1890.] NEW YOEK ACADEMY OF bCIEXCES. 81 



was probably at the close of the Lower Silurian, and it was very 

 considerable. This topographic change must, however, have 

 been accentuated by the Triassic uplift. The stratigraphy of 

 the region of New York and "Westchester counties shows con- 

 clusively a general anticlinal structure with a southwesterly 

 pitch. 



If the Qaaternary uplift in the region between the Hudson 

 and Delaware Kivers had been in northern latitude alone, the 

 strike of the Cretaceous must have been made to diverge from a 

 direction parallel to the Trenton-Manhattan axis, and would 

 have been more easterly than it is at present. If, however, the 

 uplift had occurred parallel to that axis, any pre-existing par- 

 allelism between the strike of the Cretaceous and that of the 

 Trias would have been retained, and the relation would be such 

 as we find it. 



As no satisfactory evidence has yet been found that an uplift 

 occurred along the Trenton-Manhattan axis in post-glacial time, 

 the phenomena of the elevation of the coastal plain in a direction 

 normal to that axis may be explained by supposing that it was 

 elevated by movement along the greater Appalachian axes to the 

 northwest, which are essentially parallel in direction to the 

 Trenton-Manhattan axis. 



In connection with the matters under discussion, it may be 

 remarked that, in the estimation of the writer, the line described 

 by Mr. W. J. McGee' as a line of displacement, and which 

 follows the margin of the metamorphic terrane from Trenton 

 to the mouth of the Hudson, continuing northward along the 

 valley of the latter, is not the limit between a region which has 

 been elevated and one which has been depressed. It is not the 

 limit between drowned rivers and those which are still or 

 torrential. There are nearly as many drowned rivers on one side 

 of the theoretic fault-line as on the other. 



To the westward of this line, in the region assumed as one of 

 no downward displacement, the Raritan is a tidal estuary to New 

 Brunswick. In the Passaic, Hackensack, and their numerous 

 tributaries, tide-water flows for a distance of several miles, and 

 this estuarine region is occupied by a wide expanse of salt mead- 

 ows. In the Hackensack meadows, moreover, the stumps of 

 cedar trees are seen depressed below the level at which they could 

 have grown. Tiie old forest soil is overgrown with salt-marsh 

 grasses and overflowed by the spring tides. 



The channels of Murderer's Creek atNewburg, of the Wallkill 

 at Rondout, and of Esopus Creek, are drowned at their mouths, 

 and tide-water ebbs and flows in them. Again, on the east bank 



' Seventh Annual Report, U. S. Geol. Survey. 



