May, 1908.J Stream Diversion near Lakeville, Ohio. 
353 
valleys enter the main valley essentially at the top of the gorge 
of the main valley showing that when the rejuvenation occurred, 
the valley bottoms of laterals and the main valley floors were 
at accordant levels, just as are those of the present streams. 
South of the narrows on Muddy Fork similar conditions obtain, 
and likewise adjacent to the narrows of Black Fork the phe¬ 
nomena of hanging valleys and recent gorges in their floors are 
repeated. 
This whole series of facts makes it very certain that the 
streams have been diverted from their old courses and forced 
over low divides and made to flow in new courses. We are 
ready then to formulate an hypothesis to explain the observed 
facts. The hypothesis must account for all the facts and be in 
harmony with the general conditions of this part of the state. 
It was pointed out that there were large deposits of glacial 
drift in several of the valleys in this vicinity. Glacial moraines 
are especially developed in the large east and west valley from 
north of Loudonville to north of Shreve, also in the broad valley 
north of Big Prairie. Neither of these valleys contains a large 
stream except for short distances while the smaller valleys with 
relatively less drift contain the larger streams. The slopes of the 
valley walls are not steep enough for landslides to occur and 
interfere with drainage and no evidence of landslides was found. 
No volcanic lava or ejecta occur here. In fact, the glacial drift 
is the onlv material found about here which could plug up valleys 
and divert the streams. But diversion might be caused by 
tilting and folding of the strata if these had occurred. Folding 
and faulting sufficient to induce the stream modifications noted 
are unknown here. Superposition caused by a leveling up 
sufficient to send streams over hills and cause them to select en¬ 
tirely new courses independent of old courses has not occurred. 
Moreover the strata are similar sedimentary rocks all through 
the region so that neither superposition nor change in the char¬ 
acter of the rocks encountered as the streams cut down can be 
used to explain the conditions. Rejuvenation has been con¬ 
sidered. There has been no local uplifting that could rejuvenate 
in some places and not in others as the conditions would re¬ 
quire, nor are the results those consequent on broad or general 
rejuvenation. Streams in isolated areas only are revived and 
entrenched. By elimination, we are left to the drift as the im¬ 
mediate cause of the obstructions and diversions. A study of 
the drift shows it to be deposited in loops and curves as if around 
the ends of ice tongues extending southward along the valleys 
and against the margins of broader ice lobes, which must then 
have advanced into the region from the north. 
Working out the relations between the theory of ice invasion 
of these valleys, and the facts observed regarding stream diver- 
