THE OKLAHOMA FIELDS 000 



at shallow depths, has recenth- been shown to contain gas on a dome at 

 Garber and at shallow depths on an anticlinal structure at Billings, 

 However, the nature of the Permian over a great part of its area in Okla- 

 homa is adverse to its proving an oil-bearing series of much note. As a 

 rule, its strata are subaerial in origin and were thoroughly oxidized and 

 leached of oil-bearing materials at the time of deposition. The Permian 

 in Oklahoma is ordinarily referJ^ed to as the "Eed Beds/' owing to the 

 prevailing color of the sandstone and shale beds that compose it. Btit 

 northward into Kansas the lower portion of the series changes its nature 

 and is composed of beds of blue, black, and gray shale, thin beds of lime- 

 stone and gray sandstone. The fact that gas is found in Permian sands 

 on certain structures in Oklahoma and Kansas suggests the possibility 

 that these sands may carry oil locally in some districts of this general 

 region. 



Throughout much of the Permian area the upper members of the 

 Pennsylvanian series lie just beneath the base thereof and offer splendid 

 chances of furnishing new oil fields. In fact, the well of the Sinclair Oil 

 and Gas Company on the Garber dome has recently encountered a sand 

 in the top of tlie Pennsylvanian at 1,100 feet, which for some weeks 

 (December, 1916) has been flowing at the rate of 60 to 100 barrels per 

 day. This is an entirely new oil-producing horizon in Oklahoma, and is 

 certainly a very important discovery in looking forward to the future oil 

 ])ossibilities of the territory farther west in that State and Kansas. 



Heretofore it has been the custom for operators in the Pennsylvanian 

 area of Oklahoma to stop drilling at the top of the Mississippian lime- 

 stone; but the time is at hand when test wells on good structure should 

 be drilled down into and through the Mississippian for possible oil sands 

 at deeper levels (see the general sections presented herewith). Very few 

 test wells, even in the shallow area, have been drilled to a sufficient depth 

 to encounter the Sylamore sandstone of the Devonian or the Burgen^ 

 sandstone of the Ordovician systems. The writer has observed residue 

 oil in considerable quantities in the Sylamore sandstone in Cherokee 

 County, Oklahoma, whete it outcrops east of the oil fields. 



STRUCTURE 



structural features that accompany the concentration of oil ajid gas 

 Ml Oklahoma are of two types: the regional and the local. The oil fields 

 Me within certain general areas, due to tlie position of those areas with 

 respect to surrounding mountains, but actual concentration is confined 

 to irregular folding of the strata in local districts. Approaching the 

 Ouachita Mountains from the north the Pennsylvanian series passes into 



LII — Bull. Geol. Soc. Am,. Vol. 28. 1916 



