f X 60 90' E 



£• t20°B0° W0°eifl20° W 



W 90 60 30 30 E 



f JO' 60'- 90' KO ISO' E 



Plate 2. Schemaiically simplified world-map of ocean dcpih. (.S<c : Vol I. Pi 1. p 1 3) 

 (The depth-iniervals are specified underncalh the map; the lellers and numbers are referred to in the text ; for Altantic Ocean »■*■ p 28. for Indian Ocean *(■<■ pp. i 



