400 A. WJ GRABAU PALEOZOIC DELTA DEPOSITS OF NORTH AMERICA 



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The Medina beds of the Great Lakes region 459 



The Tuscarora 465 



The Clinch sandstone 467 



Summary of the early Siluric deposits 468 



The Niagaran marine interval 470 



The mid-Siluric delta fans of North America 472 



General discussion 472 



Details of the sections 476 



In general 476 



The Green Pond conglomerate and Longwood shale of the 



Paleozoic fault-block of New Jersey and eastern New York . 477 

 The Shawangunk formation of the Front Ridge of the north- 

 ern Appalachians 480 



The Longwood shales and sandstones 482 



The Keefer sandstone 485 



The McKenzie formation 486 



Other Salina beds of Pennsylvania 488 



Other Salina beds of New York 489 



Interpretation of the sections 492 



The Shawangunk conglomerates 492 



The argument from contemporary salt deposits and from the 



occurrence of Eurypterids 494 



The origin of salt deposits 496 



Relation of the Eurypterids to their environment.. 498 



Distribution and occurrence of the Eurypterids : Summary by M. 



O'Connell 499 



In general ,. 499 



Pre-Cambric 500 



Cambric 500 



Upper Ordovicic 501 



Summary for pre-Siluric 503 



Lower Siluric or Niagaran 504 



Middle Siluric or Salinan 506 



Upper Siluric or Monroan 508 



Devonic 513 



Post-Devonic 514 



Review of the evidence 515 



Conclusions regarding the origin of the Shawangunk and Long- 

 wood deposits , 526 



Introduction 

 river deposits 



In recent years it has come to be generally recognized that within the 

 stratigraphic series of both the old and the new world there are a number 





