references, was reviewed by Hamilton (1974a, 1974b). Additionally, work had commenced 

 on studies of mean velocities and velocity gradients in the first, unhthified sediment layer 

 (Hamilton et al, 1974). 



During the three year program (1974-1977), NAVELEX, Code 320, has supported 

 partially the continued work in sediment properties and layer sound velocities and velocity 

 gradients and work concerned with the attenuation of shear waves and the relationship be- 

 tween sound velocity and density in the principal sediment and rock types of the sea floor. 



In the gradients of some important properties, NAVELEX has also partially sup- 

 ported shear waves in marine sediments versus depth in the sea floor, sound attenuation 

 versus depth in the sea floor, and density and porosity of sediments versus depth in the sea 

 floor. 



Additionally, geoacoustic models were furnished for a number of areas where 

 acoustic experimental work was planned or where predictions were required. 



The reports of these measurements and studies are included in our references under 

 Work Supported by NAVELEX, Code 320: 1974-1977. 



The work generally noted above will be summarized, with details and illustrations, 

 in the next sections. 



PROGRAMS IN GEOLOGY AND GEOPHYSICS 



SOUND VELOCITY AND RELATED PROPERTIES OF MARINE SEDIMENTS 

 (LABORATORY MEASUREMENTS) 



Introduction 



The geology-geophysics group operates a sediment laboratory in which measure- 

 ments are made of sound velocity, density, porosity, grain size and grain density of cored 

 sediments. During the past three years, funds have not permitted a field program. However, 

 through cooperative arrangements with Scripps Institution and others, the above measure- 

 ments have been made on various suites of sediments from the Pacific and Indian Oceans. 

 Specifically, there were sediments from six Scripps expeditions: four from the Central 

 Pacific and two from the Indian Ocean (Bay of Bengal and Andaman Sea). Additionally, 

 three suites of sediments from the Northeast Pacific were taken by Navy-sponsored groups. 



Measurements to July 1975 



The measurements of physical properties of sediments and their empirical relation- 

 ships (to about July 1975) have been studied and reviewed (Hamilton, 1975d). The data 

 were presented in three forms: as diagrams, in regression equations and in tables. 



One of the most useful and frequently used outputs of our work in physical proper- 

 ties of sediments is the production of a set of tables in which are listed the acoustic and 

 related properties of various sediment types in the three main environments of the sea floor. 

 The latest revision of the tables of sediment measurements (Hamilton, 1975d, 1976c) is 

 reproduced here as Tables la, lb, 2a and 2b. The earlier report (Hamilton, 1975d) also 



