54 



(7) Can any inferences be drawn about the separation of North 

 America and South America (to provide space for the Caribbean 

 Sea) using the data to be obtained from the ocean floor between 

 Africa and the southern Mid-Atlantic Ridge? 



(8) Can we improve our mapping of the Atlantic Ocean in its stages 

 of formation in order to improve our concepts of changing ocean 

 currents and populations of marine organisms? 



(9) What is the origin of the prominent transverse ridges on the 

 ocean floor? 



The basic scientific results can be used (as they typically are used) 

 to denote areas where detailed surveys must be made in order to outline 

 new sedimentary basins. It would be surprising if the proposed cruise 

 fails to cross structures such as faults, folds, and diapiric intrusions, but 

 the traverses will be too far apart to outline these structures. 



The following are target dates: 



1. 1 January 1971 — start of program. 



2. 31 December 1971— 



a. completion of new shipboard systems: seismic profiling and 

 enhancement of records (new) ; seismic refraction, magnetics, 

 gravity, and data storage (old). 



b. publication of blue-cover report no. 1 on existing available 

 geophysical data in the region of interest. 



3. 20 January 1972 — begin first cruise. 



4. 30 June 1972 — begin data compilation beyond the shipboard proc- 

 essing. 



5. 30 December 1972 — publication of blue-cover report no. 2: ba- 

 thymetry, seismics, magnetics, and gravity of first cruise. 



6. 10 January 1973 — begin second cruise. 



7. 30 June 1973 — begin data compilation beyond the shipboard proc- 

 essing. 



8. 30 December 1973 — publication of blue-cover report no. 3: ba- 

 thymetry, seismics, magnetics, and gravity of second cruise. 



9. 1 January 1974 — begin a full year of data analysis, model studies, 

 and publication of results. 



10. 30 December 1974 — end of project. 



NASCA LITHOSPHERIC PLATE STUDY 



Despite the widespread acceptance of the new global tectonics in 

 the earth sciences, there is only limited knowledge regarding the mech- 

 anisms of sea-floor spreading and of continental drift in the complete 

 tectonic cycle of oceanic rift-plate-trench systems. In recent years our 

 understanding of the processes taking place at the diverging edges (the 

 oceanic rift zones of sea-floor spreading) has increased. But we have 

 little understanding of subsequent geophysical and geological events during 

 transport of the lithospheric plate and of the processes and events occur- 

 ring in zones of convergence where an oceanic plate is subducted under 

 a continental boundary and the crustal material, originally created at the 

 midocean rift, is finally lost. 



