LIST OF TABLES 



TABLE 



I. Dimensions of Sea, Land, and Earth 7 



II. Murray's Classification of Deep-sea Deposits 12 



III. Average Velocities of Types of Surface Waves 20 



IV. Velocities of a Surface-shear Wave along Different Paths 22 

 V. Dimensions of the Canyons off the Middle Atlantic States 122 



VI. Average Longitudinal Gradients of Submarine 



Canyons, by Groups 123 

 VII. Thickness of Silty Layer, Measured at Four Stations along 



the Length of Lake Mead (Feet) 146 



LIST OF FIGURES 



1. Map of the Mid- Atlantic Swell facing 8 



2. Diagrammatic Cross-section of a Continental Terrace 10 



3. Photograph of the Piggot "gun" facing 12 



4. Sliced Cores Brought Up from the Atlantic Floor facing 13 



5. Diagrammatic Seismogram, Showing Onset of Push, Shake, 



and Long Waves 14 



6. Seismogram for the Earthquake in Turkey in December, 1939 15 



7. Diagrammatic Cross-section of the Continental Part of the 



Earth's Crust 17 



8. Map of the Hawaiian Islands 19 



9. Map Showing Paths of Seismic Waves from a South Atlantic 



Center of Shock 22 



10. Map of the Seychelles Plateau 24 



1 1. Admiralty Chart of Ascension Island facing 24 



12. Diagrammatic Section Illustrating Departure of the Geoid from 



the Standard Spheroid under Two Circumstances 27 



