

GLACIAL PHENOMENA AND SUPERFICIAL DEPOSITS. 227 
them is found to be very largely composed of their soft debris. At one 
place about three miles west of the former position of Wood End Depot, 
a scarped bank of the stream, about fifty feet in height, is seen to be en- 
tirely composed of drift ; which is a yellowish sandy and gravelly deposit, 
hard enough to stand in perpendicular-faced banks, and in a general way 
much resembling that already described at Long River and elsewhere. 
The boulders are of Laurentian and Limestone, with a good many belong- 
ing to the Quartzite drift, and fragments of local sandstones. Many of the 
boulders and pebbles are polished flat, on one or more faces, and scored 
with glacial markings. Agates and fragments of silicified wood, though 
not actually observed imbedded in it, must also occur in the drift of this 
vicinity, as they are not unfrequently found in pebble beds formed from 
its re-arrangement. The agates were here found more abundantly than 
elsewhere, but were not in any locality observed in the parent rock, 
though they no doubt occur in some of the Tertiary or Cretaceous beds 
of the region. They do not usually show conspicuous banding, but are 
semi-transparent and of a pale yellow colour. ) 
Margin and Eastern Region of the Third Prairie Plateau to Wood 
Mountain. 
521. The localities so far described, may be considered as belonging 
to the second prairie steppe, and illustrating the nature of the drift of 
that level. Westward from this point, the country though belonging in 
the main to the third or highest prairie level, is much more diversified, 
and to understand the arrangement of the deposits of the glacial period, 
it is necessary to bear in mind its general contour, of which an outline 
has already been given in treating of the watershed which runs through 
it to the Rocky Mountains (§ 9 et seq.) 
522, One hundred and twenty miles west of Turtle Mountain, the 
second prairie plateau comes to an end against the foot of the great belt 
of drift deposits, known as the Missouri Coteau. Beyond this point, 
three diverse zones of country cross the forty-ninth parallel in the order 
subjoined. 
1. Tumultuously hilly country based on a great thickness of drift, and 
forming the Coteau de Missouri, properly so called. | 
. Flat topped Watershed Plateau, formed of rocks of the Lignite 
Tertiary, and’constituting a part of the First Transverse Watershed 
already described. 
. Lower broken down region south of the Plateau, partly based on the 
bo 
