Pleistocene to P re-pleistocene of Mississippi Basin. 367 



streams must have been active, and. the deposition of the loess, 

 when the streams must have been sluggish. In point of fact 

 such conformity, or so much of conformity as this hypothesis 

 would demand, does not exist. The following diagrammatic 

 section shows the relationship which may be seen to exist 

 between the loess and the gravels and sands, at numerous 

 points in southern Illinois. 



Loess (I) covers the whole hill. Beneath it, the hill is 

 capped with gravel (a). This constitutes a well developed 

 layer, several feet in thickness. The pebbles composing this 

 layer almost uniformly lie upon their surfaces of greatest 

 diameter, and appear to be closely packed. The gravel may 

 be cemented or not. On the slopes of the hill below the 

 gravel layer, there are pebbles (a") few or many, identical in 

 character with those above. Unlike the gravel layer above 

 however, these pebbles have no particular arrangement, and 

 have the appearance of having rolled down the slope to their 

 present position. Along with the loose pebbles there may be 

 masses of conglomerate originating from the gravel above, in 

 case the same is cemented. Beneath the gravel, there is a con- 

 siderable body of sand (&), sometimes distinctly stratified and 

 sometimes not. Seams or pockets of gravel (a') identical in 

 character with that above, may occur in the sand, and occa- 

 sional pebbles exist where no well defined seam can be traced. 

 Laminae of the sand at frequent intervals are indurated (b\ 

 and bits of ferruginous sandstone derived therefrom, (V) are 

 freely mingled with the pebbles which have come down from 

 higher levels. The pebbles and the sandstone fragments lie 

 upon the eroded edges of the nearly horizontal layers of the 

 sand and gravel stratum. Together with these talus materials 

 there are often large numbers of iron- cemented sand- concre- 

 tions (<?'), identical in kind with those (c) which may be taken 

 from the undisturbed beds of sand. Like the fragments of 

 the sandstone, they originated close at hand, in the sand layers 

 of the hill itself. 



The erosion slopes of the hills, cut out of the horizontally 

 though irregularly stratified sands and gravels, are thus seen 

 to be strewn with gravel, sandstone debris, and ferruginous 

 concretions, originating from the same series higher on the 

 slope. Overspreading the whole, covering the crests of the 



