86 ILLINOIS ACADEMY OF SCIENCE. 



rence counties, until at the present time, they cover a narrow 

 strip from 2 to 8 miles wide and about 60 miles long, with an 

 area of about 240 square miles. 



Oil was found early in 1908 in a mine near Centralia, Marion 

 County. Prospectors were attracted to the territory and several 

 shallow productive wells were drilled. Later, in 1909, an oil and 

 gas area was tapped north of Sandoval in the same county. This 

 developed rapidly in 1910 and promises at the present time to be 

 an important producer of oil in Illinois. The oil comes from a 

 depth of about 1600 feet in a sand that corresponds to the Kirk- 

 wood of Lawrence County. There are now about 40 producing 

 wells which yield over 3500 barrels daily. 



Oil and gas have been found in small quantities at other points 

 over the State at Greenville, Carlinville, Jacksonville, Pocahon- 

 tas, Marissa, Mascoutah, Eldorado, etc. Active drilhng is now 

 going on at Duquoin, Nashville, Greenville, Carlyle and other 

 localities. 



RANK OF ILLINOIS. 



Illinois gained ninth place for production and value of oil in 

 1906, and third place for both in 1907. Since then the State has 

 held third place for production and second for value and has 

 been excelled only by California and Oklahoma. Up to January 

 1, 1911, about 18,636 wells had been drilled for oil and gas in the 

 State, of which 15 per cent were barren. The remaining 85 per 

 cent have produced since 1905, about 128,000,000 barrels of oil, 

 valued at about $82,000,000. The present daily output of the 

 fields is about 85,000 barrels. The Ohio Oil Company (Stand- 

 ard) controls most of the production. 



THE ORIGIN AND ACCUMULATION OF OIL. 



The origin of oil is uncertain, but two general theories, called 

 the inorganic and the organic, attempt to explain it. One is large- 

 ly unacceptable and even the other has many faults. The inor- 

 ganic theory attributes the origin of petroleum to the breaking 

 down of certain carbides of metals by the action of water in the 

 interior of the earth. It assumes a later condensation of the re- 

 sulting gases as they arose to cooler strata near the surface. 

 This hypothesis does not apply to all oil fields as well as the 

 organic theory. This second theory is based on the decomposi- 

 tion of vegetable and animal matter, particularly in the limestone 

 and shales near the porous sandstones which now contain the 

 oil. It is recognized that plants and animals were deposited in 



