10 



BULLETIN 55, UNITED STATES NATIONAL MUSEUM, 



DEPOSITS. 



The accepted classification of marine deposits, by Dr. John Murray 

 and Dr. A. F. Renard/' is as follows: 



1. Deep-sea deposits be- 

 yond 100 fathoms. 



2. Shallow - water de- 

 posits between low-water 

 mark and 100 fathoms. 



3. Littoral deposits be- 

 tween high and low water 

 marks. 



Marine deposits. 



Red clay. 

 Eadiolarian ooze. 

 Diatom ooze. 

 Globigerina ooze. 

 Pterapod ooze. 

 Blue mud. 

 Red mud. 

 Green mud. 

 Volcanic mud. 

 Coral mud. 



Sands, gravels, muds, etc. 



Sands, gravels, muds, etc. 



Pelagic deposits formed in 

 deep water removed from 

 land. 



Terrigenous deposits 

 formed in deep and shal- 

 low water close to land 

 masses. 



Only 22 soundings are recorded within the 100-fathom line, and from 

 several of these no specimens have come to hand. Practically, there- 

 fore, only deep-sea deposits have to be considered in this report. 



lied clay. — Of the above-mentioned classes of deposits by far the 

 most extensive is red cla3^ This, as it appears in the specimens 

 received, is a smooth, sticky mud, varying in color from light yellowish- 

 brown (fawn color) to dark chocolate, these colors being somewhat 

 modified in individual instances by exposure to light, and especiall}^ 

 b}^ drying. In composition it consists of (1) extremely fine, amorphous 

 particles of cla3^ey matter, mosth^ hydrated aluminum silicate and the 

 debris of other minerals; (2) the remains of calcareous organisms 

 (f oraminif era, coccospheres, and rhabdospheres), this constituent, how- 

 ever, rapidly disappearing at depths of about 2, 500 fathoms; (3) siliceous 

 organic remains (sponge spicules, radiolarian skeletons, and the frus- 

 tulesof diatoms; (4) mineral fragments, mostly of volcanic origin, at 

 least in this part of the ocean; and (5) certain products of local chem- 

 ical reactions, especially nodules, coatings, and grains of manganese 

 peroxide, crystals of phillipsite, and particles of palagonite. The pro- 

 portions of these constituents vary greath" along the line and even 

 from station to station. As has been stated, foraminif era disappear, 

 for the most part, at depths below 2,500 fathoms; radiolaria are likely 

 to be more numerous in the deeper waters; diatoms are nearl}^ ever}^- 

 where, but only occasionally in great numbers. Mineral fragments 

 may be so minute in some specimens that they pass over almost 



« Report on Deep Sea Deposits, based on specimens collected during the voyage of 

 H. M. S. Challenger. 



