GEOLOGY OF THE NORTHERN ADIRONDACK REGION 439 



deflection of the Oswegatchie, Grasse, Raquette and St Regis from 

 their normal northwest courses to a northeast direction, so that 

 they flow parallel to the St Lawrence for many miles before 

 emptying into it, is an interesting feature which has not yet been 

 explained, though probably not difficult of explanation when the 

 ground is thoroughly studied. The Oswegatchie emerges on the 

 Precambric rocks of the Frontenac axis, and its behavior is 

 obviously controlled by the topography, as it takes a subsequent 

 course parallel to the ridges. But the other three streams make 

 their bend on the northern Paleozoic plain, and the cause can 

 hardly be a structural one. It must be sought in the Pleistocene 

 features of the region, either this portion of the plain having a 

 general slope to the northeast, owing to unevenness of glacial 

 deposits, or else morainic or beach ridges being the deflecting 

 cause. 



The streams of the eastern Adirondaeks mostly rise in the 

 neighborhood of the high peaks. The Hudson and Ausable have 

 their head waters in the high passes of that district. The Schroon 

 and Sacandaga head in the ridges east of the main axis. The 

 Saranac, on the north, heads in the Lake belt and is the only one 

 of the principal streams to cross the main axis of elevation, both 

 of its branches so doing. That portion of it which lies west of 

 the axis is separated from the present Raquette and St Regis sys- 

 tems by the most trivial of glacial divides, and undoubtedly 

 drained to the westward formerly. The date of capture by the 

 Saranac is not known. The easterly flowing Adirondack streams 

 have an advantage over those flowing west, owing to their steeper 

 slope, and tend therefore to extend their head waters westward, 

 causing the divide to migrate in that direction, away from the 

 main axis. That the capture occurred in preglacial times seems 

 very probable. 



Farther south, in eastern Hamilton county, the main axis is 

 crossed by two broad valleys, one running east from Long lake 

 and the other from Raquette lake. These are however located on 

 weak Grenville belts, on which it was easy for streams, flowing 

 eastward from the main axis, to push their divides westward 



