LOWER OHIO DRAINAGE SYSTEM. Ill 



feet, above tide, but a few miles back they rise to about 1,000 feet. There 

 is a simihir breaking down on the liorders of the Ohio in each of tlie for- 

 mations to the west. In \'iew of this condition of the formations on the 

 border of the Lower Ohio, there seem to be grounds for considering it a 

 ver)- old drainage line, whose course was adopted before the present pro- 

 nounced escarpments and basins had been formed. 



TERTIARY FLUVIAL DEPOSITS. 



The great age of the valleys of the Lower Ohio and its tiibutaries is 

 also shown by the occurrence, on high terraces bordering the canj^on val- 

 leys, of deposits of sand and gravel which appear to be fluvial and bear 

 evidence of transportation to some extent in the present direction of di'ainage. 

 These deposits were long ago recognized by Cox on the borders of the Ohio 

 in southern Indiana,^ and by SafPord on the borders of the Tennessee and 

 other streams of Tennessee and Kentucky." More recentl}^ they have been 

 noted and described on the Cumberland, Kentucky, and Licking rivers by 

 Miller,^ and on the Kentucky River by Campbell.* 



The deposits noted by Cox cap the bluffs of the Ohio near Cannelton, 

 Ind., at an altitude of about 350 feet above the stream, or nearly 700 feet 

 above tide. The present writer has traced them eastward or up the Ohio 

 Valley from the points noted by Cox, and found that they are preserved in 

 small detached remnants on the bold bluffs of the Conglomerate Coal 

 Measures and Kaskaskia formation, on both the Indiana and the Kentuck)^ 

 side of the narrow river valley, as far as the eastern border of the latter 

 formation. As now preserved, they are only 10 to 20 feet in depth, and 

 the original thickness may have been but little more. Their altitude is 

 above the general level of the basin which has been formed in the St. Louis 

 limestone to the east, but in their rock constituents these deposits bear 

 clear evidence of derivation from the cherty portion of that formation. 

 The transportation must have been effected before the basin had been 

 formed in the St. Louis limestone, a fact which testifies strongly to the 

 great age of the deposits. 



1 Tertiary deposits, by E. T. Cox: Eept. Geol. Survey of Indiana for 1871 and 1872, p. 138. 



-The eastern gravel, by J. M. Safford: Geol. Tennessee, 1869, p. 438; see also pp. 434-437. 



' High-level gravel and loam deposits of Kentucky rivers, by A. M. Miller: Am. Geologist, Vol. 

 XVI, 1895, pp. 281-287. 



•• The Irvine formation, by M. R. Campbell: Geologic Atlas of the United States, folio 46, Rich- 

 mond, Ky., 1898. 



