394 



HKKZKN AM> K\\ INf! 



[CHAl-. It) 



The mid-oceanic ridge in the equatorial Atlantic in general is characterized 

 by greater relief and has a more rugged and youthful appearance than in either 

 the North Atlantic or South Atlantic. In the equatorial Atlantic the ridge is 

 offset westward over 2000 miles by a series of left slip faults (Fig. 4). It is 

 probable that fracture zones will be found when the South Atlantic is better 

 surveyed. 



Seamounts and seamount groups, which are found in all provinces of the 

 oceans, are widely scattered throughout the Mid-Atlantic Ridge. Sometimes 

 the seamounts are distributed in a random pattern but more often they occur 

 along linear rows suggesting an association with fracture zones. 



TANGANYIKA (pT MALDiNI) 

 



3000 



RIFT VALLEY 



ZANZIBAR 







3000 



3000 



5 00 

 NAUTICAL MILES 



IQOQ 



VERTICAL EXAGGERATION 57 I 

 AFTER FARQUHARSON (1936) 



PROFILES ACROSS RiFT BELT 

 INDIAN OCEAN 



2000 



O MAJ.DIVES 



(KARDIVIA CHANNEL) 



m 



-15 



-0 



Fig. 6. Rift valley profiles, Indian Ocean. (After Farquharson, 1936. Soundings made by 

 M.S. Mahahis during the John Murray Expedition.) 



4. Indian Ocean 



In the Indian Ocean there is a clearly delineated belt of epicenters which 

 continues uninterrupted from the South Atlantic (Rothe, 1954) to the vicinity 

 of Rodriguez Island, at which point the belt sphts, one branch continuing 

 towards Macquarie Island, the other entering the Gulf of Aden where the mid- 

 oceanic ridge epicenter belt joins with the seismic belt associated with the East 

 African rift valleys (Fig. 5). Sounding profiles reveal a median ridge which 

 coincides with the epicenter belt. Soundings by Mahahis (Farquharson, 1936) 

 reveal that the section of Mid-Indian Ocean Ridge from Rodriguez Island to 

 the Gulf of Aden (known as the Carlsberg Ridge) is longitudinally split by a 

 prominent central valley. 



Recent cruises of Vema in previously unsounded areas have found a con- 



