John D. Todd is a native of Beaumont, 

 Texas. He received degrees, including the 

 Ph.D., in geology and law from the Univer- 

 sity of Michigan. He has been a geologist and 

 petroleum producer on the Gulf Coast for the 

 past 25 years. He is the President-Owner of 

 Cambe Log Library. He is the author of 

 15 magazine articles and is chairman of 

 the Valuation Study Group of the Houston 

 Geological Society. He is a member of the 

 American Association of Petroleum Geologists, 

 the American Institute of Mining & Metallur- 

 gical Engineers, the Texas Bar Association, 

 and the Texas Registered Professional Engi- 

 neers. 



Russell B. Travis, a native of California, re- 

 ceived a degree in geological engineering 

 from the Colorado School of Mines in 1943, 

 and a Ph.D. degree in geology from the Uni- 

 versity of California in 1951. He served as 

 an officer in the U. S. Navy from 1943 to 

 1946. He was a geologist with the Standard 

 Oil Company of California from 1946 to 

 1947 and Assistant Professor of Petrography 

 at the University of Idaho in 1951. He was 

 employed as a geologist with the International 

 Petroleum Company, Ltd., Talara, Peru, from 

 1951 to 1953. He became Assistant Pro- 

 fessor of Geology at the Colorado School of 

 Mines in 1953 and in 1956 returned to Talara, 

 Peru, with International. He is a member of the American Association of 

 Petroleum Geologists, the Geological Society of America, the Mineralogical 

 Society of America, and Sigma Xi. He is the author of Classification of Rocks, 

 published as a Quarterly of the Colorado School of Mines. 



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