22 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1921. 



erals, if thev can be found, alToid a miu-h sim- 

 pler, more direct , and moi'e rapid means of i-ecog- 

 nizing horizons than the method here presented 

 they are worth looking for. 



Except as a means of locating producing 

 beds, however, correlation is for the petroleum 

 geologist merely a preliminary to the solution 

 of his other prol)lems, such as paleogeography, 

 accumulation and migration of oil, and m(^ta- 

 morphism — or, as some may prefer to call it, 

 diagenesis and metamorplii^m — of the rocks 

 as an index to tiie processes tiiat have affected 

 the oil. The solution of these problems 'will 

 be advanced not, I believe, by direct obsei-va- 

 tion in a single well but by com])ilation of simi- 

 lar (lata from a great number of wells, in the 

 same way that the j)roblems of surface geology 

 are solved by ureal mapping. The acquisition 

 of the necessary data is beyond the ca])acity 

 of a single individual or a single organization. 

 It is therefore to be hoped that tlie pi-oducers 

 of oil will sufliciently realize the importance to 

 their industry of the solution of these jii'obk^ms 

 to (enable th(ur geologists to cooperate in inves- 

 tigating them. 



Geologists in general should come to regard 

 the studv of well drillings as a field worthy of 

 special attention. The information afforded 

 l)y a continuous secjuence of drillings fi-om a 

 single well, from the wells in an extensive fiekl, 

 and from several fields in a larger area has a 

 detail, completeness, and extension vdiich are 

 generally lacking in surface observations. 

 Moreover, once a field is fully drilled an oppor- 

 tunity to acquire records of its subsurface 

 stratigraphy is gone forever. It is ther(>fore to 



be ho|)eil that every effort will be made to pre- 

 .serve complete series of samples from wells 

 and that central places may be found where 

 thest* samples can be stored for permanent 

 reference, 



ACKNOWLEDGMENTS. 



Both series of well samjjles examined for this 

 report were obtained from the lloxana Petro- 

 leum Cori)oration of Texas. The ol)ligation of 

 the United States Geological Survey to this 

 organization for the progressive and enlight- 

 ened spirit and the readiness to cooperate 

 which made these materials available is so ob- 

 vious that it need only be mentioned. The 

 wTiter wishes, m addition, to ex])ress his special 

 indebtedness to Mr. E, Ci. Allen, of that corpo- 

 ration, for his kindness and ])rom])t readiness 

 in helping with information and additional 

 material on many occasions, 



Tli(^ obligation of the Geological Sm-vey to all 

 those organizations and individuals who have 

 furnished samples which for one reason or an- 

 other hap]K>n not to have be(Mi used hi this hi- 

 vestigation is none the less cordially acknowl- 

 edged. 



Personally, I wish to acknowledge my s]>ecial 

 o])ligation to Mr. David White, chief geologist 

 of the Geological Survey, whose faith hi the pos- 

 sibiliti(>s of this investigation led to its mitia- 

 tion and whose encouragement has helped its 

 ]U'ogress, I am also hidcbted to Mr. K. C. 

 Heald, assistant chief of the section of the 

 geology of oil and gas fields of the Geological 

 Survey, for procuring samples and hi other 

 ways supporting the work. 



