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Mesozoic and Cenozoic Geology and Paleontology. 209 
terrace of table land, the ancient shore of a great body of water, that 
once filled the whole of the Red river valley. It is only 210 feet above 
the level of the surrounding prairie, or between 900 and 1,000 feet 
above the ocean level. High above Pembina mountain the steps and 
plateaux of the Riding and Duck mountains arise in well defined suc- 
cession. On the southern and southwestern slopes of these ranges the 
terraces are distinctly defined, on the northeast and north sides the 
Riding and Duck mountains present a precipitous escarpment which 
is elevated fully 1,000 feet above Lake Winnipeg, or more than 1,600 
feet above the sea. One of the terraces here is 1,428 feet above the 
level of the ocean. The denudation of the Cretaceous, in the valley of 
Lake Winnipeg, has been enormous, because the shales crop out 500 
feet above Dauphin lake, where their position is nearly horizontal, and 
evincing their former extension to the northeast, if not as far as the 
north shore of Lake Winnipeg. Sand hills and dunes occur on the 
Assiniboine, Qu’ Appelle, South Branch, and north of Touchwood hills. 
Prof. E. W. Hilgard+ described the drift (he called it the Orange 
Sand formation) as covering the greater part of the State of Missis- 
sippi. It is overlaid by the Bluff Group, and is not, therefore. 
above Natchez, exposed ou the surface, within eight to twelve miles of 
the Mississippi river ; below Natchez, however, it forms the White 
cliffs on the Mississippi itself. It does not cover the northeastern 
part of the State, and is absent from other limited patches. The 
thickness is quite variable, sometimes reaching 200 feet, though 
usually not more than 40 to 60 feet. The material is usually silicious 
sand, colored more or less with hydrated peroxide of iron, or orange- 
yellow ochre. Sometimes pebbles or shingle, either cemented into 
puddingstone, or more frequently loose and commingled with sand or 
elay occur, and at other times limited deposits of clay are found. It 
contains fossils from the Silurian, Devonian, Carboniferous, and Cre- 
taceous formations which are exposed to the north in Tennessee, Ken- 
tucky, Indiana, Illinois and Ohio, and silicified wood from the lignite 
strata of Mississippi. The character ofthe surface upon which it rests 
its own irregular stratification, and the dependence, to 2 great extent, 
of the nature of its materials, upon that of the underlying formations, 
proves, beyond question, that its deposition, preceded and accompanied 
by extensive denudations, has taken place in flowing water, the effect 
of whose waves, eddies and counter currents, is plainly recognizable in 
numerous profiles. Nor can there be any doubt that the general direc- 
* Geo. Sur. of Miss. 
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