BULLETIN OF The geological society of AMfct^ICA 

 Vol. 28, pp. 655-666 SEPTEMBER 30, 1917 



OIL FIELDS OF ILLINOIS ^ 



BY FRED H. KAY 



{Presented before the Society Decemher 2S, 1910) 



CONTENTS 



Page 



Introduction ; 655 



Stratigraphy 657 



Structure 657 



General structure of State , 657 



Periods of diastropMsm 658 



Relation of fields to structure 659 



Conditions affecting accumulation 659 



The La Salle anticline 659 



Isolated pools on east-side anticline 660 



Mode of origin of sands 661 



Heavy oil in Flat Rock pool 663 



The Colmar field of western Illinois 664 



Content of oil per acre 666 



Il^TEODUCTION 



After the discovery of the Illinois oil fields in 1905 it was but three 

 years until the State had reached its maximum production of 33^686^238 

 barrels. From that amount a somewhat irregular decline has occurred, 

 and in 1915 only 19,041,695 barrels were produced. For several years it 

 maintained its rank as third in production until 1915, when the discovery 

 of prolific fields in Texas forced Illinois into fourth place. The decline 

 in production has been offset by the rise in value of the product. Up to 

 the end of 1915 there had been produced from about 230 square miles in 

 Illinois 251,368,311 barrels of oil, with a value of $201,053,017. The 

 new fields that have been discovered in Marion, Clinton, and McDonough 

 counties have not been able to overcome the normal decline in the output 

 of Crawford, Lawrence, and Clark counties. 



1 This paper is one of a series composing a "Symposium on the Geology of Petroleum." 

 See this volnme, p. 156. 



Manuscript received hy the Secretary of the Society May 18, 1917. 



(655) 



