Studies for Students' 



RELATIVE GEOLOGICAL IMPORTANCE OF CONTINEN- 

 TAL, LITTORAL, AND MARINE SEDIMENTATION 



JOSEPH BARRELL 



Yale University, New Haven, Conn. 



PART II 



The Regions OF Marine Sedimentation 430 



Extent and.Character OF THE Littoral Zone 433 



Observed Relation of Tides to the Littoral Zone 434 



Causes Restricting the Width of the Littoral Zone 438 



Conditions for Preserval of the Sedimentary Record 441 



Preserval of the Continental and Marine Records 441 



Conditions for Preserval of the Littoral Record 442 



Relations of Continental and Marine Sedimentation through 



Geological Time ■ . . . . 446 



General Applications to Geological History 449 



Pre-Cambrian ^on of Continental Extension 449 



Paleozoic Epicontinental Basins 452 



Mesozoic and Cenozoic Continental Deposits 457 



THE REGIONS OF MARINE SEDIMENTATION 



For the present purpose it is unnecessary to consider the deep 

 ocean deposits, or even the massive limestone formations, since the 

 discussion centers on the comparison of the areal extent and impor- 

 tance of the detrital deposits upon the land and beneath the sea. 



The investigations of the Challenger expedition^ showed that the 

 rubble, sand, and silt were practically limited to the upper 100 

 fathoms of the ocean bed, and that this corresponded rather closely 

 with the limits of the continental shelves. At about this depth the 

 bottom is in general rarely disturbed by the action of currents or 

 waves. Except in bays, fjords, and inclosed seas where mud is met 

 with in shallow water, it may be said that in general, fronting all 



1 Continued from p. 356. 



2 Murray, Deep Sea Deposits, p. 184. 



430 



