Deep-sea Exploration

that branch of thala ography which investigates the depths of oceans, seas or lakes, determines the nature and Gis tri but i on of the organic life there to be found, the temperature, constitution and specific gravity of the water at varying distances from the surface, the causes and.characteristics of ocean currents, the geological changes in the way of gradual or = upheaval or subsidence caused by volcanic action and the formation of atolls and other islands.