290 NEW YORK STATE MUSEUM 



total amount of wear since Utica time has been exceedingly small, 

 and the surface must have been for much of the time near base 

 level. Moreover, such blocks were the most downfaulted of all 

 and must have formed depressed basins with every period of 

 renewed faulting, as such receiving deposit from the surrounding 

 higher blocks as these were worn down, thus protecting their own 

 surfaces from wear for long intervals. 



This erosion interval was so protracted, extending through the 

 greater part of Mesozoic time, that the whole region was finally 

 planed down to a surface of little relief, broad shallow valleys and 

 low divides, with occasional low, rounded hills or clump of hills 

 where extraresistant rocks occurred, or where favorable location 

 prevented maximum wear. The fault cliffs, or scarps, were en- 

 tirely wiped out as topographic features, the raised side being 

 worn down to the same level as the dropped. 



In the southern and western Adirondack region this old sur- 

 face is still recognizable, as the upland surface into which the 

 present valleys are cut, the old residual hills rising above it now 

 as they then did. The present plateau upland of sioutheastern 

 New York would seem to represent a continuation southward 

 of this same old surface; and, if this be the case, the result in the 

 Adirondack® was sinyDly a local development of conditions which 

 prevailed widely in the eastern United States at this time. 



Cenozoic history 



This long period of quiet wear was terminated by another uplift, 

 which would seem to have occurred at the close of Mesozoic, or the 

 beginning of Cenozoic time. This uplift inaugurated another ero- 

 sion cycle with a much lower base level. In the Adirondack 

 region this uplift was, at least for the northern part of the dis- 

 trict, of a dome-shaped character, the major axis of the dome 

 being along a nearly north-south line closely coinciding with the 

 line between Clinton and Franklin counties, thence turning south- 

 westward; the minor axis running through the extreme south of 

 Franklin county and thence eastward through Essex. In the 

 eastern Adirondacks this uplift was complicated by further shift- 

 ing along the fault planes, bringing fault cliffs, or scarps, again 



