﻿I36 NEW YORK STATE MUSEUM 



River village, Watertown, Brownville and Dexter; and at each 

 locality use is made of the water power. Every one of the falls 

 is over the massive Leray limestone into the Lowville beneath, as 

 well shown in Ulrich's excellent panoramic view of the main 

 fall at Watertown [pi. 42]. There are minor falls of the same 

 type -between the chief localities. Below the fall the river flows 

 along in the Lowville until the steepened dip on the western limb 

 cf an anticlinal fold carries the overlying Leray limestone down 

 to, and beneath, the water surface, forming the bottom of a shallow, 

 synclinal trough [see pi. 28 for such steepened dip at Brown- 

 ville]. In this the dip flattens, and then becomes low east, bring- 

 ing the Leray base back to stream level, and giving opportunity 

 for development of the fall as the water passes on to 

 the less resistant Lowville beneath, the fall so begun slowly 

 cutting back up stream with gradual increase in hight. Down 

 stream the river remains on the Lowville under the general low 

 anticlinal arch, until the drop of its western limb again puts the 

 Leray limestone beneath the river level, with repetition of 

 the previous conditions and another fall where the limestone comes 

 back again. Because of the westerly dip the western limb of the 

 anticlines is steeper than the eastern, and the river cuts the bottom 

 of each syncline at substantially the same horizon. The diagram 

 [fig. 12] will illustrate the conditions, which are somewhat excep- 

 tional, better than can be done verbally. 



Fig. 1 2 Diagram illustrating the rock structure which gives rise to the successive falls 

 in the Black river, the heavy line representing the river bed with three falls, and the sinu- 

 ous dotted line the base of the Leray limestone, showing how, due to the folding 

 each fall is over the same rock horizon as its predecessor. Dips and fall of river muc^ 

 exaggerated 



PLEISTOCENE GEOLOGY 1 

 History 



A brief outline of the Pleistocene history and its relation to the 

 earlier time is given on pages 23 and 24. 



At least three distinct episodes are recognized in the recent geo- 

 logic history of our region. These are (1) burial under the ice 

 sheet, (2) burial under standing waters, (3) renewal of the ex- 

 posure to the atmosphere. 



Glaciation. The glacial theory has long since passed into the 

 category of accepted fact. That our area has been subjected to 



iBy H. L. Fairchild. 



