46 



MARINE BOTTOM SAMPLES OF LAST CRUISE OF CARNEGIE 



When moist, red clays are usually moderately plastic 

 to plastic, moderately coherent to coherent, and some- 

 times slightly sticky; when dry they are usually coher- 

 ent and brittle. Macroscopic elements are only rarely 

 present. Fine-grained terrigenous deposits or muds 

 when moist or wet are slightly to moderately coherent, 

 sticky, and sometimes crumbly. These terms also apply 

 to siliceous oozes. Globigerina oozes are usually only 

 slightly coherent, crumbly, and granular when moist, and 

 moderately coherent to incoherent, crumbly, and granu- 

 lar when dry. 



Organic Constituents of the Samples 



Plant Remains . The plant remains in the samples 

 are of three kinds, namely (1) coccoliths and rhabdoliths, 

 the skeletal plates of Coccolithophores and Rhabdo- 

 spheres, (2) the frustules of diatoms, and (3) calcareous 

 algae. Coccoliths and rhabdoliths are usually present in 

 small amounts in the silt fractions of Globigerina oozes. 

 A horseshoe-shaped form was the principal type ob- 

 served. Diatoms are the predominant organic constitu- 

 ents of samples 59 and 60 in the northwest Pacific and 

 make up large amounts of the other siliceous oozes from 

 that region, as well as of the noncalcareous samples off 

 the coast of South America. Traces of diatom frustules 

 ai-e always present in siliceous oozes even when these 

 are highly calcareous. Remains of Corallinaceae and 

 Halimeda were observed in only one sample, number 29, 

 collected from the top of the Merriam Ridge. 



Foraminifera . Some of the specimens of foramini- 

 fera from sixteen samples were picked out, mounted on 

 cardboard slides, and sent for identification to Dr. J. A. 

 Cushman, who kindly undertook to determine the species 

 of those forms which could be readily identified. With 

 the aid of his determinations the writer then identified 

 many of the species in several other samples. The re- 

 sults, together with the order of abundance of various 

 species, are given in table 5 (pp. 48-55). At the time the 

 specimens were sent to Dr. Cushman he had not yet 

 completed the study of the family Anomaliidae from the 

 tropical Pacific collections of the Albatross (see U.S.N.M. 

 Bull. 161), and was consequently unable to give a report 

 on most of the species of this group in the collection. 



Although for this and other reasons the results are 

 far from complete, one hundred and forty -two species, 

 not including most of the Anomaliidae but including those 

 specimens listed merely as manuscript species or sp(?), 

 are listed. This is a minimum estimate, as in many 

 cases more than one species is represented in the latter 

 categories. Fifty-six genera are present. Of these, 

 eight are pelagic, seventeen are arenaceous benthonic, 

 and thirty -one are calcareous benthonic genera, the total 

 number of benthonic genera being forty-eight. There are 

 twenty-three pelagic species, and one hundred and nine- 

 teen benthonic species, of which nineteen are arenaceous 

 and one hundred are calcareous forms. 



A comparison of the pelagic species listed in the 

 table with the list of pelagic species given by Cushman 

 (1928) shows that eleven species noted as pelagic are not 

 present in the collection. Conversely, Globigerina con - 

 glomerata and rotundat a. Globorotalia hirsuta, and sev- 

 eral unnamed species are not listed in Cushman's book. 

 Globigerina conglomerata . G. inflata. and G. rotundata. 

 Globigerinoides conglobata and sacculif er a . Globigerinella 

 aequilateralis. Orbulina universa. Pulleniatina obliquilo - 



culata, Globorotalia menardii. G. truncatulinoides. and 

 G. tumida are all widely distributed pelagic species in 

 the Pacific, although the relative proportions of each 

 present in different samples vary considerably. Globig - 

 erina Sp. cf. G. buUoides, Globigerinoides rubra, and 

 n. sp(?), Globigerinella digitata, Candeina nitida, 

 Sphaeroidinella dehiscens, Globorotalia hirsuta. and 

 various unnamed species are not common in occurrence. 



The most common benthonic genera, in approximate 

 order of abundance, are Eponides. Pulvinulinella. Uvig - 

 erina. Cibicides. PuUenia. and Nonion . As with the 

 pelagic forms, the relative abundance of these genera is 

 quite variable in different samples. The genus Lagena. 

 of which over thirty species are identified, is widely 

 distributed. Other characteristic foraminifera of Pa- 

 cific deep-sea deposits are Dorothia bradyi, Pyrgo de - 

 pressa. Gyroidina soldanii. Cassidulina fava and C . 

 subglobosa. Ehrenbergina bradyi . and Laticarinina 

 pauperata . Arenaceous foraminifera are also charac- 

 teristic, particularly of deposits low in calcium carbon- 

 ate, but these are variable in appearance, usually frag- 

 mentary, and difficult to identify. 



It may be seen from an examination of tables 1 and 

 9 that in general the samples which have the highest 

 percentage amounts of benthonic foraminifera are usual- 

 ly, other things being equal, those of relatively lower 

 content of pelagic foraminifera (hence relatively lower 

 CaCOs content), higher proportions of broken shells, 

 and higher percentages of organic matter than other 

 samples of the same depth and general location. Cor- 

 respondingly, there is an inverse relation between the , 

 numbers of benthonic species in the samples and the 

 percentages of CaC03. This relation is shown in table 

 4 which gives, in addition to the depth and percentage of 

 CaC03, the numbers of benthonic species found in ten 

 samples in which all the observed benthonic foramini- 

 fera were carefully studied. 



Table 4. Relation between numbers of benthonic species 

 of foraminifera and the percentage of CaCOs 



Samples arranged in order of deer easing CaCOs content 



Sam- 

 ple 

 no. 



CaC03 



Depth 



in 

 meters 



No. benthonic species 



Arena- 

 ceous 



Calcar- 

 eous 



Total 



Samples 25 to 41 are from the southeast Pacific. It 

 may be seen from table 4 that the average number of 

 benthonic foraminifera in the samples from this region 

 which have more than 90 per cent calcium carbonate is 

 less than half the numbers present in samples of inter- 

 mediate carbonate content. Sample 31, a red clay having 

 only 20 per cent CaC03, contains the largest number of 

 benthonic foraminifera of any sample from this area. 

 Similarly, there is a great variation in samples 82 and 

 85 from the south central Pacific in the numbers of 



