446 NEW YORK STATE MUSEUM 



type> in that they seem to occupy portions of more than one valley, 

 the valleys being closely adjacent and the divides low, and their 

 greater breadth being thus accounted for. There are rock islands, 

 in fact, in all of these large lakes and often in considerable 

 number. Lower Saranac lake is full of them, alined so as to 

 suggest the drowning of adjacent small valleys. The chain of 

 islands in the center of Big Tupper lake suggests the same thing. 



The smaller lakes are of a great variety of types. Some of 

 them are in narrow and some in wide valleys; some are nearly 

 or wholly rock bound, while others show little or no rock along 

 their shores; some are in deep, steep sided valleys, while others 

 have low, sloping shores; some are strung out in chains along a 

 single valley, though the majority are single. 



The causeis for the existence of these lakes are as various as 

 the causes which produce hollows on the surface of a regioo 

 recently invaded by an ice sheet, such a surface having a com- 

 biination topography due to both destructive and constructive- 

 processes. It is held by many observers that locally glaciers 

 may excavate shallow rock basins, and Ogilvie has argued that 

 lake basins of that type are abundant in Hamilton county.^ 

 Quite likely also such exist in the north portion of the region, 

 though they certainly are mot the common type there, the 

 majority occupying' depressions in the drift surface in the wider 

 valleys. Such a lake as that shown in plate 16, for example, 

 is a good representative of the usual type. This lake, Stony 

 Creek pond, shows occasional rock ledges on its east shores, but 

 it lies on the east edge of a great sand terrace which extends 

 from the south end of Upper Saranac lake to Axton on the 

 Raquette, the sand undoubtedly overlying till at no great depth, 

 so that we are dealing with a small preglaciial valley now badly 

 clogged with drift. The level of the pond is so nearly that of 

 the modern Raquette at Axton that its outlet has no cutting 

 power. 



The larger lakes are mostly up near the main divide of the- 

 region; and, though they occupy portions of preglaciial valleys,, 

 these were toward the head waters of the preglacial streams 

 and were therefore of no great width. Their south to southwest; 



^Op. cit., p.411. 



