36 



INTERNATIONAL ASPECTS OF OCEANOGRAPHY 



tains information on material on the bottom of the 

 Indian Ocean. Basaltic lava, dredged at two places, 

 is noteworthy because of its low radium-content. 



The relative exploration of the sea-bottom for 

 material composing it is only approximately indi- 

 cated by the distribution of stations for serial sec- 

 tions of temperature and salinity, for numerous 

 bottom samples have been collected at places for 

 which information on the physical features of the 

 water is lacking or inaccurate. There are large 

 areas in the Pacific and Indian Oceans, the same 

 areas for which other information is deficient, from 

 which few or no collections of bottom material have 

 been made. 



During recent years there have been great changes 

 in the methods of studying marine sediments due to 

 the application of the principles of physical chemis- 

 try to numerous problems of the .sediments them- 

 selves and to problems of the seawater associated 

 with the sediments and due to the utilization of 

 X-ray analysis. It is not necessary to discuss the 

 methods of this later work for they are described 

 in connection with the reports on the samples col- 

 lected by the Meteor, Carnegie, and other re- 

 search vessels, and in other papers on marine 

 sediments. It is pertinent to call attention here to a 

 volume "Symposium on Recent Sediments" now 

 in preparation by the Committee on Sedimentation 

 of the United States National Research Council, 

 under the editorship of Parker D. Trask. Many 

 specialists are cooperating in the work. 



Another development of significance is the im- 

 provement of the older, and the invention of new 

 devices for obtaining cores of the sea bottom. 

 There have been numerous modifications of Ekman's 

 bottom sampler, which depends upon a weight to 

 drive a tube into the bottom. One helpful modifi- 

 cation is that of Trask.' A comm.endable feature of 

 Trask's design is its cheapness, the cost need not 

 exceed about five dollars. Another valuable device 

 is that of Kuenen.' 



The most noteworthy advance in the design of 

 coring devices is that of Piggot.'" The power to 



* Trask, Parker D., Oceanography and oil deposits: 

 Amer. Geophys. Union, Trans., Nat. Res. Council Bull, 

 no. 61, pp. 235-242, 1927. 



Trask, Parker D., Origin and environment of source 

 sediments of petroleum: Gulf Pub. Co., Houston, Tex., 

 1932. See p. 12, fig. 1, C. 



' Kuenen, Ph. H., Die Viermeter-Lotrohre der Snellius 

 Expedition: Ann. d. Hydrogr. u. marit. Meteorologie, 

 March, 1932. 



'" Piggot, C. S., Apparatus to secure core samples from 

 the ocean bottom: Geol. Soc. Amer. Bull., vol. 47, pp. 675- 

 684, 3 pis., 1 fig., 1936. 



drive the tube into the bottom is derived from an 

 explosive, that is the upper part of the apparatus 

 is a gun. The numerous cores, up to ten feet 

 long that have been taken, retain the stratification 

 of the material sampled and make possible a study 

 of the stratigraphy of the bottom material. It 

 may be confidently expected that the Piggot gun 

 will come into general use for sampling sea-bottom 

 material, and that those samplers that take material 

 only from the surface of the bottom will be replaced. 

 Provisions for operating the Piggot gun have been 

 made on the research vessels of both the Woods 

 Hole Oceanographic Institution and the Scripps 

 Institution of Oceanography. It is probable that 

 similar arrangements will be made on other vessels. 



The incentive that led Doctor Piggot to invent 

 his gun was to procure core-samples for the study 

 of the radium-content of marine bottom-deposits. 

 He determined the amounts of radium in a series of 

 samples collected by the Carnegie by means of a 

 snapper-type of sampler. The results were not 

 altogether satisfying — cores were needed. He has 

 kindly prepared the following summary statement 

 for this report. 



Radium Content of Marine Bottom Deposits, by 

 C. S. Piggot, Geophysical Laboratory, Carnegie 

 Institution of Washington. 



Though many determinations have been made 

 of the radium content of various rocks from many 

 localities on the continental surfaces of the earth, 

 very few .such measurements have been made on the 

 materials comprising the ocean-bottom sediments. 

 The reasons for this are obvious, but when the vast 

 area covered by these sediments is considered, and 

 especially their high radium content, it is apparent 

 that they may have a geophysical significance of 

 very great importance. 



The meagerness of the available data is empha- 

 sized Vvhen it is pointed out that only some sixty- 

 eight determinations have been published, of which 

 Joly published twelve in 1908, '^ Hans Pettersson 

 twenty-eight in 1930,'- and Piggot twenty-eight in 

 1932", and these represent a material covering nearly 

 three-fourths of the surface of the earth. Further- 

 more, these sediments are of unknown thickness, and 

 as there is little likelihood that direct measurements 

 of the thickness will ever be made, a knowledge of 



" Joly, J., Phil. Mag., vol. 16, p. 190, 1908. 



'- Pettersson, Hans, Teneur en radium des depots de mer 

 profonde: Resultats de Campagnes Scientifiques par Albert 

 I<" Prince Souverain de Monaco, fascicule 81, 1930. 



" Piggot, C. S., Radium content of ocean-bottom sedi- 

 ments: Amer. Jour, of Sci., vol. 25, pp. 229-238, March, 1933. 



