24 



The equivalent strata of the older and newer class- 

 ifications as used by Grabau and Schuchert respectively are 

 shown in parallel columns below: 



(Grabau) 



(Schuchert") 



Silurian 



Lockport (Niagara) limestone 

 Rochester (Niagara) shale 

 Clinton limestone, two beds 

 Clinton shale 

 Medina formation 



Upper Medina sandtone 



Medina sandy shales 

 Lower Medina gray shales 

 Medina gray, quartzose 

 Whirlpool sandstone 



Medina red shales 

 Oswego sandstone 



Silurian 



Lockport dolomite 



Rochester shale 



Clinton limestone, two beds 



Clinton shale 



Medina formation 

 Medina sandstone 



Cataract formation 



Cataract sandy shales 



Cataract gray shales 



Basal or Whirlpool sandstone 



Ordovician 



Queenston red shales 

 Oswego sandstone 



Ordovician 



The Lockport limestone is not rich in well preserved 

 fossils where exposed in the Niagara gorge, but Grabau 

 describes one of the lower beds of this foundation, the 

 Crinoidal limestone, as a "highly crystalline limestone, 

 on the weathered surfaces of which joints of crinoid stems 

 and other organisms stand out in relief, particularly 

 in the lower parts of the stratum. The rock is entirely 

 composed of fragments of organisms which were ground 

 up and mingled together in great profusion." The 

 Geodiferous limestone next above also contains fragmentary 

 fossils, but none well preserved. 



Grabau gives also a list of the few fossils found in the 

 Clinton upper limestone and 29 species found in the lime- 

 stone lenses in the Clinton shale. 



SUMMARY OF GORGE CHARACTERS AND 

 SECTIONS. 



If the study of the Niagara gorge were approached 

 without any previous knowledge of the history of the 

 great lakes, characters of some importance might possibly 

 be overlooked, but the larger variations of width and depth 

 would at once attract attention. From this point of view, 

 the characters clearly suggest a division of the gorge into 

 at least four sections, not including the whirlpool, and 



