MARINE BOTTOM SAMPLES OF LAST CRUISE OF CARNEGIE 



Types of Marine Deposits 



The limiting characteristics of the types of deep-sea 

 marine deposits as they were distinguished by Murray 

 and his co-workers are summarized in the accompany- 

 ing table (table A). For each deposit type, the CaC03 

 content, per cent of pelagic and benthonic foraminifera 

 and other calcareous remains, per cent of siliceous re- 

 mains, and texture and composition of inorganic constit- 

 uents are listed. These have been taken from the sum- 

 maries given by Murray and Rfinard for the Challenger 

 samples, by Murray and Philippi (1908) for the Valdivia 

 expedition, and by Murray and Chumley (1924) for over 

 1400 deposits of the Atlantic Ocean. The actual CaCOa 

 content of a sample was chemically determined by these 

 authors, whereas the relative proportions in the whole 

 sample of pelagic and benthonic foraminifera and of cal- 

 careous remains other than foraminifera were estimated 

 by inspection chiefly of those parts of the sample great- 

 er than 0.05 mm in size. This procedure has been ques- 

 tioned by Heim (1924), who points out that samples listed 

 by Murray and his co-workers as containing from 40 to 

 70 per cent pelagic foraminifera actually often contain 

 only 1 to 5 per cent of recognizable tests of foraminifera. 

 In the Challenger report, the percentage of remains of 

 siliceous organisms included only those greater than 

 0.05 mm in size. Later, the procedure for estimating 

 the proportion of siliceous remains was revised, and the 

 estimated amounts in the finer fractions were included 

 in the total percentage of siliceous remains by Murray 

 and Chumley. 



Following is a list of the various types of deep-sea 

 marine deposits of Murray and Rinar"d, arranged alpha- 

 betically, together with a discussion of the origin of the 

 terms used and of names applied to similar deposits by 

 other workers. Later it will be shown that certain re- 

 visions of the existing terminology may be desirable in 

 order to obtain greater precision in the classification 

 and separation of deep-sea sediments. 



1. Blue mud (French, Boue bleue; German, Blauer 

 Schlick). This name was employed by Murray in 1876 to 

 designate the deposits most frequently met with in the 

 deeper waters surrounding continental land and in all 

 enclosed or partially enclosed seas more or less cut off 

 from free communication with the open ocean. The 

 terms "gray mud" (for noncalcareous samples) and 

 "transition mud" (for samples containing appreciable 

 amounts of lime) were suggested by Schmelck (1882) 

 and later employed by Bogglld (1906). The blue muds 

 are characteristically slatey or bluish in color when wet, 

 passing in most cases into a more or less thin layer of 

 a reddish color at the upper surface. In some of the 

 samples collected by the Siboga expedition this layer 

 was 15 cm in thickness (BSggild, 1916). When dry, the 

 great majority of Atlantic samples are gray, sometimes 

 with a brown, green, or blue tinge, and sometimes brown 

 or reddish rather than gray. The structure is rarely 

 plastic and compact, but instead is usually only moder- 

 ately coherent and granular. In blue muds of glacial or- 

 igin theproportionof clay minerals in the finer fractions 

 may be quite small, and these deposits were designated 

 as glacial marine sediments by Philippi. Coprolitic 

 pellets are common, and phosphate nodules rare, con- 

 stituents of blue muds. When the former are abundant, 

 the term coprolitic mud employed by Buchanan (1890) 

 may be used (see Murray and Philippi [1908], Andr6e 

 [1920], and Thorp [1931]). 



2. The terms coral mud and coral sand were em- 

 ployed by Murray and Renard in 1884 to designate the 

 calcareous sediments found in the vicinity of coral reefs 

 and islands, and consisting largely of the fragments of 

 neritic and benthonic organisms. Since the remains of 

 corals are usually not predominant constituents of such 

 sediments, Murray and Philippi (1908) later suggested 

 the use of the term "Detritogene Kalkablagerungen," 

 and Vaughan (1924) used the terms "calcareous muds 

 and sands." These deposits are usually white or dirty 

 white in color. The large amount of fine-grained cal- 

 careous matter in calcareous muds gives them a sticky 

 and chalky character, according to Murray and R6nard, 

 whereas calcareous sands, which, as the name implies, 

 are sandy in texture, are incoherent and granular in 

 structure. (For more detailed descriptions of these de- 

 posits, see Goldman [1926], Bramlette[1926], and Thorp 

 [1935]). 



3. Diatom ooze (French, Vase a diatomee; German, 

 Diatomeenschlamm). This term was introduced by Mur- 

 ray in 1876 to distinguish those deposits first described 

 by Hooker (1847) from the Antarctic in which diatom 

 frustules are exceptionally abundant. Such deposits are 

 characteristic of the cold waters of the Southern Ocean 

 at a distance from the Antarctic Continent and are found 

 also along the northern border of the Pacific. They are 

 characteristically yellowish, straw or cream colored 

 when wet, and dirty white when dry, although according 

 to Murray and Renard near land they may assume a 

 bluish tinge from the admixture of land detritus. ^ When 

 dry, the deposits are pulverulent, soft, and gritty in 

 structure. 



4. Globigerina ooze (French, Vase i Globigerines; 

 German, Globigerinenschlamm). Globigerina ooze was 

 described first by Bailey in 1853 (see Maury, 1859) and 

 by Ehrenberg (1854) from specimens collected by Lee 

 and Berryman of the United States Navy in the north At- 

 lantic. This deposit covers most of the great central 

 oceanic basins at depths less than 2500 fathoms, and is 

 second in areal distribution only to red clay. The color 

 of Globigerina oozes far from land is said to be milky 

 white, rose, yellow, or brown and of that near land dirty 

 white, blue, or gray. The structure is usually pulverulent- 

 granular to coherent, and the deposits are usually fine- 

 grained and homogeneous, though in the tropics many of 

 the foraminifera shells present in the deposits are mac- 

 roscopic in size. As stated above, proportions of the 

 various calcareous organisms given in the table were 

 estimated from the coarser fractions of the sediments 

 which were assumed to be representative of the finer 

 fractions as well. On the other hand, Lohmann (1903) 

 describes a sample from the Atlantic which contained 70 

 per cent of coccoliths and Andree points out that this 

 should be designated as coccolith ooze. Certain of the 

 Challenger samples redescribed by Heim in which "die 

 Hauptmasse besteht aus mehr oder weniger tonreichem 

 dichtem KaUcschlamm, der die grosste Ahnlichkeit mit 

 Seekreide hat" (Pia, 1933, p. 339) might logically be 

 called simply calcium carbonate oozes, since it is often 

 impossible to determine what organisms, if any, were 

 responsible for the deposition of the larger proportion 



^Since this was written, a paper by Neaverson (1934) 

 on the bottom deposits collected by the Discovery II and 

 William Scoresby has appeared in which the term diato- 

 maceous mud is suggested for diatomaceous sediments 

 which contain considerable amounts of detrital mineral 

 grains and of decomposable organic matter. 



