features. It is now known that the rift valley at this longitude is 1 to 2 

 kilometers wide bounded by a steep scarp to the west with a median 

 feature of alternate elongated 100-meter high hills and similarly 

 proportioned troughs. The French have observed that rocks from 

 these central highs pop and break when brought to the surface and 

 that the near bottom magnetic anomaly over the median features is 

 especially large even for the axial valley. Although it is difficult to 

 identify tectonic features on the rift valley floor, scarps of small 

 dimensions are found there with trends parallel to the axial structure 

 and general trend of the median valley. 



Preliminary results have already revealed regions of anomalous 

 seismic activity, heat flow, rock types, and morphological 

 characteristics. The followup analysis of geophysical information 

 and rock samples will serve to relate the magnetic and petrologic 

 properties of rock samples obtained by the submersibles with the 

 magnetic and bathymetric profiles and to relate the seismicity and 

 heat flow results to the tectonic structure inferred from the magnetic 

 anomaly and bathymetric observations. The comparison of the 

 various mapping, sampling, and photographic techniques will be one 

 of the important results of this project. 



Progress has been made in a special training program for 

 submersible pilots and diving scientists. The submersibles have 

 been outfitted with special instruments, including rock chippers and 

 drills, transponder navigation system, video tape recorders, and 

 data loggers. The Alvin, owned by the U.S. Navy and operated by the 

 Woods Hole Oceanographic Institution, has been refitted with a 

 titanium hull to permit it to dive to 12,000 feet. While the Alvin 

 undergoes final refitting and testing, the American scientific diving 

 team is gaining experience with the Aivin during dives in shallower 

 water. The French have completed training dives in Archimede in the 

 Mediterranean and seven preliminary dives in the FAMOUS area. 

 The French and U.S. diving scientists have made a field trip to 

 Iceland and Hawaii respectively, where rock forms were studied. 

 Tests are being made of the new French submersible Cyana 

 (SP3000], which will be used in 1974. Although the number of dives 

 made by the French submersible Archimede in the summer of 1973 is 

 insufficient to map the area covered, the dives have produced 

 considerable data confirming bathymetric interpretations and have 

 provided excellent detailed photographic coverage for analysis and 

 interpretation. 



Plans are being formulated for some 40 dives by the three 

 submersibles in 1974. Aivin will begin work in an area adjacent to 

 the French dive area in 1973, covering a central graben and a second 

 medial high. This primary dive area will extend up the west wall 

 onto a bench above the 1300-fathom contour. The secondary 



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