CLASSIFICATION AND FAUNAS 361 



About 47'5 species of fossils are known from these strata in Few York 

 and southern Ontario. With onr j^resent imj^erfect knowledge of the 

 range of these species (particnlarly in the Wolcott limestone), it is not 

 desirable to cumber these pages with an extensive tabulation by horizons ; 

 but an abbreviated summar}' by groups of strata will serve to show how 

 few species are known to pass the diastrophic barriers above indicated. 

 (The table aj)pears on the following page.) The surprising thing about 

 this table, however, is that the largest number of species in common be- 

 tween any two groups within the Eontaric is that between opposite ends, 

 the Eochester shale and the Cataract-Edgewood-Brassiield faunas — 23 

 species. This may have some paleogeographic meaning, or it may merely 

 measure our ignorance of what lies in between. The Eochester has its 

 largest quotas in common with the Niagaran faunas above it, whereas 

 the Cataract-Medina fauna shows less species in common with the entire 

 Ordovician (including Eichmond) than with the Eochester, and espe- 

 cially with the unquestioned ^NTiagaran (Lockport-Guelph, Louisville, 

 etcetera). The small Martville-Bear Creek fauna is more largely unique 

 (73 per cent) than any other (except the debated "Niagaran dolomite^' 

 of Hamilton, Ontario), and the large Eochester fauna stands next (67 per 

 cent unique). 



In confirmation of the deductions already made from the stratigraphy, 

 it should be noted that the typical "lower Clinton'' group (Furnaceville 

 to Wolcott Furnace), which carries the largest assemblage between the 

 Cataract and Eochester, has its fauna! affinities most decidedly with the 

 Cataract-Brassfield (23 per cent), whereas the overlying Williamson- 

 Brewerton-Phoenix division aligns itself equally decidedly with the Eoch- 

 ester shale in its faunal association (25 per cent). The current reference 

 of the Williamson Monograptus fauna to the lower Clinton has clearly 



i^aThe Gates probablj^ continues to thicken east of Rochester under the drift, and is 

 very likely the rock forming the falls at Wolcott village which Hall (2:82) speaks of 

 as the "higher heds" of his Niagara shale. 6 The Herkimer, supposed equivalent of the 

 Phoenix, is said to reach a maximum of 80 feet, c The iron ores (Donnelly, Wolcott 

 Furnace, Furnaceville) really are in the disconformity rather than above or below it, 

 since they represent concentrations of iron oxide during the depositional interruption ; 

 but their fossils are in general those of the adjoining limestone member. (I The supposed 

 equivalents of the Bear Creek and Martville forming the middle member of the Sauquoit 

 beds about Clinton and Utica have there a thickness of approximately 30 feet (2: 16). 

 e The beds correlated with the Maplewood likewise approach 50 feet thickness in the 

 Sauquoit syncline. f Should the "gray band" of Rochester prove distinct from the true 

 Thorold, the list will need to be amended at this point, g The Grimsby and Cataract 

 are equivalent beds of different facies, with contemporary overlap toward the west, as 

 interpreted by Schuchert (12 : 294) ; in Canada the Cataract eventually embraces the 

 entire interval, with a thickness equal to the sum of the measures here given, and is 

 there subdivided into the Manitoulin dolomite below and the Cabot Head shale above. 

 h The Whirlpool is considered by Frofessor Schuchert the basal member of the Cataract. 



