PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 7 



curving courses of the Grass and Raquette rivers to their mouths, 

 after leaving the crystalline rocks, agree so nearly with the curving 

 orientation of the drumlins as to need no better explanation, though 

 within the map limits the Raquette is for a space bandied back and 

 forth among the drumlins. The lowest point on the map is not 

 on either of these principal rivers but at the exit of Trout brook, 

 intermediate between them. Even in the southern part the drain- 

 age is not wholly adjusted to the rock belts, for its devious chan- 

 nels there are determined in part by glacial and postglacial deposits, 

 including the delta sand plains built by the streams themselves 

 awhile ago into the lowering series of glacial lake and marine water 

 levels whose history is summarized beyond. 



In the nature of its Paleozoic rock geology the Canton district 

 is intermediate or transitional in type from an extensive belt on 

 the east where the Paleozoics are said^ to abut continuously against 

 a rather abrupt Precambrian front from which they decline quite 

 steadily northward presenting linear zones of outcrop, to a mark- 

 edly different area at the southwest where^ the Paleozoic rocks, at 

 least the so-called Potsdam, are somewhat folded and now largely 

 cut up by erosion into scattered outliers among the crystallines.^ 



ST LAWREN 



Fig. 2 Diagrammatic north-south profile showing the relations of the three 

 peneplains in the vicinity of Canton ; drift omitted. The peneplains are 

 numbered in order of age. (Vertical scale greatly exaggerated) 



The transition is accompanied by a sharp offset in the formation 

 boundaries as they enter our quadrangle from the east (see the 

 key map, figure i), signifying the emergence at this point of a 

 rugged sub-Potsdam surface that seems to be deeply buried in 



^ l6th Rep't N. Y. State Geologist, p. 5-6, 15, and the map. Also N. Y. 

 State Mus. Bui. 95, P- 433—34- 



^ 19th Rep't N. Y. State Geologist, map opp. p. r8s. Also 13th Rep't 

 ibid., p. 496 and map opp. p. 492. 



3 i6th Rep't cit., p. 6. Also 59th Rep't N. Y. State Mus., p. 10, and 

 N. Y. State Mus. Bui. 145, p. 112-15; maps. Compare also the paper by 

 Brooks in Amer. Jour, of Sci., 4:24 (1872). 



