144 THE CANADIAN NATURALIST. [Vol. X. 



ore " is only represented by ferruginous stains on tlie rock. This 

 iron niJitter came probably from the denudation of the exten- 

 sive iron ore deposits, Huronian Age, just north of the Clinton 

 sea, in what is now Michigan. 



The lower nine feet of the Clinton beds are composed of argil- 

 l.iceous dolomites with shaly partings, which are sometimes 

 bituminous. Some of these layers are so granular and arenace- 

 ous as almost to resemble sandstones. From the few fossils 

 obtained here, these rocks may be considered as beds of passage 

 from the Medina. Including the beds that I have placed as 

 beds of passage at the base and those at the summit of the Clin- 

 ton formation, the whole thickness at Hamilton is 94 feet, and 

 at Dundas 88 feet. 



In New York, on the Genesee River, the Clinton group has a 

 thickness of 80 feet, consisting of calcareous shales with thin 

 beds of shaly dolomite, together with the characteristic Oolitic 

 iron ore bed. 



In Ohio this formation is ropresetited by salmon-colored dolo- 

 mitic limestones which vary in thickness from 15 to 40 feet. 



As has been noticed, the Clinton deposits lithologically re- 

 semble those of the Medina, in eastern New York, while in the 

 western part of the State, they approximate to the overlying 

 Niagara. This resemblance is still greater in Canada, where 

 much of the shaly matter is replaced by calcareous rocks, and 

 in Ohio, according to the Geological Survey of that State, the 

 argillaceous beds are wholly replaced by limestones. Again 

 those differences in the fossils which characterise the respective 

 Clinton and Niagara formations in eastern New York largely 

 dis.ippear in the more western deposits. In Canada the palseon- 

 tological differences seem to be due to the state of preservation of 

 oijiauic remains in the shales and limestones respectively ; for the 

 forms which occur in the Clinton limestones are generally found 

 in the calcareous rocks of the overlying Niagara, whilst the prin- 

 cipal differences are in tiiose fossils preserved in the Clinton 

 shales, which are not represented above by similar rocks. In 

 fact there is no more variation in the fossils i'ound in the Clinton 

 and Niagara formations at H'milton than there is between those 

 of the Niagara *' Chert Bed " at Hamilton and of the upper layers 

 at Barton, five miles distant. 



Professor Orton found that the Clinton of Ohio contains 

 pebbles of the " Cincinnati (Hudson River) limestones." In 



