ILLUSTRATIONS (Continued) 



29 Sutured animal mounds, in churned red clay, intermountain 



valley of Rift Mountains, Indian Ocean. . .48 



30 Worm and excrement on mottled clay near Cocos Keeling 



Island, Indian Ocean. . . 4 9 



31 Starfish, brittle star, and sea pen in churned silty clay, 



west slope of Guaymas Basin, Gulf of California. . . 4 9 



32 World maps showing NEL sea floor camera stations and 



underwater topographic features: 



A. Zones of isoroughness. . .57 



B. Roughness due to ripples and bedrock. . . 58 



C. Roughness due to manganese nodules . . .59 



D. Roughness due to benthonic organisms . . . 60 



E. Roughness due to biological churning of sediment . . . 61 



