MARINE BOTTOM SAMPLES COLLECTED IN THE PACIFIC OCEAN 

 BY THE CARNEGIE ON ITS SEVENTH CRUISE 



INTRODUCTION 



The Carnegie, on its seventh cruise, collected 

 seventy-five samples of deep-sea deposits in the south- 

 eastern and the north Pacific. In 1930 these samples 

 were sent to Dr. T. Wayland Vaughan, Director of the 

 Scripps Institution of Oceanography, University of Cali- 

 fornia. He immediately arranged for the making of cer- 

 tain mechanical analyses by a member of the Institution's 

 staff, and he arranged with Dr. John A. Fleming of the 

 Department of Terrestrial Magnetism, Carnegie Institu- 

 tion of Washington, to have chemical analyses of forty- 

 five of the samples carried out by the Sharp-Schurtz 

 Company of Lancaster, Ohio. In the fall of 1931 Dr. 

 Vaughan offered the writer the opportunity of making an 

 extended study of the samples. It was expected that this 

 report would be completed at the end of about a year, 

 but the demands of other problems and the increasingly 

 widened scope of the study have combined to cause a de- 

 lay of several years in the completion of the work. 



Seiwell has a preliminary report on the samples 

 collected in the southeast Pacific, and Ault and Soule 

 (1929) have described the sounding methods used in that 

 area. Piggot (1933) has published a discussion of the 

 determinations of radium in many of the samples, and 

 Trask (1932) has determined and published in tabular 

 form the nitrogen content of nearly fifty of them. The 

 methods of collecting and storing the samples have been 

 described elsewhere in this volume. 



Scope and Nature of this Report 



This report contains an account of the general char- 

 acter of the deep-sea samples collected in the Pacific 

 by the Carnegie, and of the distribution of the various 

 deposit types, together with the results of chemical, me- 

 chanical. X-ray, and other types of analyses. As indi- 

 cated in the text, many of the analyses were carried out 

 in whole or in part by other investigators. 



Although the number of samples examined is rela- 

 tively small, they were collected from a large area, and 

 therefore afford an opportunity to re-examine many 

 problems of deep-sea sedimentation in the light of mod- 

 ern methods of sedimentational and soil analysis. The 

 questions which must be considered in such a study are 

 (1) the determination of the various constituents of the 

 samples with the view of ascertaining their physical and 

 chemical nature, origin, and history before and after 

 deposition; and (2) the classification of the samples from 

 the point of view of the causes of the variation in bottom 

 deposits with depth and location. In so far as these ques- 

 tions are answered, they may contribute to the solution 

 of such larger problems as the time rate of deposition in 

 the deep sea (see Twenhofel, 1929), the geologic history 

 of the ocean basins, and the nature of the changes which 

 the continental masses have undergone by reason of 

 their continuing contributions to the sea and the sea 

 floor. 



Only fragmentary and speculative answers to the 

 foregoing questions have resulted from the present 



study. Several modifications of the usual classification 

 of deep-sea deposits are suggested. An attempt has 

 been made to determine something of the nature and or- 

 igin of the fine materials which form a predominant part 

 of the noncalcareous parts of the samples. In addition, 

 the possible factors affecting the distribution of calcium 

 carbonate in the bottom deposits of the southeastern and 

 of the north Pacific are evaluated. 



Specific or generic identifications of many of the or- 

 ganic remains in certain representative samples were 

 made by various experts, but complete faunal lists for 

 all the samples are not given. Owing to the fact that 

 cores were not collected, except in one case, it has been 

 impossible to employ the method used so successfully 

 by Wolfgang Schott (1935) of estimating the rate of dep- 

 osition of deep-sea deposits from the vertical distribu- 

 tion of pelagic foraminifera. Similarly, although the 

 presence of abundant or significant mineral grains and 

 rock fragments of sufficient size to be identifiable by 

 ordinary optical methods has been recorded, complete 

 lists of such mineral and rock species in the samples 

 are not given. These relatively large grains are usually 

 minor constituents of deep-sea deposits and may be of 

 little significance in explaining the origin of the fine ma- 

 terials in the samples. Besides the seventy-five sam- 

 ples of Pacific deep-sea deposits, a few samples were 

 collected in the Atlantic and in shallow-water areas of 

 the Pacific. 



Acknowledgments 



The writer wishes to express his thanks to Dr. John 

 A. Fleming, Director of the Department of Terrestrial 

 Magnetism, Carnegie Institution of Washington, for the 

 privilege of examining the collection, for his generous 

 cooperation in the allocation of funds, and for the assist- 

 ance given by him and the staff of the Department in the 

 study of the samples and in the preparation of this re- 

 port. 



The author is greatly indebted to Dr. T. W. Vaughan 

 for the opportunity to make these studies, for his con- 

 stant aid in the preparation of the manuscript and in 

 enlisting the assistance of others, and for his encour- 

 agement. It is a pleasure also to acknowledge indebted- 

 ness to Mr. George Steiger, of the United States Geolog- 

 ical Survey, for making the spectrographic analyses; to 

 Dr. P. G. Nutting, of the United States Geological Survey, 

 for his report on the mean grain densities, weight hu- 

 midity, and weight temperature relations of certain of 

 the samples; to Professor W. P. Kelley, of the Univer- 

 sity of California, College of Agriculture, for determi- 

 nations of the base-exchange capacities and replaceable 

 bases of certain of the samples, and for advice with re- 

 spect to soil colloids; to Dr. Parker D. Trask, formerly 

 of the American Petroleum Institute and now of the Unit- 

 ed States Geological Survey, and Mr. Harald Hammar, 

 of the American Petroleum Institute, for determinations. 



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