REPORT OF THE STATE PALEONTOLOGIST 1902 997 



erosion, does not correspond with exactitude to the succession of 

 events recorded by the dissemination of faunas and their internal 

 changes of composition. 



Perhaps no more effective illustration of the discrepancy in 

 these standards of classification could be brought forward than 

 that of the Portage sandstone, an element in this series of arenai- 

 ceous deposits — a well marked stratum which at the east of 

 this region contains a highly developed* Chemung fauna, but 

 westward carries no Chemung species whatever and still farther 

 west changes its lithologic texture also. Some hundreds of feet 

 of sediment under it in the east likewise carry a brachiopod 

 fauna, while in the west that fauna is wholly replaced in equiva- 

 lent and continuous strata. We could not therefore portray on 

 a map the succession of faunas for the Portage or lower belt of 

 these arenaceous strata, so that there would be any correspond- 

 ence to a cartographic portrayal of the succession of sediments. 



So far as we now understand the Olean and Salamanca regions 

 after the careful survey on which Professor Glenn has reported 

 and from a long standing previous acquaintance with the rocks 

 and their contents, it may be said that there is less probability 

 of discrepancy in the deductions derivable from independent con- 

 sideration of the stratigraphic and the paleontologic evidence be- 

 cause the uniformity of sedimentation is unaccompanied by so 

 pronounced differences in faunation. 



The most serious question involved in this survey so far as 

 concerns the classification of the rock formations, is the con- 

 struction of the Cattaraugus beds, the mass of chiefly red shales 

 and sands with their included conglomerate lenses. To indicate 

 the transitional character of these beds by employing as a pro- 

 visional designation Devono-Carbonic, as was at one time sug- 

 gested, is on the whole a makeshift satisfactory to no one. Hence 

 Professor Glenn has preferred to admit them, for the time being, 

 into the Devonic and to place the line of division between that 

 and the Carbonic system at the top of these red Cattaraugus 

 beds. 



It seems important however to take note of the two considera- 

 tions through which this provisional determination is reached: 



(1) a possible unconformity at the top of the Cattaraugus beds, 



(2) the assumption of continuity of these red beds with the 



