424 A. W. GRABAU PALEOZOIC DELTA DEPOSITS OF NORTH AMERICA 



of the deposit is shown near Collingwood, where some 770 feet of these 

 beds overlie the "Utica" shales above mentioned. These can be traced 

 northeastward to the Great Manitoulin Islands, where their thickness is 

 not over 50 feet. The highest beds of the "Hudson" series contain 

 Columnaria aiveolata, and with this, on the islands northwest of Cabots 

 Head, is associated Beatricea undulata. These fossils are good indi- 

 cators of the Richmond age of these higher beds, for in the Ohio region 

 Beatricea does not appear until the base of the Liberty beds, while the 

 coral occurs in the uppermost Eichmond (Madison or Elkhorn bed). 37 

 Both forms have a similar position in the Upper Eichmond of Anticosti. 



Overlying these Eichmondian beds on the Indian Peninsula are- red 

 and green shales, originally referred to the Medina. In the vicinity of 

 Cape Commodore they are 109 feet thick and are followed by about 36 

 feet of thin-bedded magnesian limestone, referred to the Clinton, above 

 which comes the Pentamerus bed of the western New York Clinton. At 

 Cabots Head, where the dolomites are 26 feet thick, and at Owen Sound, 

 where they are 20 feet thick, they contain Leptama rliomboidalis, Dal- 

 manella cf. testudinaria, Stenopora fibrosa Billings (= ? Eridotrypa tren- 

 tonensis (Nicholson) [Foord], a Trenton species), Strophomena pecten 

 (= Scliuchertella subplana), Orthis davidsoni, Anoplotheca planocon- 

 vexa, Favosites gothlandica, and others. This is a basal Siluric fauna 

 similar to or earlier than that found in Wisconsin. Overlying these dolo- 

 mites at Cabots Head are "103 feet of red marly sandstones, partially 

 striped and spotted with green, and interstratified with beds of red and 

 green argillaceous shale, some of which exceed 6 or 8 inches in thick- 

 ness." 38 The green argillaceous beds appear to be free from calcareous 

 matter. The series is followed by about 55 feet of green calcareous- 

 argillaceous shales and thin-bedded limestones, and terminated by the 

 massive limestone of the Niagaran series, which, here as elsewhere in this 

 part of Canada, begins with the Pentamerus bed, equivalent to the Wal- 

 cott limestone of New York. Ilelop.ora fragilis, which abounds in the 

 lower true Medina at Niagara and in the Clinton iron ore at Eochester, 

 also occurs in an impure hematite bed in the upper red beds. Ptilodictya 

 (Phwnopora) explanata, another Clinton form, also occurs here. 



As will be more fully shown later on, there is excellent reason for be- 

 lieving that the lower 109 feet of red and green shales resting on the 

 Eichmond of the Indian Peninsula represent the westward extension of 



37 J. M. Nickles : Richmond Group in Ohio and Indiana. American Geologist, vol. 

 xxxii, p. 213 (202-218). 



Schuchert : Paleogeography of North America. Bull. Geol. Soc. Am., vol. 20, p. 530. 



38 Logan : Geology of Canada, 1863. 



