Bh'er Va//ei/s of tht Ozark Plateau. — Ilers/ici/. ."Ul 
at the head of Pine run in Stonc^ county, and overlooks inueh 
of the surrounding country. It is composed of strata yielding 
more readily to surface erosion than the sandstone ridge at 
Scholten, and hence is less prominent. Its topography resem- 
bles that of the plateau country, of which it may be consid- 
ered an outlier. 
Only in one way can the steep-sided sandstone mounds and 
ridges have been produced, namely, by erosion. There are 
several ways by which the shallow basins on the peneplain 
may have been produced. They may be due to warpings of 
the earth's surface since the post-Cretaceous elevation of the 
Ozarks. Warping has certainly occurred over most of the 
Ozark region, but, in that particular portion of it under 
consideration, the strata are so nearly horizontal that no 
great amount of warping can have occurred. Besides, the 
basins form such a regular system, and have such relation to 
the rocky strata under them, that some form of erosion, 
instead of warping, will better explain all the phenomena. 
These shallow basins may be supposed to have been pro- 
duced by subaerial erosion since the elevation of the pene- 
plain. The broader ridges are flat-topped and quite regular 
in hight. They gentl}'' descend from the sides to the center 
of the basin. Now, surface erosion should be iuWy or nearly 
as much at the edges of the basins as in the center. Where 
the edges are narrow, the effect on the streams on either side 
has been to depress them from 10 to 25 feet. Hut this is 
quite unlike the steady slope of a ridge from one end to 
another. Again, the centers of the larger basins are some- 
times 50 to 100 or more feet lower than the rim. Ordinar}^ 
surface erosion in a hillj'' country could not be the cause of 
this. In short, it may be said that the theory of surface 
erosion since the elevation of the peneplain is inconsistent 
with the i^henomena of the basins. 
One other hypothesis remains open for inspection, nainelj'^, 
that the almost imperceptible basins here discussed are the 
outlines of the hydrographic l)asins of tlie streams wliich 
flowed on the Cretaceous lowland pl;iin. Tliis hy|)othesis 
seems to explain all the plnMioiiiciia. 'I'hc haseleveling of 
the region was nearly cimiplctc. 'I'hc rims of our l)asins 
occupy the situations of the dividing cols of the nnciciit 
