8 PRINCIPLES OF STRATIGRAPHY 



edge of the continental shelf, i. e., between — 200 and — 2,400 

 meters depth. 2. The continental platform (Kontincntaltafel) , be- 

 tween — 200 meters below and -f~i'000 meters above sea-level; 

 and 3. The culminating land region (Kulminationsgehiet) from 

 1,000 meters to 8,840 meters above sea-level. The abysmal regions 

 are divided into (a) the deep sea platform (Tiefseetafel), between 

 the median sphere level ( — 2,400 meters) and — 5,000 meters 

 depth ; and (b ) the depressed region (Depressionsgebiet) , below 



Meter 



Million square kilometers. 

 Fig. I. Hypsographic curve, showing subdivisions of the heights of the land 

 and of the depths of the sea. (After Kriimmel.) 



— 5,000 meters. A more satisfactory dividing line is placed by 

 Kriimmel at 5,500 meters. (Fig. i.) The continental block has 

 roughly the form of a star surrounding the north pole, and ex- 

 tending its rays southward. (Penck-22:/i'7.) Two principal 

 divisions of these rays are recognizable, the Old World and the 

 New World, of which the first is divided into three continents, 

 Eurasia, Africa, and Australia, and the other into two : North 

 America and South x^merica. The divisions are brought about by 

 deep indentations from the sea, constituting the mediterraneans. 

 Besides the five continents mentioned, there is the continent of 

 Antarctica, still little known, but larger than Australia in area. 

 The two main divisions of the continental block are separated by 

 the "arctic mediterranean." 



