44 NEW YORK STATE MUSEUM 



The order of events now indicated is (a) peneplain.ation, then 

 (b) sHght upHft and further deep weathering or rotting under 

 moist and warm chmate, next possibly (c) glaciation, followed by 

 (d) arid, cold, desert conditions with free sweep to the winds, 

 finally (e) slow submergence under an encroaching sea. 



That this sea came in from the northeast is well known. ^ It 

 appears to have first invaded our quadrangle from the east as a 

 bay making westward from Hannawa and finally penetrating nar- 

 rowly through the Harrison Creek strait as far as Dekalb (Gou- 

 verneur sheet). Whether it was simultaneously entering the north- 

 ern border of the quadrangle as the edge of a large and deeper 

 bay occupying the primitive St Lawrence valley can not be certainly 

 told until well-drilling proves the existence of the red beds there, 

 but such is the general assumption and our cross-sections are 

 based upon it. 



The sea continued to advance and red sandstones to be deposited 

 until probably the most of the southern third of the quadrangle 

 was submerged and a hundred feet or more of strata had been laid 

 down in the deeper hollows. At this juncture a slight uplift with 

 some disturbance, crushing and faulting, of the unconsolidated 

 sands seems to have taken place; and the time interval appears to 

 have been sufficient for induration of the sands into firm sandstone. 

 In places, heated waters seemingly percolated up through the beds, 

 jasperizing the sand matrix of the basal breccias and possibly some 

 of the adjacent Grenville quartzites at the same time. Mineraliza- 

 tion of the residual iron ores at Dillabaugh's and elsewhere may 

 also be the work of this time. The extent of this disturbance and 

 the length of time it consumed can not now be affirmed. There 

 are some reasons for thinking it was a break of major importance, 

 so that the true red Potsdam sandstones would be much older than 

 the upper white division which carries the Saratogan fossils — 

 possibly even Lower Cambrian (Georgian) or Keweenawan. But 

 other facts seem to point to a lesser import. 



However great or however slight the interruption, the returning 

 sea found a change in climate, with vegetation decolorizing the 

 sands now supplied to it. Its waters reoccupied the Hannawa- 

 Canton bay spreading a thin basement of pebbly sands, and crept 

 upon us also from the north and west (Rensselaer Falls), gradually 



^ It is highly desirable that the reader should become familiar with 

 Professor Cushing's conclusions in Bulletins 95 (pages 272 to 294) and 

 145 (pages 8 to 60) of the N. Y. State Museum, without which these 

 pages would not likely have been written. 



