Assuming velocity (V) a function of depth (Z), geologic time (T), and lithology (L) the resistivity log is an approach to the determination of L. Since general knowledge of water resistivity values (R w ) is lacking, the values of true resistivity (R t ) against V/alpha (ZT) 1 6/ were compared for 670,000 feet of section widely distributed geographically. Variations in R w were presumably averaged out thereby, and the results indicate that statistically L = [R t ]/T and V = 1948 (ZTL) 1 6/. This formula was applied to an additional 270,000 feet of section more localized geographically to observe its accuracy in predicting vertical travel time. If a correction map for R w variations is applied the results are encouraging but less accurate than good velocity surveys.Examination of an inconclusively small amount of data with more careful measurements of R t suggests that accuracy comparable to direct measurement may be attainable. The cooperation of other investigators and of the electric-logging specialists is desired.

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