﻿142 NEW YORK STATE MUSEUM 



great valley shows all the strata from the Pamelia to the Oswego 

 sandstone. The east wall of Precambric rocks is deeply buried un- 

 der sand plains or delta deposits accumulated in glacial waters. 1 The 

 axis of the deepening and north leading valley migrated westward, 

 down the slope of the basal crystallines and against the outcrop of 

 the sediments. 



The great ridge dividing the Black and Ontario valleys now 

 terminates abruptly in the Rutland promontory with a limestone 

 scarp about 400 feet high. The point of this promontory is shown 

 on the lower edge of plate 44, south of Felts Mills and Black River 

 villages. A glance at the Watertown sheet will show how the river 

 below Felts Mills clings to the foot of the scarp. A moment's 

 thought will make it evident that these thick limestones did not 

 originally end here, but must have extended far north, overlying the 

 district toward the St Lawrence. It seems perfectly evident that 

 the stratigraphic relations and the erosional conditions which pro- 

 duced the Black valley above Carthage must once have extended 

 much farther northward, and the Tertiary river probably had its 

 course northward along what is now the east slope of the St Law- 

 rence valley, in continuation of the Forestport-Carthage valley. The 

 problem is therefore narrowed to the question of the time of the 

 removal of the Trenton limestones north of the Rutland promon- 

 tory, and the date of the diversion of the river from its northward 

 into its westward course. 



A singular physiographic feature of the region is the northward 

 or rather northeastward direction of all the heavy streams north 

 of the Black river. These all flow along parallel with the St 

 Lawrence, and in some sections at even lower levels. In normal 

 stream development the tributaries should flow toward the trunk 

 stream. The Indian, Oswegatchie, Grass, Raquette and St Regis 

 are more or less independent of the St Lawrence and are not normal 

 tributaries. Their courses have probably been modified, straight- 

 ened and their parallelism emphasized by repeated glaciation, but 

 the latest ice erosion has certainly been insufficient to produce such 

 channels. Their direction is in precise opposition to the glacial 

 effect and also in opposition to the postglacial uplift of the region. 

 It is in harmony with and in continuation of the Black valley, 

 curving eastward around the uplifted mass of the Adirondacks. It 

 seems altogether likely that these stream courses were developed 

 by north leading drainage having practically the same stratigraphic 



1 See a paper by the writer, Glacial Waters of the Black and Mohawk 

 Valleys. N. Y. State Mus. Bui. In press. 



