Ch. 4] ENGINEERING GEOPHYSICS 87 



come evident. It is unlikely that any member of that group will ever 

 become a victim of similar circumstances again. 



PROBLEMS SUGGESTED FOR FUTURE RESEARCH AND 

 DEVELOPMENT 



Engineering Geophysics 



The examples outlined above in this field are largely confined to 

 problems of the ground, ranging in depth from the surface of the earth 

 to a few hundred feet. In terms of the accuracy and resolving power 

 of geophysical methods applied to exploration, many of these near- 

 surface problems offer great promise of valuable solutions. Sedimen- 

 tologists confronted with these problems should be readily able to de- 

 velop methods of attack when equipped with a good working knowl- 

 edge of applied geophysics. The barrier to rapid progress in this field 

 of development seems to lie in the transfer of knowledge and under- 

 standing from existing areas of application to those requiring geo- 

 physical aids for the first time. It is obviously impossible to im- 

 part in a short time the full scope and limitations of geophysical 

 methods to problems of applied sedimentation. The outlook is not 

 hopeless, however, and it is believed that, equipped with a general out- 

 line, the student of applied sedimentation may select from the litera- 

 ture the educational material he needs for his tasks. From a brief 

 reading of the material of interest in the list of references at the end 

 of this chapter, the geologist interested in sedimentation should quickly 

 place himself in position to discuss the problems in further detail with 

 expert geophysicists. By these means it is believed that an adequate 

 dissemination of geophysical knowledge may be accomplished. 



Seismograph. The principal function of this instrument is to meas- 

 ure depths to key horizons of sediments and rocks. A derived func- 

 tion is to identify such horizons, enabling one to establish correlations 

 of stratigraphic or lithologic equivalents over their lateral extent. 

 It may also show the presence of discontinuities and transitions in 

 sediments and rocks. From seismic data it is possible to infer the dis- 

 tribution of sedimentary and rock formations, their dimension, shape, 

 attitude, and identity. Often it is possible to infer something of the 

 detailed nature of a formation such as, for example, the distinction 

 between rocks which are massive and those which are composed of a 

 series of stratified layers. 



The gravity meter. This instrument may be adapted to near-surface 

 problems in the detection of deposits of sediments, rocks, and minerals 



