398 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
white porcehiin basin; the acid in a few moments dissolves the particles and passes away in a dark- 
colored stream. 
In preserving samples for examination in the laboratory at home, the best method is to place the 
sample as procured in a glass bottle and to add a small quantity of spirits of wine. 
The various kinds of marine deposits belonging to the two great classes have been named from 
the relative abundance and character of the organic or inorganic materials of which they are corn- 
loosed. The following is the nomenclature adopted by Dr. John Murray after an examination of the 
samples procured in various regious of the ocean by the Challenger, the Tuscarora, the Albatross, and 
other deep-sea expeditions : 
I. Deep-so.a deijosits, beyond 100 fath- 
oms. 
II. Sliallow-water deposits, between low- 
water mark and 100 fathoms, 
III. Littor.al deposits, between high and 
low- water marks. 
Red clay ; Radiolarian ooze ; Iliatom ooze; \ 1. Pelagic deposits, formed in deep 
Globigerina ooze ; Pteropod ooze. ' — ’ ’ 
Blue mud ; red mud ; green mud ; volcaidc 
mud ; coral mud. 
I Sands, gravels, muds, etc. 
I Sands, gravels, muds, etc. 
water far removed from land. 
Terrigenous deposits, formed in 
deep and shallow water close to 
land masses. 
The term “ooze” is apidied only to pelagic deposits made up chiefly of the remains of organisms, the term “clay” 
only to tlie red clay found in the deepest regions of the ocean, and the terms “ mud ” and “sand ” only to terrigenous deposits. 
It is unnecessary to enter into details as regards the shallow-water deposits, but the following 
notes on the deeji-sea deposits, which term is applied to those from depths greater than 100 fathoms, 
may be appended : 
A. Pelagic Deposits. 
I. Bed claij. — This deposit is spread over the greater depths of the ocean remote from land, and 
is the most widely distrilmted and jjrobably the most characteristic of all deei)-sea deposits. The 
Challenger took 70 samples in depths ranging from 2,225 to 3,950 fathoms, the average dejith being 
2,730 fathoms. The Jlbatross investigations have shown that this deposit is spread over a wide area 
in the northeastern Pacific. The amount of clayey matter and the color vary greatly in diti'erent 
sami)les, but red is the prevailing color, sometimes brick red, sometimes dark chocolate, sometimes 
bluish or gray. The immediate upper layer is thin, watery, and often has a lighter color than the 
deeper layers, which are much more dense. 
The red clay is soft, plastic, and greasy to the touch. When dried it cakes into a hard, compact 
mass that can only be broken with the blow of a hammer. The hardened fragments assume a glazed 
a2)pearance and characteristic shining streak when rubbed briskly with the finger nail or any hard, 
smooth body. In the greater depths carbonate of lime may be almost, if not entirely, absent, while 
in lesser depths it may rise to over 20 per cent, and is due princixially to the remains of ])elagic for- 
aminifera, with a few coccoliths or rhabdoliths and other minute calcareous fragments. The remains 
of xielagic siliceous organisms are usually present, xirincipally radiolarians and diatoms, along with 
sxionge siiicnles and arenaceous foraminifera. 
The iirincixial mineral particles in a red clay are fragments of pumice and the mineral .species 
usually found in its different varieties. There may be also fragments of basaltic glass, basalt, augite, 
andesite, and x>alagonite arising from the decomxiosition of the basic volcanic glasses. The peroxides 
of iron and manganese are found throughout the red clays in the form of minute grains or coatings. 
AVhen dejmsited as concretions around organic remains and other nuclei, they form manganese nodules. 
In some red-clay areas thousands of sharks’ teeth and earbones of cetaceans, more or less imjiregnated 
or coated with manganese, have been dredged, and zeolitic crystals of secondary formation (phil- 
lixisite) and cosmic si>herules are sometimes met with. 
The origin of the red clay has been the subject of much discussion. It is evidently not a residue 
or ash derived from the solution of calcareous organisms, as supposed by Wyville Thomson, but is 
derived from the decouqiosition of aluminous silicates and rocks sjiread over the door of the ocean. 
Average composition of the Challenger samples of red clay. 
Carbonate of lime: 
Pelagic foraminifera 4.77 
Bottom-living foraminifera .19 
Other organisms 1.34 
6.70 
Residue : 
Siliceous organisms 2. 39 
Minerals 5.56 
Fine washings 85. .35 
93.30 
100 
