CLASSIFICATION OF MARINE DEPOSITS 645 



origin and next as to their mode of occurrence. Thus we may make 

 the following classification, taking oceanic deposits as a whole: 



A Nezv Classification of Marine Deposits. 



I Marine hydrogenics (halmyrogenic deposits) or chemical precipitates 



from the sea water. (These have been fully discussed in Chapter IX.) 



II Marine biogenics or organic deposits of marine origin 

 A Benthonic or living on sea bottom 



1 Littoral — -originating in littoral district 



a Shore zone 



(i) autochthonous or growing in situ 



(2) allochthonous or cast up from deeper water 

 b Neritic or shallow water zone 



(i) autochthonous — ^growing in situ 



(2) allochthonous — transported, usually from shore zone 



2 Bathyal 



( 1 ) autochthonous 



(2) allochthonous — transported, usually from littoral zone 



3 A byssal 



(i) autochthonous 



(2) allochthonous — -transported from the littoral or bathyal 

 regions 

 B Pelagic or living in the open ocean and its extension into the shore 

 indentations, either as plankton or nekton. (See Chapter XXVII.) 

 These may settle in the Littoral, Bathyal or Abyssal districts, remain- 

 ing either in place, or more or less rearranged or worked over, especially 

 in shallow water whence they niay be cast on shore and even blown 

 inland. 



III Marine clastics. Fragmental material worn off by or in the sea 



A Hydrcclastics — worn off or rearranged by the sea waves or currents 



1 Terrigenous or land-derived 



a from continent including continental islands 

 b from oceanic islands exclusive of coral reefs, and other organic 

 deposits 



2 Thalassigenous; or sea-derived 



a organic lime sand and mud derived from coral reefs, from 



nullipore reefs, shell deposits, etc. 

 b derived from halmyrogenic or chemical deposits. Clastic 

 material derived by destruction by waves of chemical deposits 

 formed by the sea (not known). Chemically formed marine 

 oolites when worn by waves may come under this head 

 B Bioclastics: rock material broken up by marine organisms 



Marine bioclastics. These may, according to the source from which 

 the material was originally derived, be classed as 



1 Terrigenous, from continents and islands 



2 Thalassigenous, from coral reefs, etc. 



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 

 I Terrestrial, derived from the land 



