338 77/e A iiicricii II (iaoUKjist. DccoiuIkt, lyys 
RIVER VALLEYS OF THE OZARK PLATEAU. 
IJy Oscar II. Heksiikv, Frocport, III. 
In traveling over the Ozark plateau or so-called Ozark 
mountains in Missouri and Arkansas, the writer was sur- 
prised at the comparative narrowness of thi^ immediate valleys 
of the streams, and was led to make an investigation of the 
subject, of wliich the following observations and conclusions 
are the result. The study is far from complete, but it is 
hoped that this paper may contain some suggestions for 
future researches into the geomorphology of the Mississippi 
basin. 
The Ozark region has been frequently des<'ribed, and 
the majority of readers are doubtless acquainted with its 
topography. It is essentially a plain which has been elevated 
into a broad, dome-shaped " u])lift,"' and subsequently it has ' 
been sculptured by erosion into very numerous deep antl gen- 
erally quite narr(»w valleys, with narrow, steep-sided ridges 
between. The crest or water-shed of the plateau has mostly 
an undulating or moderately rolling surface, while the exceed- 
ingly hilly and mountainous country occupies the border por- 
tions of the uplift. The rock strata consist largely of mag- 
nesian limestones and intercalated sandstones of Upper 
Cambrian and Lower Silurian age, with cherty limestones and 
shales of Lower Carboniferous age resting on them toward 
the north, west, and southwest. The conglomerate sandstone 
of the base of the Coal Measures is also present, over the 
Burlington limestone, well wdthin the limits of the uplift, as 
isolated remnants of a once more extensive formation. The 
dip of the strata is gentle and regular, so much so that they 
are perhaps more nearly horizontal than are the same form- 
ations in any other portion of the American continent. 
The Juka-( 'Retaceous Peneplain. 
It does not take the traveler in the Ozarks very long to dis- 
cover that lunirly all the ridges rise tf) about the same hight, 
and that, were the intervening valleys tilled up to the level of 
tlie hill tops, we should have a nearly level ])lain. On the 
hard Burlington limestone areas, one will frequently h)ok for 
many miles across the countiy and see only, in appear- 
ance, a vast timbered plain, although it is one of the roughest 
regions east of the Rocky mountains. 1'his ancient and 
