650 Tables 853-856 



OCEANOGRAPHY 



(See Nat. Res. Council Bull. 85, 1932.) 

 TABLE 853. — Area of Ocean Depths (Littlehales) 



Area of total water surface is about 365,500,000 km 2 . (Land surface about 153,500,000 

 km 2 .) 



Meters 0-200 200-1000 1000-2000 2000-3000 3000-4000 4000-5000 5000-0000 >6ooo 



km 2 x io« 30.60 16.40 18.05 36.45 7901 112.72 66.88 5.38 



% 8.4 4.4 4.9 9.9 21.7 30.8 18.4 1.5 



The continental shelf dips gradually (depth contour about 200 m) ; then a steeper con- 

 tinental slope (talus), the seat of many deposit slips, seismic disturbances. Insular shelves 

 and taluses, then troughs, trenches, basin deeps. 



TABLE 854. — Oceanic Gradients 

 Ocean bottom gradients, Atlantic Ocean between Equator and 47 N. latitude. 



Zone, N. lat 0-10 



Gradient 2o'.7 



Island gradients often great; St. Helena, up to 40°; St. Paul (Atlantic Ocean), 62 . 

 Gradients for volcanic and coral islands also great, generally in upper 300 m. Great 

 Caldera of Santorin > 50°. S. of Cuba, 76° W., to depth 2625 m, 35 30'. Compare 

 Fujiyama, Japan, fine volcanic peak, 35 ° ; 12 at base. Steep gradients (Alpine conditions) 

 westward of British, French, Iberian coasts (av. angle 13 to 14 ) and W. of continental 

 slope of California (San Diego to Point Conception) 14° between 2000 and 4000 m isobaths. 



TABLE 855. — Atlantic Ocean Basin. Areas and Depths (Littlehales) 



Depths, km 0-2 2-4 4-6 6-8 Over 8 Total area 



Areas, io" km 2 29.49 19.50 50.60 7.38 0.039 107.014900 



% of whole 27.6 18.2 47.3 6.9 0.4 100 



Remarkable feature : Mid- Atlantic Rise, of median course and continental extent, from 

 Iceland to S. polar border; throughout its more than 13 km, the general rise of its crest 

 is some 3 km above the basin bottom on each side. W. Atlantic trough 6 km deep over 

 large area of N. portion; other troughs and basins of similar depth. European isolated 

 depth of 6 km. Near Equator lessened depth, 1.9 km, and extension along Equator 34 to 

 15° W. long., cut by narrow gap 18 W., 4 to 5 km deep. Passage through gap leads 

 to Brazilian basin, 7.4 km deep. Ridge < 1 km deep leads from Greenland (Iceland is a 

 volcanic rise) to British Isles. 



Greatest depths: 54° 30' S., 28° 30' W., 8.050 km; 19 36' N., 66° 26' W., 8.351 km; 

 l 9° 35' N., 67 43' W., 8.525 km; 19 38' N., 68° 17' W., 8.198 km. See also page 651. 

 Greatest depth in Mediterranean, 4.400 km at 35 ° 45' N., 2i°46' E. ; Black Sea, entire 

 central basin below 2 km ; North Sea <C 200 m throughout. 



TABLE 856. — Indian Ocean Basin. Areas and Depths (Littlehales) 



Depths, km 0-2 2-4 4-6 Over 6 Total area 



Areas, io 9 km 2 8.192 18.569 44.569 4.656 75.986000 



% of whole 10.8 24.4 58.7 6.1 100 



Compared with Atlantic the bottom relief of the Indian Ocean is much simpler. 7 km 

 deep 250 km S. of Java 10° 1' S., 108 65' E. Persian Gulf, order of 0.09 km deep. Red Sea, 

 about 2 km. 



Smithsonian Tables 



