DEVONIAN. 291 



Generalized section of the Devonian heds of Milwaukee, Wis. 



Feet. 



Black shale 15 



Soft bluish ''soapy clay" or shale 80 



Bluish magnesian limestone, "cement rock '' 12 



Bluish limestone.and softer bluish "soapy clay " 31 



These beds, with the exception, of the upper black shale, are highly fossUiferous, showing 

 a great variety of invertebrate forms as well as plates and teeth of armor-plated fishes. 



* * * Beneath this group of beds is the brownish limestone provisionally referred to the 

 Cayuga group [Waubakee formation, Silurian]. 



K 17. ONTARIO. 



In Ontario the Devonian formations, as determined by boring, are listed by 

 Brummel '''^°' as follows: 



Devonian: Feet. 



Portage and Chemung 25-200 



Hamilton , about 350 



Comiferous 160-300 



Oriskany 6-25 



Silurian: 



Lower Helderberg l 



„ , 300-1,000 



Onondaga J 



These formations, their distribution, and their relations to the New York 

 equivalents as then understood were described in detail by Logan. ^^ Concerning 

 the Oriskany he states that it enters Canada at Waterloo, on the Niagara. 



.In its lithological characters it does not seem to differ materially from the same rock in 

 New York. The lower beds appear in several places to be composed of chert or hornstone, 

 frequently containing large quantities of iron pyrites, and. occasionally beautiful specimens of 

 purple fluorspar. * * * Resting on these beds there is a sandstone, which is somewhat 

 different in different localities. In the township of Dunn, near Haldimand, it is frequently 

 made up of large angular pieces of hornstone; which, with the numerous large corallines and 

 other fossils present, render it almost useless as a building stone. In the townships of Oneida 

 and North Cayuga * * * there are large exposures of the rock. It is composed of fine 

 grains of white quartz, in some parts so closely cemented as to assume the characters of a white 

 compact quartzite. In other parts it is made up of coarser grains of quartz, some of thena 

 being an eighth of an inch in diameter and pretty well rounded. With these there are occasion- 

 ally grains of feldspar. The rock in these cases, being sometimes slightly calcareous, disin- 

 tegrates by exposure to the weather. The beds are massive and from 6 inches to 6 feet thick. 



* * * The sandstone in some parts very much resembles the white beds of the Potsdam 

 formation; but it passes from white to fight gray and, in some places, through yellowish to 

 brown. * * * The greatest thickness of the mass may be about 25 feet; but though now 

 and then attaining 10 feet, it seldom exceeds about 6, and it is frequently wanting between the 

 Waterhme series and the overlying Corniferous formation. 



The rock abounds in organic remains." 



Concerning the "Corniferous" Logan states: 



In western Canada we find that many of the fossils of the Corniferous limestone pass up 

 from the Oriskany sandstone; and the intermediate Onondaga limestone, with its encrinites, can 

 no longer be recognized as a distinct formation. We therefore unite the two limestones under 

 the name of the Corniferous formation. 



= For list of species see the work cited. — B. W. 



