RELATIONS OF THE OILS TO STRUCTURE 



64S 



certain conditions in joints, 

 etcetera, o f metamorphic 

 rocks where overlain by oil- 

 bearing sediments. 



The greater number of 

 the reservoir forms listed 

 are . too well known to re- 

 quire further explanation. 

 Among the irregular lenses 

 of depositional origin i s 

 mentioned "originally 

 warped" beds. These are 

 beds which, like the lower 

 gas-bearing layers of the 

 Potsdam, were deposited as 

 somewhat uniform mantles 

 over underlying unconform- 

 able surfaces and possess 

 original curvatures similar 

 to those elsewhere formed by 

 folding. Fossil bars, spits, 

 and allied deposits are more 

 frequent than is usually 

 imagined. Current deposits 

 filling channels in older or 

 in contemporaneous beds 

 are by no means uncommon. 

 They are almost invariably 

 coarser than the surround- 

 ing material, even conglom- 

 eratic. 



CONFINING AGENCIES 



These are likewise of 

 -great importance, since fa- 

 vorable structures and ade- 

 quate reservoirs will be un- 

 availing in the absence of 

 agents capable of effecting 

 the retention of the oil. The 



-W.Vik. Line 



