May, 1908.J Stream Diversion near Lakeville, Ohio. 353 



valle3^s 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 h^'pothesis 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 w^as found. 

 No volcanic lava or ejecta occur here. In fact, the glacial drift 

 is the only 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. B}^ 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, w^hich 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- 



