No. 3.] SPENCER — PALAEOZOIC GEOLOGY. 143 



V. — CLINTON FORMATION. 



In .«;outhern Herkimer County, N. Y., the Medina formution 

 i.s wanting, and the Clinton rests ou thin deposits of Oneida 

 congflonjerate, which itself dies out farther to the east. Id the 

 more eastern portions of the State of New York, where the 

 Clinton series succeeds the Medina, it partakes of its lithological 

 characteristics. However, as the Clinton extends westward its 

 shales become intercalated with calcareous deposits that form a 

 conspicuous feature. The calcareous beds increase in importance 

 as the formation! extends westward in the Province of Ontario, 

 and at Hamilton they so nearly resemble those of the overlying 

 Niagara, that the line of separation becomes almost arbitrary. 

 The New York Geologists placed a hard layer of dolomite, con- 

 taining remains of Pentamerus, and known as the '' Pentamerus 

 Band," as the upper bed of the Clinton of New York, while the 

 Canadian Geological Survey considered it as the lowest bed of 

 the Niagara series, which in our Province, it most nearly re- 

 st^mbles. The hitter division, between the Clinton and Niagara, 

 1 have adopted in this paper, if indeed, a division, except for 

 convenience, should be made. In fact, the upper nine ieet of 

 the Clinton deposits at Hamilton might well be placed with the 

 Niagara above. Nor are there any palgeontological grounds of 

 separation. 



The Clinton group may be described as dolomitic shales, with 

 numerous thin beds of argillo-arenaceous dolomites, some of which 

 almost resemble impure sandstone. The indurated shales are 

 generally of blue or dark gray, but in weathering they assume 

 a red, brown or buff color. Many of the more calcareous bands 

 are highly fossiliferous. About twenty feet trom the top of the 

 serie- there is a red or brown ferruginous calcareo-arenaceous 

 rock, about eight feet thick, holding an abundance of casts of 

 fos.^ils, vvhich are mostly of the genera Modiolopsis and Llngula. 



It may be here remarked that none of the LameUi branchiate 

 shells retain any part of their original tests, while the Lingulce 

 have their shells well preserved, and often of a blue color. 



This bed of red ferruginous rock is the representative of that 

 peculi.ir bed of oolitic iron ore, called "Fossil Ore," forming a 

 characteristic element of the Clinton group, extending from 

 Wisconsin to New York, and thence along the Appalachian 

 Chain to Tennessee and Alabama. In some places the " fossil 



