520 



C. SCHUCHERT PALEOGEOGRAPHY OF NORTH AMERICA 



These are likewise plentiful in Labrador, New Siberia, Spain, and Sar- 

 dinia. Such sponge-like corals in thick reefs suggest rather warm waters 

 and seem to indicate that the glacial occurrences had but little effect on 

 the oceans. That there was a change toward warmer waters throughout 

 the remainder of the Cambrian is shown by the far larger number and 

 variety of species, the greater abundance of lime-secreting animals, the 

 vaster number of individuals, and by the more and more persistent calca- 

 reous deposition of the seas. 



Acadic Period (new) 



(Middle Cambrian, Acadian, or Paradoxides epoch) 



See plate 52, and pages 483, 484 



Table of Acadic Formations 



House range, Utah 

 Walcott, 1908 



Weeks limestone 

 1,390 



Marjum limestone 

 1,102 



Wheeler shale 

 570 



Swasev limestone 

 340 



Dome- limestone 



355 

 Howell limestone 



435 



Spence shale 



20 

 Langston limestone 



205 



Mount Bos worth, 

 British Columbia 

 Walcott, 1908 



Eldon limeston; 



2,728 



Stephen shale and 



limestone 



640 



Cathedral lime- 

 stone 

 1.595 



New Brunswick 

 Matthew, 1896 

 Walcott, 1900 



? Break 



Saint Croix river of 

 Minnesota- Wisconsin 



Berkey, 1898 



■Break- 



Paradoxides dari- i Franconia glauco- 

 us zone nitic sandstone 

 100-200 

 Paradoxides aben- 

 acus zone 

 75 



Dresbach shale and 

 sandstone 

 150-200 

 Paradoxides ete- 

 minimis zone 

 25 



Paradoxides lamel- 

 latus zone 



Prololenus zone 

 108 



Lowest sandstones 

 0-1,000 



■Break- 



The Middle Cambrian in the Cordilleran sea appears to have continued 

 the Georgic seas without break, and early extended the invasion into 

 the Arctic ocean. The Pacific flood also transgressed the continent with 



