OZARKIC OR CAMBRIC PERIOD 523 



embraces all the Arbuckle limestone to the top of its massive middle 

 member. 145 



In the southern Appalachians this period comprises considerable of the 

 Knox dolomite. According to Ulrich, the upper limit "is drawn at the 

 top of the main cherty mass of the Knox dolomite as exhibited in Copper 

 ridge," and the base begins "with the lower non-cherty member of the 

 Knox." In the middle Appalachians this time is represented within the 

 comprehensive Shenandoah limestone. In southern Pennsylvania by the 

 Conococheague formation. In New Jersey "the greater lower part of the 

 Kittatiny dolomite" is of this period. 



In New York and Canada the Ozarkic "is represented by the greater 

 lower part of the Little Falls dolomite, the Potsdam sandstone, the 

 Theresa formation and Division A, and B of Brainerd and Seely's Cham- 

 plain Valley Calciferous" (Ulrich; for further detail, see his paper in 

 the present volume) . 



In Minnesota and Wisconsin this period is manifested in the Shakopee, 

 New Eichmond sandstone, Oneota dolomite, Jordan or Madison sand- 

 stone, and the Saint Lawrence dolomites and shales. 146 



In the accompanying map the Lower Ozarkic or the Ozarkian trans- 

 gression is plotted at its maximum. It embraced the Lower Knox, Lower 

 Arbuckle, Lower Kittatiny, Elvins, Gasconade, Division A of Beekman- 

 town, Theresa, Little Falls, Potsdam, typical Saratogan, Saint Lawrence, 

 and Jordan or Madison. It is seen that the Mississippian sea derived 

 most of its life from the Gulf of Mexico, and distributed it far to the 

 northeast into the Saint Lawrence trough, yet is thought not to have 

 passed out here into the northern Atlantic. The faunas of New Bruns- 

 wick are wholly different, and are in harmony with those occurring in 

 Europe at this time. As there appears to have been some slight inter- 

 mingling of the Atlantic and the interior continental sea, a passage has 

 been opened into New Jersey. This exchange, if it existed, is not marked, 

 though later there was free communication between the two areas. 



As none of the later Ozarkic formations seem to have been present in 

 the Cordilleran sea, and possibly also none in Acadia, the Shakopee emer- 

 gence must have been of wide extent. The Mississippian sea was greatly 

 restricted in the northeast, and all the land here had emerged up to the 

 dotted line drawn on the map. As thus delimited, the Upper Ozarkic 

 comprised Oneota, Shakopee, Eoubidoux, Jefferson City, and the upper 

 part of the middle Knox. The emergence being continued, the Missis- 



145 Taffi : Professional Paper, no. 31, U. S. Geological Survey, 1904, pp. 22-23. 



146 Berkey : American Geologist, vol. 21, 1898, p. 377. 



