600 p. G. CLAPP CLASSIFICATION OF PETROLEUM AND GAS FIELDS 



3. No porous stratum is consistent throughout^ but varies greatly in 

 its cementation, size, and arrangement of particles and therefore of pore 

 space. 



4. The common non-parallelism of different sets of strata in any field. 

 This is what we technically call the convergence of the strata. The struc- 

 ture of the productive stratum itself must be considered independently 

 of the configuration of structure in any surface formation. 



5. Dryness of certain sands. 



6. Extreme saturation of certain sands. 



Eelation between Structure and Topography 



A much closer relation exists in some fields between geological struc- 

 ture and topography than is commonly understood, but this coincidence 

 must be accepted with reservation. 



Arnold and Johnson state^^ that in the McKittrick- Sunset region of 

 California a very close relation exists between topography and structure, 

 the preservation of the forms being "due in part to the aridity of the 

 climate, which has prevented the obliteration of the main features, al- 

 though not always of the minor folds and in part to the recency of some 

 of the processes which have affected the folding and faulting." As ex- 

 amples are mentioned Pyramid Hills, Lost Hills, Elk Hills, Buena Yista 

 Hills, Antelope Plains, and Syncline Hill. The topographic effect of 

 faulting in that region is described as even more striking than that of 

 the folding, as exemplified by Palo Prieto Pass, the Elkhorn Scarp, 

 etcetera. 



A similar close topographic relation exists in places in Oklahoma and 

 Texas; in Wyoming it is very manifest, and it can be distinguished to 

 some extent in Pennsylvania, Mexico, Kansas, and Canada. 



Causes of Failui^e of geological Work in Search of Oil 



The common causes of failure are as follows : 



(1) Inadequate investigations, due to 



(a) Lack of funds allotted to the work. 

 (6) Lack of sufficient time. 



(c) Lack of engineering training on the part of the geologist. 



(d) Lack of geological training on the part of engineers. 



(e) Lack of distinction between "reconnaissances" and "de- 



tailed examinations." 



S0 Loc. cit., p. 93. 



