24 



NEW YORK STATE MUSEUM 



FORMATION 



o H 



U (U 



O w 



m 



Ogdensburg formation 



oq 



Tribes Hill formation 



Theresa formation 



Potsdam formation 



Grenville series and 

 igneous rocks 



Oo 



Ot 



Cp 



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)IQQI0010Q1' 



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I I IT 



rrzi 



I , I r 



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V*-^ai^^<^<-^U^^^ 



III': 



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i ' l ' l' l ' I 



111 ~r~T 



1-^ 



I20' + 



(20') 



o-6o' 



CHARACTER OF FORMATION 



Alternating beds of massive, 

 blue-gray, granular dolo- 

 mite, and thin-bedded, 

 iron-gray, fine-grained 

 dolomite: with an occa- 

 sional bed of gray, calcare- 

 ous sandstone 



Thin-bedded, blue, sandy 

 limestones above and be- 

 low, with an intermediate, 

 more sandy member 



Alternating beds of white 

 sandstone, gray calcareous 

 sandstone, and blue sandy 

 limestone, with a 20' sand- 

 stone member, the Heu- 

 velton sandstone, near the 

 summit 



Mostly white, vitreous sand 

 stone 



Fig. I Generalized columnar section of the rocks of the Brier Hil], Ogdensburg 

 and Red Mills quadrangles 



Character of the Precambrian surface under the Paleozoics. 



It has been shown in many of the recent New York reports that 

 Paleozoic deposition commenced upon a Precambrian surface 

 which was characterized by considerable irregularity. This irregu- 

 larity seems to have been most pronounced on the northeastern 

 margin of the Adirondacks, in Clinton county, and to diminish in 

 amount both to the south and to the west. On the southwest, in 



