OF CENTRAL CANADA PART V. 



325 



between Lake Erie and Lake Huron, but the only known exposures 

 are in the Lake Erie townships of Bertie and Cayuga. 



The Oriskany Formation, the first in ascending order of the Devo- 

 nian series, is also but sparingly present in the district. It is 

 represented chiefly by a layer of chert or hornstone (containing 

 much iron pyrites) at the base, with a succeeding brecciated bed 

 (made up in part of chert fragments), and some quartzose grits or 

 sandstones : the entire thickness varying from about six to ten feet. 

 Its fossils are chiefly identical with those of the overlying Corni- 

 ferous strata, but are mixed in places with Upper Silurian types. 

 Some of the more common comprise : Favosifes Gothlandica (fig. 137); 

 Zaphrentis prolifica (fig. 144) ; Strophomena rhomboidalis (fig. 195); 

 Atrypa reticularis (fig. 188) and Calymene Blumenbachii (fig. 178\ 

 The formation enters Canada in the township of Bertie in the 

 north-east corner of Lake Erie, and appears to run as a thin band 

 along the southern edge of the Eurypterus or Onondaga formation at 

 least as far as the country of Norfolk ; but the only known exposures 

 occur at Bertie, Dunn, North Cayuga, Oneida, ;md Windham. From 

 the exposure in North Cayuga, a little north of the Talbot Road, 

 good millstones have been quarried. 



The Corniferous Formation, as recognized in Western Canada, 

 includes the " Onondaga limestone" and "Corniferous limestone" of 

 New York geologists. It is made up essentially of more or less 

 bituminous limestones, containing, in places, nodular masses of chert, 

 or interstratined with bands of that substance, and associated here 

 and there with beds of calcareous sandstone and bituminous shale. 

 The thickness of these strata, collectively, is estimated at about 200 

 feet. The limestones contain, as a rule, a great abundance of silici- 

 fied fossils, mostly brachiopods, corals, and crinoidal stems. The 

 common forms comprise : The corals, Michelinea convexa (fig. 138) ; 

 Syringopora Maclurei (with coarse cell-tubes, fig. 140) and S. Hisin- 

 geri (with narrow-cells, fig. 141); and the simple horn-shaped types ? 

 Zaphrentis prolifica (fig. 144) and Z. gigantea, the latter often a 

 couple of inches in diameter and five or six inches in length. The 

 bracuiopods, Strophomena rhomboidalis (tig. 195); Atrypa reticularis 

 (fig. 188) ; Spirifer mucronatus (fig. 185) ; S. gregarius (fig. 184 bin) ; 

 Spirigera concentrica (fig. 187) and Stricklandia elongata most of 

 which occur also in higher Devonian strata. The trilobite Phacops 



