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C. A. White on the Geology of Southwestern Iowa. 29 
exposure in that direction is near Crescent City, a few miles 
above Council Bluffs, and is referred to about the horizon of 
No. 13 of the same section. Thus it will be seen that the line 
of strike is practically east and west between Madison county 
and the Missouri river. 
It was remarked that the fall of Grand river is a little greater 
than the southerly dip of the strata over which it passes, so 
that one finds lower beds exposed as he goes down the stream. 
This would be expected from the fact that the stream bears a 
little to the eastward, obliquely across a slight westerly as well 
as southerly dip; but the fall of all those streams between that, 
and the Nishnabotany river, is almost exactly coincident with 
the dip of the strata, wherever they have cut their valle 
through the heavy drift deposit. This is clearly seen along the 
Yodaway river, where the bed of coal of the horizon before refer- 
red to, reaches its greatest development, and is found a little 
above the water at intervals, from the northern part of Adams 
county, to a point a few miles within the state of Missouri. 
The impure limestones associated with the coal bed, along the 
course of this river and its branches contain, both above and be- 
low the coal, but more especially below it, very many species 
fossils identical with those at the locality on Grand river just re- 
ferred to, and also with those at Nebraska City, which Dr. Geinitz 
and Prof. Marcou refer to the Permian period. (loc. cit.) 
No other rocks except those of this horizon appear along the 
Nodaway, but the Tarkeo has bared the equivalent of No. 15 
of the previous section, in the northern part of Page county, as 
has also the East Nishnabotaty, in Montgomery county. The 
lower part of the carbo-argillaceous horizon is occasionally seen 
in the valley slopes of those two streams, but its bed of coal is 
not seen west of the Nodaway, until the bluffs of the Missouri 
river are reached in the northwestern part of Fremont county, 
at the locality before mentioned, where the coal has diminished 
in thickness to six inches. e same bed of coal also dimin- 
ishes in thickness as one goes down the Nodaway, being found 
only ten inches thick just within the state of Missouri; and to 
the eastward it thins out entirely before reaching Grand, or 
Middle river. 
The following section was measured in Fremont county at the 
se of the bluffs, twelve miles northeastward from Neb: 
os It is numbered from the top downward and designated 
as the — 
Fremont County Section. 
No.1. Thin bedded yellowish limestone, - - - 44 ft 
No. 2. Marly and carbonaceous shales, ee 
No.3. Impurecoly - .- - = = = 7 eg 
No. 4. Light bluish fire clay with fossil grasses? - - 2 “ 
