306 F\ REPORT OF PROGRESS. B. W. CLAYPOLE. 



logical interpretation of the absence of a stratum, if that 

 Stratum occurs in close neighborhood to the place. 

 Wherever the sea exists there sediment is deposited, and 

 there is no reason to doubt that the same was true in the 

 past. Consequently the inference is logical that wherever 

 sediment was not deposited there was dry land. We thus 

 come to the conclusion that Rye township was above or 

 nearly above sea-level duringpart of the interval that elapsed 

 between the close of the deposition of the Onondaga shale 

 and the commencement of the deposition of the Hamilton 

 sandstone which lies upon it. This is the earliest glimpse 

 of land revealed in the county.* 



Here is evidence of one of those changes of margin and 

 level to which allusion was made in the chapter on the 

 early geological history of Perry county, one of those fluc- 

 tuations to which the palaeozoic ocean of North America 

 was subject in consequence of variation in the rate of de- 

 pression and deposition. By this variation Rye township 

 was temporarily raised above the water-level, and other 

 changes, now to be mentioned, were induced. 



After what has been already said on the subject of ero- 

 sion no proof will be needed of the assertion that if Rye 

 township was above water at the time in question some part 

 of the surface must have been washed off. The amount we 

 have at present no means of determining. Now an exami- 

 nation of the ground has shown that over such part of the 

 township as allows an opportunity for inspection the Onon- 

 daga gray shale and some part of the Onondaga variegated 

 shale are absent. This is the case in the section at Marys- 

 ville, as will be detailed below. Only a part, and that the 

 lowest part, of the Onondaga variegated shale is there 

 present. 



The question then arises, u Were the Upper Onondaga 

 variegated shales and the gray shale ever deposited here or 

 have they been since removed V ' The question is very diffi- 

 cult to answer. But judging from the facts that have been 



♦This was written before I had proved the absence of the Corniferous lime- 

 stone over the whole county, whereby an earlier land surface was demon- 

 strated. 



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