
GLACIAL PHENOMENA AND SUPERFICIAL DEPOSITS. 251 
578. The deposit of the Red River Valley, compares closely with the 
loess of the Rhine, and with the alluvial deposits which occur on the Mis- 
souri River and its branches, as high up as Ft. Pierre. The valley of the 
Missouri, like that of the Red River, appears to be floored by a very fine 
deposit, from beneath which as the ground rises at the sides, the stony 
material of the drift emerges. The term yellow marl, has been applied to 
these light-coloured alluvial beds, but some confusion has arisen from the 
use of the same name, to designate similar but coarser deposits, of the 
surrounding highlands, which belong properly to the glacial drift. The 
yellow marl deposits of the vallies, and the light coloured marly drifts 
from which much of their material has been derived, are alike character- 
ized by their extremely favourable influence on the overlying soil; and 
all who have studied the agricultural resources of the Western States and 
territories, concur in attributing the inexhaustable fertility of the soils 
of the lower level prairies, to the wide distribution of this marly material. 
579. South of the Line, the pale marly drift seems to extend on the 
Missouri as far west as the great bend, and southward to cover the 
entire eastern part of Nebraska. It would appear to be limited 
westward, by the gradually increasing elevation of the prairie, in that 
direction, and to spread out in a _ fan-shaped form, from the 
southern end of the great -north and south depression, which the Red 
River Valley in part occupies. It is, no doubt, connected with the 
northern drift, and by description agrees exactly with the pale-coloured 
and marly drifts developed in British America, from the edge of the 
Pembina Escarpment westward to the foot of the Missouri Coteau, thus 
occupying the whole of the second great prairie steppe. 
580. The similarity of the yellow marly alluvium of the Missouri 
and Red River vallies, is not one of chance merely, nor to be accounted 
for altogether by the resemblance of the glacial drift from which much 
of the material has been derived. The trough of the Red River Valley is 
continuous beyond the source of the river, and passing southward from 
Traverse Lake, from which the river rises, it still preserves its 
character and direction, and in about six miles, Big Stone Lake, the 
waters of which empty into the Mississippi River, is attained. In thus 
passing over the watershed between Hudson Bay and the Gulf of Mexico, 
the elevation is found to be at no point greater than from 960 to 970 feet 
above the sea. The figures are from Prof. Thomas’ report; who has 
drawn attention to the importance of this remarkable physical feature.* 
* U.S. Geol, Surv. Territ., 1872, p. 291. 
