MARINE HYDROCLASTICS 



643 



SUBDIVISIONS OF THE AREAS OF MARINE DEPOSI- 

 TION. TYPES OF iMARINE DEPOSITS. 



The following districts and zones or regions of deposition of 

 clastic material may be recognized in the sea : 



1. The Littoral District, or that ranging from the shore to the 

 edge of the continental shelf, that portion of mediterraneans corre- 

 sponding to this, and the whole of the bottoms of epicontinental 

 seas. Deposits formed here are "littoral deposits," and they are 

 among the most varied of their kind. The littoral district is divisi- 

 ble into the shore zone between tides and the permanently sub- 

 merged shallow water or ncritic zone* {FlacJiscc), extending to 

 the isobath of 200 meters. 



2. The Bathyal District (Renevier) is that district lying between 

 the outer limit of the neritic zone, i. e., the 200-meter line, and ap- 

 proximately the isobath of 900, or, in round numbers, i.ooo meters. 

 It represents the steep slope from the edge of the continental shelf 

 to the point of decreasing angle of slope. This comprises only the 

 upper portion of Penck's aktic region, which extends to the mean 

 sphere level of 2,400 meters below sea-level (see Chapter I). (Fig. 



I, p. 8.) 



3. The Deep Sea or Abyssal District. This, according to Penck 

 and others, begins at the 2,400-meter line, but so far as deposition is 

 concerned begins practically at the 1,000-meter isobath. 



A general classification of oceanic sediments, including all types, 

 was made by Murray and Renard (62: 186), as follows: 



ATitrray and Renard' s Classification of Marine Deposits. 



I. Deep-sea deposits beyond 

 100 fathoms 



2. Shallow-water deposits be- 

 tween low-water mark and 

 100 fathoms 



3. Littoral deposits between 

 high and low-water marks. 



Red clay 

 Radiolarian ooze 

 Diatom ooze 

 Globigerina ooze 

 Pteropod ooze 

 Blue mud 

 Red mud 

 Volcanic mud 

 Coral mud 



Sand, gravels, 

 muds, etc. 



Sands, gravels, 

 muds, etc. 



I. Pelagic deposits form- 

 ^ ed in deep water re- 

 moved from land 



II. Terrigenous deposits 

 formed in deep and 

 shallow water, mostly 

 close to land 



* Haug (43:5(5) and others have shown a tendency to use ncritic in the sense 

 in which littoral is here used, restricting that term to the shore zone or inter- 

 cotidal region. The use here advocated seems the most serviceable. 



