698 



J. H. GARDNER THE MID-CONTINENT OIL FIELDS 



occurs ill a very limited portion of the basal section and in a district 

 southeast of the oil fields. The McAlester-Coalgate region, which con- 

 tains the coal beds, extends over a small percentage of the Penns3dvanian 

 outcrop. Wells drilled for oil and gas in the oil-bearing region have 

 penetrated all portions of the Penns3dvanian series from the uppermost 

 member down to the Mississippian limestone, but seldom do the logs 

 show any coal whatever. In the vicinity of Tulsa and northward the 

 Dawson coal bed is worked in a small way by stripping and shallow drifts ; 

 it is a bed of slight thickness and limited extent, although interesting, in 



Figure 4. — Structure Contour Map in eastern Osage County, Oklahoma, sJiotcing 

 crumpled Nature of the Folding, based on Well Logs to Bartlesville Sand 



From map by F. Julius Fobs 



that it occurs abnormally high in the series. There is also a local occur- 

 rence of coal near Foraker, in Osage County, which lies at a still higher 

 stratigraphic level. 



Certain beds of sandstone in the Pennsylvanian section, or sandy, frac- 

 tured limestone, such as the Wheeler, constitute the so-called "oil sands." 

 Sandstones in the Mississippian series and the Cretaceous system have 

 furnished oil and gas to a limited extent, but less than one per cent of 

 the oil produced in the State comes from these strata. The Permian 

 series, which contains a notable amomit of gas on the Blackwell anticline 



