244 conference on paleozoic paleogeography 



Paleozoic Coral Eeefs^ 

 in general 



The following sketch of Paleozoic reefs is very general, and is in- 

 tended merely to indicate their wide stratigraphic and geographic dis- 

 tribution, at the same time mentioning a few of the more abundant 

 types and facies of reef-forming organisms. 



CAMBRIAN 



North America. — In the lower Cambrian the Archceocyathince form 

 banks of reef-like character in Newfoundland, California, and Nevada. 

 There are, in a zone comprising a part of the upper Cambrian and the 

 lower part of the Calciferous in New York, Pennsylvania, Virginia, Ten- 

 nessee, Missouri, Wyoming, and Alaska, reefs predominantly composed 

 of Cryptozoon. 



Other lands. — Outside of North America the ArchcBocyathinoe are 

 found in Sardinia, Spain, northern Scotland, northern Siberia, and 

 Australia. 



ORDOVIGIAN 



North America. — Eeefs of Cryptozoon minnesotensis occur in the 

 lower part of the Canadian group, in Vermont, New York, Alabama, 

 Arkansas, and Minnesota. In the Chazy group reefs are formed by 

 Stromatocerium and Stylaroea in New York, Tennessee, Kentucky, and 

 Oklahoma; in the Black Eiver, by Stromatocerium, Columnaria, Tetra- 

 dium, and Halysites in Canada, New York, along the Appalachian Val- 

 ley to Alabama, in Kentucky, Tennessee, Missouri, Wisconsin, and Min- 

 nesota; in the Trenton group, by Stromatocerium, Oolumnaria, and 

 Tetradium in Tennessee and Kentucky; in the Cincinnatian, by Stro- 

 matocerium, Columnaria, and Tetradium in Tennessee and south central 

 Kentucky. In the Eichmond group there are reefs composed of Stro- 

 matocerium, Columnaria, Tetradium, Beatricia, Labechia, Calapoecia, 

 Favosites, Halysites, and Heliolites in Baffin Land, Anticosti, northern 

 Michigan, Illinois, Indiana, Kentucky, Tennessee, Texas, Oklahoma, 

 Arkansas, Missouri, Colorado, Nevada, Wyoming, and Alaska. 



SILURIAN 



North America. — In the Niagaran group reefs are formed by Stromato- 

 poroids, Favosites, Halysites, Heliolites, Lyellia, Zaphrentis, and Cyatho- 



'' This account of Paleozoic coral reefs is based mostly on oral information received 

 from Mr. E. O. IJlricli, Freeh's "Ueber Korallenriffe und ihrem Anteil an dem Aufbau 

 der Erdrinde," Himmel und Erde., Bd. 9, 1897, p. 97 et seq. ; Zittel, Traite de Pal. t. i ; 

 Geikie's "Text-book of geology ;" Dana's "Manual of geology," and Grabau's "Paleozoic 

 coral reefs," Bull. Geol. Soc. America, vol. 14, 1903, pp. 337-352. 



