THE STRUCTURAL CLASSIFICATION 



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majority of oil fields of the world, and as a matter of fact is common 

 in the Appalachian, Ohio, Indiana, Illinois, Mid- Continent, Wyoming, 

 northern Louisiana, and some of the California fields in this country, 

 and supposedly in the Eiissian, Austrian, Burma, and Borneo fields in 

 the eastern hemisphere. Class II is divided into five subclasses, in order 

 to distinguish between various structural relations in which oil ig found 

 associated with anticlines and synclines. 



Figure 1. — Examine of siihacUnal Structure (Class I) in Stephens County, OJclahoma 

 Scale : 1 inch =r 1.45 mile ; contour interval, 20 feet 



The best known examples of the distinctions in Classes II and III 

 come from Ohio, West Virginia, and Pennsylvania, where some of the 

 largest oil and gas fields exist.. A generalized cross-section of these fields 

 from west to east is shown in figure 2. In this section the pools of Sub- 

 class 11(c) are situated on the crest of theCincinnati geanticline in north- 

 western Ohio and northeastern Indiana, the oil and gas being contained 



