BYBEE-MALOTT : THE FLOOD OF 1913 



117 



sediment is found where the current is less — that is, near the bot- 

 tom, surface, and sides of the stream. 



Another class of debris that is carried by a stream in times 

 of flood includes tree trunks, logs, rails, bridge planks, boards, 

 telephone poles, and everything that will float or that can be held 

 up by the current. These things cause much damage in that they 

 have a tendency to form a dam whenever they may become lodged. 

 In this way many bridges are washed away. The road west of 

 Martinsville was damaged to a great extent by the cross currents 

 set up by the debris catching on the wire fence on the north side of 

 the road and forming a dam. L. C. Glenn, in ' Professional Paper 

 No. 72, U. S. G. S,' cites many illustrations of mills and power 

 plants having been destroyed by floating debris becoming lodged 

 against them and finally forcing them from their foundations. 



Since the drainage of both forks of White River is closely 

 associated with the geological structure, a brief discussion will be 

 given at this time. The geologic history of the State is embraced 

 by the Paleozoic times. The geological scale for Indiana is as fol- 

 lows: 



Geologic Stkucture of Indiana 



Pennsylvanian 



f Merom sandstone 



\ Coal measures 



[ Mansfield sandstone. 



Mississippian 



Chester sandstone and limestone 

 Mitchell limestone 

 Oolitic limestone (Salem) 



] Harrodsburg limestone 



I Knobstone sandstone and shales 



1^ Goniatite limestone. 



Paleozoic 



Devonian 



f New Albany black shale 

 I Sellersburg limestone 

 I Silver Creek limestone 

 [ Jeffersonville limestone 



Silurian 



Ordovician 



Richmond limestone and shales 

 Lorraine limestone and shales 

 Eden shales and limestones 

 Trenton limestone. 



