352 OHIO STATE ACADEMY OF SCIENCE 
volume of water greatly exceeded that now discharged through 
the valley.” 
We have seen why the volume of water should be greater than 
at present; but as vet have given no reason why the flow should 
not be correspondingly vigorous. That it was greater, is evident 
from the loess at Cape Girardeau; and as this is near the wide 
flood plain on which the water could rush out as into a sea, the 
obstruction that would hold it back must be close at hand. 
Leverett says, again, “The Ohio at one time discharged either 
wholly or in part through the ‘Cache Valley, which crosses southern 
Tlinois a few miles north of the present course of the Ohio.” 
The ‘clay deposit stands only about seventy-five feet above the 
present stream. [It] has sufficient depth to extend to river level, 
and it may extend much lower.” — The “Grand Chain of the Ohio,” 
crosses the river below the point of divergence of the old channel 
from the one now occupied by the river. 
Clearly, we have here a condition similar to that at Thebes. 
At the time under consideration the Ohio received all the glacial 
discharge east of that flowing into the Illinois and Mississippi, in 
addition to the floods from its southern tributaries swollen by 
rainfall greater than we now know. ‘These torrents flowed through 
Cache valley, over a bottom which is now seventy-five feet above 
river level. The water thus discharged would equal or perhaps 
exceed that coming from the north; each great river would retard 
the flow of the other, and in the comparatively sluggish currents 
above their junction sediment would come to rest. This condition 
prevailed until the ancient beds, excavated in geological ages ante- 
dating the glacial period, were filled up. At Grand Tower and 
at Thebes, the Mississippi when it was once more free to flow south- 
ward without hindrance found the clefts through which it now 
flows, lower than the silt in its old channel. So the Ohio Cache 
valley was filled to a level higher than the crevices in “Grand 
Chain,” and the water made its way through these. Probably the 
Tennessee had discharged directly into the Mississippi; but this 
region has not been fully studied. 
The sharp peaks, bluffs, and ridges of loess on the upper rivers 
are the counterparts of the broad bottom lands along the lower 
Ohio. In the one case, the land is high enough above sea-level to 
permit aerial sculpturing; in the other, erosion can not act because 
the gradient is almost at the base line. All, alike, are due to sedi- 
ments earried by glacial floods; the components being the various 
earthy materials which ice and water have ground from rocks, 
picked up from soils, mingled by ceaseless grinding and washing, 
and finally carried in suspension until in quiet waters behind pro- 
jecting hills, or in lake-like expanses of over-flowing back-water, 
they settle to the bottom to form picturesque landscapes where 
carved by winds and frost, or stretch out in plains of wonderful 
fertility where these agencies do not erode them. 
