PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 47 



shows the actual dips there observed, without the exaggeration of 

 the other sections. Brecciation, or micro faulting, is among the 

 other evidences of the crushing to which these brittle sandstones 

 have been subjected, apparently through being squeezed between 

 the jaws of a Precambrian vise that consisted of an older synclinal 

 fold of gneiss with a marble core.^ 



Subsequent Geologic History 



The complete induration of the Potsdam sandstones seems to 

 imply that they were for a long time under the " load " of many 

 hundreds of feet of overlying strata. What these strata could 

 have been is not so easy to answer. Discounting the conjectural 

 Trenton outlier, they may have consisted in part of the Beekman- 

 town, Chazy, and perhaps Black River, Trenton, Utica and less 

 probably the Lorraine and Oueenston formations. To these, or 

 without them, it is even possible there were added now vanished 

 Silurian and Devonian deposits. In fact we can not be sure that 

 all marine deposition ceased in the upper St Lawrence valley until 

 the end of Middle Devonian time, and unknown continental fillings 

 may have continued to be heaped in from the wasting Adirondacks 

 only to be carried on out again. - 



By general consent the area has come to be looked upon as one 

 that has remained moderately near to sea level throughout the long 

 post-Precambrian times, but this may be erroneous. It may have 

 been much depressed, and also much elevated, though today (per- 

 haps accidentally) back at about the same stand. But at the close 

 of the ^lesozoic^ it, and the areas adjacent even far into the Adi- 

 rondacks, had reached the flatness of surface that comes from long 

 erosion at one level and which is called a peneplain. The surface 

 of this peneplain (figure 2) is that of the present high land from 

 Waterman hill southward, visible from Canton as a nearly smooth 

 sky line but far more impressive when seen from the standpipe hill 

 south of Gouverneur. Into this peneplain, after its elevation, the 

 rivers of Tertiary time cut deep and often not very wide valleys. 

 But at the same time they opened out a wide flat-bottomed valley 

 (figure 2) along the belt of Paleozoic rocks for the St Lawrence 



* Geol. Soc. of Amer. Bui. 26, p. 292-94, figs. 7-9. 



■^ A summary of the evidence bearing on the former thiclcness and 

 extent of the Paleozoic strata is contained in Museum Bulletin 18 of the 

 Canada Department of Mines, pages 19 to 22 (1915), h"- '^*, M. Kindle 

 and L. D. Burling. 



