276 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1916. 



into account. As these deposits Avill require a distillation process 

 for the recovery of their oil contents, they are not included under the 

 head of free oil deposits, 



Calif omia -field. — California is the greatest producer of petro- 

 leum of any State in the Union. It secures its oil from rocks of 

 Cretaceous to late Tertiary age, the great bulk coming from the 

 Miocene. Nearly every type of structure peculiar to the coast ranges 

 yields commercial quantities of oil, anticlines, domes, plunging anti- 

 clines, monoclines, and fault zones being the principal sources. The 

 reservoir rocks usually are sand and sandstone, though fracture 

 joints in shale hold oil in at least one district. The oil is practically 

 all of asphalt base, although paraffin up to 4 per cent is found in a 

 little of the oil from the Cretaceous and Eocene. The oil varies in 

 gravity from 12° to 35° Beaume (0.9859 to 0.8484 sp. gr.), about 70 

 per cent of it being topped or refined. Much of the heavy oil is used 

 for fuel and road dressing. The productivity of individual wells 

 has reached as high as 58,000 barrels daily ; the average daily p[i'oduc- 

 tion per well was 45.2 barrels in 1913. The oil districts of Cali- 

 fornia are practicall}^ outlined to-day and little in the way of addi- 

 tional acreage is to be expected in the future. 



Alaska field. — Small quantities of oil have been obtained from 

 the Jurassic rocks of western Alaska and the lower Tertiary of 

 eastern Alaska. The oil occurs in sandstone along well-defined and 

 sometimes faulted anticlines. The oil varies in gravity from 39° to 

 45.9° Beaume (0.8284 to 0.7958 sp. gr.) and is of an excellent refining 

 grade. The wells so far drilled are small producers. The commercial 

 productivity of the Alaskan deposits yet remains to be proven. 



Other fields. — In addition to the States mentioned as occupying 

 the above fields, oil occurs in small quantities in Michigan (a con- 

 tinuation of the Petroleo, Canada, field) and Missouri (a continuation 

 of the Oklahoma conditions). These States and Alaska together 

 produced but 7,792 barrels in 1914. Alabama and Mississippi also 

 are said to have possibilities. 



IMPORTANCE OF THE UNITED STATES AS COMPARED WITH OTHER 



COUNTRIES. 



The following table, compiled under the supervision of J. D. 

 Northrop, of the United States Geological Survey,^ giving the pro- 

 duction of crude petroleum in 1914 and from 1857 to 1914, in barrels, 

 illustrates the relative importance of the various oil-producing coun- 

 tries of the world. 



1 Mining and Scientific Press, Aug. 14, 1915, p. 248, 



