Ch. 35] CHARTS AND MANUALS 661 



measure the sound-transmitting and -absorbing qualities of various 

 types of sediments in the laboratory, but these initial tests were gen- 

 erally unsatisfactory, and this portion of the field is still largely un- 

 explored. 



Some flume and model experiments, together with field measure- 

 ments, have been made to determine the relative importance of factors 

 that affect the stability of ground mines and of bottom-mounted equip- 

 ment, but this field also lacks detailed quantitative data. More was 

 accomplished during the war on the effects of waves, currents, sub- 

 marine topography, and beach characteristics on landing operations, 

 and work is continuing in connection with general studies of wave and 

 beach phenomena. Much remains to be done, especially on the factors 

 affecting the trafficability of beaches. 



Surveys 



Detailed surveys of the ocean floor, in which improved sampling de- 

 vices and photographs of the bottom were used, have been made in 

 connection with acoustic research and the installation of special elec- 

 tronic equipment on the bottom. The results of some of this work have 

 been published (Emery, 1948a; Shepard, 1948), and more is in process 

 of publication. Reconnaissance surveys, and data obtained by labora- 

 tory ships and by naval vessels on training operations such as "High- 

 jump" (the Navy expedition to the Antarctic in 1946-47) , are vastly 

 increasing our knowledge of the sediments and topography of the ocean 

 basins (Hess, 1948; Dietz, in press). It is estimated that several hun- 

 dred cores and bottom photographs and several thousand surficial 

 samples were taken by Navy activities and private research institu- 

 tions with Navy contracts during 1949. 



Charts and Manuals 



One of the projects that engaged a number of geologists during 

 World War II, including the writer and the editor of this symposium, 

 was the compilation of all existing oceanographic information in areas 

 of strategic importance, and the preparation of charts, texts, and man- 

 uals to enable naval operating forces to use this information effec- 

 tively. Forty-three "Bottom Sediment Charts" were prepared by the 

 UCDWR for areas along the Asiatic coast and Dutch East Indies; 

 twenty-five of these were published by the Hydrographic Office (Shep- 

 ard, Emery, and Gould, 1949) . Others, made at Woods Hole Oceano- 

 graphic Institution, covered parts of the Atlantic coast of the United 

 States and small parts of the west coasts of Europe and Africa. "Sub- 

 marine Supplements to the Sailing Directions," essentially climatic 



