﻿GEOLOGY OF THOUSAND ISLANDS REGION 133 



berry is surrounded by quartzite and granite and there is no known 

 evidence of limestone in the bed. 



Whether these basins were dug out by ice, or have resulted from 

 warping, we are unable to say. In either case we can not see why 

 no lake was formed in the valley which heads at Browns Corners, 

 and is of identical type with the others. The extreme head of 

 a valley up which the ice was moving would seem an unlikely place 

 for it to dig. Solution of limestone may have aided in the forma- 

 tion of some of the basins. Though we are unable to account for 

 them to our satisfaction, their localization seems to us unquestion- 

 ably due to the localization of the especial type of valley heads in 

 which they occur. 



Underground drainage 



It has previously been shown how, in the more soluble limestones 

 of the district, chiefly the Black River and upper Lowville, rain 

 water widens the joint cracks by solution, and much of the surface 

 water of the district passes down through these fissures to under- 

 ground flow [pi. 26 and 27]. The Leray limestone is more soluble 

 than the Lowville and the chief underground drainage of the 

 region is in Leray districts, the underground waters running 

 along on the upper surface of the Lowville, slowly enlarging 

 their channels by solution. But there are also underground waters 

 in the Lowville the upper beds of which are more soluble than those 

 beneath. Even in the Theresa formation similar action is at times 

 seen. In plate 35 may be seen bared Theresa surfaces in the bed 

 of a brook, with joints considerably enlarged by solution, sufficiently 

 so to allow the water of the creek to entirely disappear through 

 them, to emerge a few yards away at the base of the cliff shown in 

 plate 15, the cliff being part of the rock wall of a somewhat filled 

 Tertiary valley, that of the Chaumont river. During the spring 

 floods the underground channel can not care for the entire flow, and 

 part of it remains at the surface, flowing over the rock exposed in 

 the view. In the Leray and Watertown limestone districts are many 

 stream beds of bare rock, totally dry throughout the summer, with 

 their waters underground, but showing plainly the incapacity of the 

 underground channel to care for flood waters, which flow in part at 

 the surface, and keep the beds thoroughly washed out. Examples of 

 such are the creek coming into the Black river from the south at 

 Felts Mills (southeast corner of Theresa sheet), and the bed of 

 Philomel creek near Brownville. Much underground water comes 

 into the Black river, all across the district. 



