212 H. p. GUSHING UNCONFOR]MITY AT BASE OF BEREA GKIT 



and fill action on a delta floodplain. The more prominent channels on 

 the northwest seem more like definite stream channels, yet their depth, 

 their varying direction (they trend all the way from north-south to east- 

 west), and the evidence of rapid filling suggest that they may be scour 

 channels also. But definiteness here is not necessary to the point v/hich 

 we wish to make, namely, that on either view the erosion stage indicated 

 is a very juvenile one and points to a very short time gap between the two 

 formations. If the process was one of scour and fill in soft muds, cur- 

 rents adequate to the transportation of quantities of coarse sand and of 

 complete removal of all finer material from it as it was deposited were 

 competent to do the work in a very short time. If the westerly channels 

 were cut by individual streams and the rocks had their present degree of 

 induration, the time required would be longer, several times longer; but 

 even then the character of the channels is indicative of a very immature 

 erosion stage. They are cut in weak rocks, mostly very weak. They are 

 not broad; in fact, when the nature of the banks is considered, they may 

 all be said to be very narrow. Their tops are all at the same geologic 

 horizon and their bottoms at quite different horizons, even in the same 

 restricted district. There is not even an approximation to gradation in 

 the channel beds when compared with one another. Between channels 

 there was no removal of material at all. The whole physiography be- 

 speaks immaturity of erosion stage. And it was, no doubt, this phase of 

 the subject which impressed ISTewberry so forcibly that he made no point 

 whatever of the break when he built up his Ohio section. In these weak 

 materials wide-spread baseleveling would have resulted from a long ero- 

 sion interval, and the stream beds at least would have been thoroughly 

 graded in a shorter interval; but there is no approximation, even to the 

 latter. 



Precisely the same phenomena on a smaller scale are shown at the base 

 of the Euclid sandstone lentil in the basal Bedford shale. The sandstone 

 is argillaceous and of finer grain than the Berea; and though a shore 

 deposit, it is a marine one, even though the appearance of the sand badly 

 discouraged the marine fauna of the Bedford; yet the soft, underlying 

 shale is channeled in moderate fashion, and at the westerly margin of 

 the lens, in west Cleveland, sand-filled channels several feet in deptli 

 occur, with great disturbance of the underlying black muds. No one 

 calls this anything but contemporaneous erosion. 



The Berea rests always on the Bedford. To us the most obvious and 

 most conclusive evidence in support of our view of the trifling character 

 of the Bedford-Berea break is the fact that all across Ohio, along a meas- 

 ured length of oiitcrop of about 300 miles, from the Ohio Eiver north to 



