70 Subsurface Geologic Methods 



16. In exploiting a new area for oil and gas, what major factors 



should the geologist consider? 



17. For what purposes are correlations of sedimentary rocks made? 



18. Give five basic procedures followed in correlating sedimentary 



rocks. 



19. Discuss briefly "magnitude of correlations." 



20. Give five difficulties commonly encountered in correlating data. 



