Figure 26-14. Portion of variable-density profile approaching flank of shallow salt dome. The 

 steep dip arises from the near-vertical salt contact lying to the left of the section shown. 

 (After Palmer, 1957) 



The development of new techniques and instrumtentation is continually 

 under way in the laboratories of oil companies, seismic contractors, and seismic 

 instrument makers. The continuous velocity logger, the magnetic recording 

 systems, and directional energy sources (multiple vertically disposed shots) are 

 typical examples of fruition of this effort. Perhaps one of the most novel of 

 recent developments is the "Marine Sonoprobe" (Dobrin and Dunlap, 1957). 

 In essence a fathometer, this device displays on a continuous section the layering 

 within the first few hundred feet of the sea bottom. Figure 26-15 shows a 

 typical Sonoprobe profile. 



As in all fields of technology, basic research in geophysics is responsible 

 for its progress. Just as Mallet, Knott, Fessenden, Mintrop, Haseman and 

 Karcher, and their scientific contemporaries and successors suggested and de- 

 veloped the seismic method, their counterparts of today may generate a new 

 way of exploring for oil. But until they do, the seismograph will remain a 

 dominant exploration tool. 



The authors express their gratitude to E. J. Stulken and Ben Giles for 

 their review and criticism of this chapter. 



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