SECT. 2] 



ABYSSAL PLAINS 



32U 



Mediterranean one would offhand expect to find a large abyssal plain lying sea- 

 ward of the Nile. However, such a feature is not found. Although the region 

 seaward of the Nile has been smoothed by sediments derived from the Nile 

 delta, the smoothing has not proceeded to such a point that an abyssal plain 

 has formed. An extremely small abyssal plain is found to the south of the 

 Straits of Messina and is probably fed by material coming from the straits, 

 judging from the events associated with the 1908 Messina earthquake (Heezen, 

 1957). It seems probable that many of the small basins making up the Aegean 

 Sea have flat floors. However, little of this area has been investigated with 

 precision sounders. 



DISTANCE IN NAUTICAL MILES 



Fig. 12. Nine topographic profiles across the Gulf of Mexico. (After Ewing, Ericson and 

 Heezen, 1958.) 



The Gulf of Corinth, a small slit of ocean separating the Peloponnisos from 

 the mainland of Greece, is floored by a small abyssal plain 1-2 mi wide and 

 10-12 mi long. 



Judging from the distribution of sediments in the floor of the Black Sea, 

 one would predict a fairly extensive plain. However, no detailed sounding is 

 available for this area. Zenkovich (1958) has reported numerous abrupt changes 

 in depth off the mouths of various rivers of the eastern Black Sea coast. Tur- 

 bidity currents generated in this area would be expected to supply sufficient 

 sediments to produce an abyssal plain seaward of the Caucasus. 



b. Gulf of Mexico 



The Sigsbee Abyssal Plain lies in the center of the Gulf of Mexico at the foot 

 of the Mississippi Cone (Figs. 11 and 12). It is virtually level in the central part 

 12— s. Ill 



