238 CONFERENCE ON PALEOZOIC PALEOGEOGRAPHY 



PHYSICAL CONDITIONS UNDER WHICH PALEOZOIC CORAL REEFS WERE 



FORMED 1 



BY THOMAS WAYLAND VAUGHAN 



CONTENTS 



Page 



Definition and origin of coral reef 238 



Recent coral reefs 239 



Composition • 239 



Depth of water and intensity of light 239 



Temperature ^ 240 



Motion of the water 242 



Character of the bottom 242 



Composition of the oceanic salts - 242 



Specific gravity of the water 243 



Paleozoic coral reefs ^ 248 



In general , 243 



Caml^rian 244 



North America 244 



Other lands 244 



Ordovician 244 



North America 244 



Silurian 244 



North America 244 



. Europe 244 



Devonian 245 



North America ^ 245 



Europe 245 



Carboniferous 245 



North America 245 



Europe 245 



Depth of water and intensity of light 248 



Temperature 250 



Movement of oceanic waters ? 250 



Character of the bottom 250 



Composition of the oceanic salts 250 



Specific gravity 251 



Summary 251 



Definition and origin of Coral Eeef 



A coral reef is a ridge or mound of limestone, the upper surface of 

 which lies, or lay at the time of its formation, near the level of the sea, 

 and is predominantly composed of calcium carbonate secreted by organ- 

 isms, of which the most important are corals. A coral reef is, therefore. 



1 Manuscript received by the Secretary of the Society May 23, 1911. 

 Published by permission of the Director of the United States National Museum. 



