GEOLOGY AND PALEONTOLOGY OF THE SCHOHARIE YALLEY 335 



It lias already been noted that the strata of this region dip 

 southward at about 135 feet to the mile, or approximately one 

 foot in 40. Thus it appears that the eYen upland surface, which 

 in fact gently rises southward, beYels across the strata, the 

 surface and dip being discordant, and the plateau therefore not 

 due to the strata composing it. In other words the surface of 

 the upland is an erosion surface which passes obliquely across 

 the strata, instead of being determined by a hard stratum at 

 that level, which might have largely prevented the degradation 

 below that general horizon. If thus the level is an erosion level 

 why did it stop so generally at a uniform hight, so as to give 

 the appearance of a level plateau, when this checking of erosion 

 was not determined by a uniform hard stratum which every- 

 where protected the summits at that level? The only adequate 

 answer to that question is: that when erosion had reached the 

 level in question, it could go no farther because at that time the 

 base level of erosion practically had been reached. In other words 

 the sea level at the period during which the ancient surface 

 was worn down to the plateau level, was about 2000 feet higher 

 in this region than now, or the land stood so much lower with 

 reference to the sea. All the valleys which cut below that level 

 were made subsequently to it, when a relative change in the 

 land and sea levels took place, the former rising or the latter 

 falling. The more or less even surface near sea level, which 

 characterized the end of this earlier cycle of denudation, was 

 due wholly to the working of subaerial agencies and not to 

 marine erosion, there being absolutely no evidence of the occu- 

 pancy of this region by the sea, in Postpaleozoic time. Thus 

 this approximate plane of erosion falls under the type to which 

 the name "peneplain" is applied by physiographers, while the 

 high peaks of the Catskills which dominate this peneplain fall 

 under the type known as " monadnocks." As just stated, the 

 Schoharie and other valleys cut into this upland are of later 

 origin and therefore belong to the present cycle of erosion, of 

 which they represent the initial effects. 



