The Ocean 



15 



Table 2. Frequency and areas of individual height- and depth-intervals of the earth crust 



(According to Kossinna, 1921) 



Interval 

 (m) 



Areas 

 (10« km-) 



Per cent 



Interval 

 (m) 



Areas 

 (10' km^) 



Per cent 



The position of the two maxima can be fixed more closely by investigation of denser 

 intervals. It is apparent that one maximum falls within the interval 0-200 m and the 

 other within the depth interval 4600-4800 m. The structure of the crust thus in- 

 cludes two special areas: (1) a land area with a height of 100 m to 200 m, and (2) a 

 sea area at a depth of about 4700 m. These two areas together include almost 65% 

 of the entire surface of the Earth. These relationships can also be shown in another 

 way in the "Hypsographic curve for the surface of the Earth" (Fig. 9) which depends 

 on the areas in each separate height- and depth-interval over the surface of the Earth. 



10 

 8 

 6 



4 

 I 2 



i 



Q 

 -2 



-4 



-6 



-8 

 -10 



Average level of the physicol earth surface J +_245m 



Continental block 



I I I I I I I I I 



^Continental slope I 



■ 1270m I I 



Average crust level".- 2.440 m 



I M I I I I I I 



Average ocean depth:— 3800 m 



100 



400 



200 300 



mill, qkm 



Fig. 9. Hypsographic cur\e for the surface of the Earth. 



