’’ see p. 45), or just 
south of the South Dakota line, into two 
great lobes, one of which, known as the 
Minnesota Glacier, passed southward up 
the broad valley of Red River and across 
Minnesota into Iowa as far as the present 
city of Des Moines, and the other, known 
as the Dakota Glacier, mey ed down the 
James River valley t read- ° 
ing westward upon the flanks of ae Co- 
teau du Missouri. The farthest extent of 
these lobes is marked by a well- oe bale 
ridge, called the Altamont nior 
I tamont moraine is Manos by 
the Northern Pacific Railway between 
Sterling and Driscoll and from this point 
recedes far to the east, crossing the line 
between North and South Dakota about 
miles east of Missouri River. In 
South gg its outline is somewhat 
showing that small lobes of ice 
a bad: ee here and there far beyond the 
principal mass. In general, however, the 
on the east, and it is probable that the 
front of the ice and its accompanying 
moraine were largely instrumental in de- 
termining the course of that stream. 
The Dakota lobe of the glacier filled 
all the coun i 
the map, nearly to the North Dakota line. 
The marginal deposit indicating the 
first halt in the glacial wasting and re- 
treat is the Gary moraine, which is 
