﻿GEOLOGY OF THOUSAND ISLANDS REGION 121 



Ruedemann has mapped two small faults on the Clayton and 

 Cape Vincent sheets and furnishes the following description : 



In Chaumont village (Clayton sheet) is a small outlier of Tren- 

 ton limestone, immediately to the west of which, and at the same 

 level, is Watertown limestone. The relations are best seen 

 about the viaduct on the Depauville road and along the railway 

 immediately to the east. Under the viaduct is Watertown 

 limestone. Along the railroad is Trenton at the same level, 

 with a cut which shows steeply dipping Trenton, the dip being 

 away from the Watertown and apparently due to drag on the 

 downthrow side of a fault. The fault downthrows to the east, 

 with a throw just sufficient to preserve the small patch of Tren- 

 ton on the downthrow side. Its trend is substantially parallel to 

 the road, or about northeast. 



On Carleton island (Cape Vincent sheet) the presence of a 

 fault cutting off the small western promontory, which consists of 

 Watertown limestone; is suggested by the depression which 

 separates the promontory from the mainland, within which no 

 rock shows, and which is faced by a rock cliff on each side, a high 

 Trenton cliff on the main island side and a lower cliff of Water- 

 town on the other. A small fault along the depression, with down- 

 throw to the east, is thus indicated. 



TOPOGRAPHY i 



The present day topography is the result of erosional forces act- 

 ing for long ages upon a land surface, which from time to time 

 varied in altitude and which underwent climatic changes. The char- 

 acter of the erosion, and of the resultant topography are also con- 

 ditioned upon the character, attitude and structure of the rocks 

 comprising the region. We have some slight knowledge of the 

 changes in altitude of the region. The climate has certainly varied 

 much, both in respect to temperature and to humidity, with, in quite 

 recent times, the climatic rigor of the glacial period. The erosional 

 forces, as always, have been in part atmospheric, but chiefly those 

 of moving water and ice. 



During paleozoic times the region was, when not submerged, one 

 of low altitude. It was uplifted somewhat at the close of the Paleo- 

 zoic, and during Mesozoic time seems to have been worn down to a 

 comparatively even surface of low altitude, in common with much 

 of the eastern portion of the continent. During the succeeding Ter- 

 tiary it participated in the general uplift of the same region, and its 

 present relief is chiefly a product of Tertiary wear. 



1 By H. P. Cushing. 



