CLASSIFICATION OF MARINE DEPOSITS 713 



IV. Marine derelicts, or stragglers from other realms. These may be de- 

 posited in the Littoral, Bathyal, or Abyssal districts. 



A. Land-derived, either from continents or islands. 



1. Terrestrial, derived from the land: 



a. Organic — land plants or animals floating out to sea or rafted 

 seaward (as under o) and deposited in the Littoral, Bath- 

 yal, or Abyssal districts. (Microorganisms blown out to 

 sea with the dust would also be classed here.) 



h. Inorganic — rocks, sand, gravel, etcetera, rafted from land 

 and deposited in the Littoral, Bathyal, or Abyssal districts. 

 According to the method of transport, we have: 



(1) plant rafted — rocks, etcetera, held by roots of float- 



ing trees, etcetera. 



(2) animal rafted — stones in stomach of modern sharks 



and seals, and of Jurassic Mystriosaurus and Ple- 

 siosaurus, 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) wind rafted — wind-blown dust or sand, and volcanic 



material 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 car- 

 ried 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 tem- 

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

 cases of organisms, such as sea-birds, 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 Subcrustal origin. 



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

 so that both pyrogen ics and pyrocla sties flow or are projected into 

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

 ported pyroclastics. 



Discussion 



Prof. J. Barrell: A classification makes for sharpness of thought and must 

 precede analysis, so that I am in general sympathy with Professor Grabau on 

 the purpose and propositions of his paper "A classification of marine deposits," 

 but I wish to make a few comments on details. 



There is objection to the use of the word "littoral" in the vague sense here 



