16 GUIDEBOOK OF THE WESTERN UNITED STATES. 
large glacier, the western ice sheet, invaded Minnesota from the north- 
west and spread a mantle of gray drift over part of the area already 
covered by red drift. The boundary between these two drift sheets 
passes through St. Paul but is not a sharp line of separation. 
When the front of the western ice sheet rested on the hills about 
St. Paul streams of water issued from the ice and carried with them 
vast quantities of sand and gravel, which they deposited beyond the 
ice front. One of these streams left the ice mass in the vicinity of 
Minneapolis and spread a great sheet of sand and gravel over the 
country upon which St. Paul has been built. It is mainly these ~~ 
outwash materials that can be seen from the Northern Pacific trains | 
as they pass from St. Paul to Minneapolis. The gravel was deposited —_ 
irregularly and now forms knobs that are separated by kettle-like | 
4 
ee Me st ee OT 
depressions. Lake Como, on the right (north)! of the railway, lies 
in a basin of this character. 
Descending somewhat from the high land the railway crosses the y 
gorge or canyon cut by Mississippi River in the Platteville limestone 
and St. Peter sandstone. These rocks were formerly well exposed : 
here, but they have been obscured by the construction of mills and = 
the slumping in of soil from the top of the bluffs. While crossing - 
the river the traveler can see on the right what remains of the Falls 
of St. Anthony, after a large part of the water has been diverted for 
the development of power. Further erosion of the rock has been 
prevented by the building of a low dam at the crest of the fall, and 
about 35,000 horsepower has been generated for running the great 
flour mills that line the river bank for some distance. 
On the left are the buildings of the University of Minnesota, 
which occupy a commanding position on the east side of the river. 
The rocks rise toward the north, as shown by fig- 
Minneapolis. ure 2 (p. 17), even more steeply than the grade of | 
Elevation 854 feet. the stream, and the top of the St. Peter sandstone 
So Patiomke: nd the overlying Platteville limestone appear higher 
in the canyon wall than they do at Fort Snelling. 
Immediately after crossing the river the train entersthe UnionStation 
at Minneapolis, to receive other travelers bound for the far West. a 
North of Minneapolis the railway again crosses Mississippi River, 
but here there is no gorge, the river flowing in a shallow valley in : 
the drift-covered pla*  ,, ust beyond Northtown, on the right (east), 
the St. Peter sandstone is visible for the last time. This outcrop 
lies at considerably higher level than any outcrop of the sandstone 
in the gorge below the Falls of St. Anthony, indicating that the 
beds of rock rise northward more steeply than the surface of the 
Sa 
oo eae ies! 4 re See te 
Pe Se eee eee SD Teta Gece bet, Bie caee A ay See 
! The terms right and left refer to the westbound journey. - 
* The figures giving distance from St. Paul are taken from the Northern Pacific 
Railway folder of 1915, 
EAN a nah te 
cs 
