GEOLOGY OF THE NORTH CREEK QUADRANGLE 45 



The important outlier at Wells (Lake Pleasant sheet), which 

 shows rocks from Potsdam to Canajoharie, has been known since 

 the early days of the State Survey. The nearby occurrences of 

 Little Falls dolomite along the southern portion of Lake George 

 should also be mentioned. 



Within the map limits, certain drift boulders are significant as 

 showing proximity to concealed outcrops or ledges which were 

 scraped ofit by ice erosion. Thus a fragment of Potsdam sandstone 

 2 feet across and very angular was seen just east of the old garnet 

 mine near Daggett pond, and many Potsdam fragments up to i foot 

 across occur in the river valley bottom between Moon and Heath 

 mountains. 



The occurrences of early Paleozoic marine strata on all sides of 

 the North Creek quadrangle furnish practically conclusive evidence 

 that much, if not all, of the area of the quadrangle was covered 

 by that early Paleozoic sea. Thus the Potsdam (upper Cambric) 

 sea, which encroached over northern New York from the north- 

 east, must have swept over the North Creek region and this was 

 quite certainly succeeded by the Theresa and Little Falls seas. 

 Regarding the presence or absence of the Ordovician sea, we have 

 no positive knowledge, though the Wells outlier suggests that it, 

 too, was present. 



It is well known that when the Potsdam sea encroached upon the 

 eastern Adirondacks, the region was greatly worn down to the con- 

 dition of nearly a peneplain. Since some portions stood out above 

 the general level of the peneplain, it is quite possible that the Pots- 

 dam sea, and even the later Cambric, did not cover the higher por- 

 tions as Professor Kemp has suggested. At any rate the evidence 

 is strong that very much if not all of the North Creek area was 

 covered by the late Cambric sea and probably also by the Ordovician 

 sea. The deposits made in those seas have all been removed by 

 erosion except for the small outlying masses above described. It is 

 important to note that each one of these outliers has been very con- 

 siderably faulted downward from the original position of the strata 

 and thus they have been ])rotected against com[)lete removal by ero- 

 sion during so many million years. 



STRl'CTl'RAL FFATURFS 



FAULTS 



General considerations. That the eastern Adirondacks are ex- 

 tensively faulted has been recognized for some years, but thus far 

 comparatively little attention has been t)aid to the detailed study 



