646 . PRINCIPLES OF STRATIGRAPHY 



a Organic: land plants or animals floating out to sea or rafted 

 seaward (as under b) and deposited in the Littoral, Bathyal 

 or Abyssal districts. (Microorganisms blown out to sea with 

 the dust would also be classed here.) 



b Inorganic: rocks, sand, gravel, etc., rafted from land and deposit- 

 ed in the Littoral, Bathyal or Abyssal districts. According to 

 the method of transport we have: 

 (i) plant rafted: rocks, etc., held by'roots of floating trees etc. 



(2) animal rafted: stones in stomachs of modern sharks, and 

 seals, and of Jurassic Mystriosaurus and Plesiosaurus as 

 well as in the stomachs of many land animals which may 

 float out to sea 



(3) ice rafted: by icebergs and floating ice cakes 



(4) tvind rafted: wind-blown dust or sand, and volcanic ma- 

 terial brought from the land 



(5) ship rafted: substances carried out by ships or man-made 

 rafts and cast overboard or deposited on the foundering 

 of the ship 



(6) carried into the sea by slipping or gliding 



2 Aquatic: derived from the rivers and estuaries. This would comprise 

 chiefly river animals and plants which have been carried out to sea 



3 Derived from adjacent higher zone by gliding or thrusting 

 B Atmospherically derived 



Since the chief atmogenic solids, snow and hail, have only a temporary 

 existence, deposits from this source may be neglected. Rare cases 

 of organisms, such as seabirds, which spend most of their lives in the 

 air, might perhaps be included here, but they may as well be classed 

 with terrestrial derelicts 



C Meteoric — of Extratelluric origin 



Here belong the cosmic dust and the meteorites 



D Of Subcriistal Origin 



This includes volcanic eruptions beneath the sea and on the coast, 

 so that both pyrogenics and pyroclastics flow or are projected into 

 the sea. The direct pyroclastics merge of course into the wind-trans- 

 ported pyroclastics 



DISCUSSION OF THE MARINE CLASTICS. 



In the following pages the clastic deposits will be discussed with 

 reference to the regions in which they are deposited. Lacustrine 

 elastics will be repeatedly used for parallel illustrations. 



The Littoral District and Its Deposits. 



The term littoral zone is frequently restricted to the part be- 

 tween high and low- water mark, i. e., the shore, while the term 

 neritic has recently come into use for that portion between low 

 water and the edge of the continental shelf. The term littoral dis' 



