4 
BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
logical unit or pool. In consequence the joint ownership or joint 
exploitation of a single pool results in the inability to apportion the 
product on any arbitrary basis of vertical boundary planes, 1 and the 
oil, therefore, is practically no man’s property until it is got above 
ground. This circumstance is almost invariable and the customary 
method of exploiting the single oil pool by a series of small, inde- 
pendent holdings has cost an inordinate toll of waste and loss. 2 The 
economics of oil production is out of adjustment with the geological 
occurrence of oil and the latter, being a physical fact, can not be 
altered. 
ORIGIN. 
Few questions in geologic theory have met with more discussion 
than the origin of petroleum. It is reasonably certain, however, that 
petroleum in the main is of organic origin and represents the natural 
distillation products of plants and animals buried in the muds and 
oozes of ancient swamps and seas. Vast rock formations, indeed, are 
known which are nothing more than the accumulated debris of in- 
numerable organisms, compressed, hardened, and changed into rock. 
Fossiliferous limestones, phosphate rock, and coal seams are familiar 
examples which underlie thousands of square miles of the earth’s 
surface. It would be strange, in fact, if in the process of formation 
oils were not produced, when organic products to-day, subjected to 
heat and pressure, yield oily substances not unlike petroleum. Sedi- 
ments carrying organic remains are sufficiently abundant and wide- 
spread to account for all the petroleum that the oil fields of the world 
give promise of producing. 
DISTRIBUTION. 
While petroleum is of very common occurrence in traces, areas 
underlain by commercial quantities are somewhat restricted and 
fields of great importance are few. Thus in spite of an intensive 
search for new oil regions and vigorous campaigns of development 
carried on in all parts of the world, the entire supply comes largely 
from three countries, as shown in the accompanying chart (fig. 1). 
In the United States, the output is derived from a number of 
widely scattered regions known as u fields,” whose distribution is 
shown on the map (fig. 2), and whose importance is indicated by the 
charts (figs. 7 and 8.) In a broad way, these fields fall into two 
groups — those of the eastern half of the United States, bound into a 
single unit by an extensive system of pipe lines, and those of Califor- 
nia, connected with the rest of the country by railroad transporta- 
1 It is a rather curious commentary on the obsoleteness of American mining law that 
vertical boundaries are applied to oil deposits where they have no meaning, but are not 
applied in the case of outcropping ore deposits, where they are both appropriate and 
desirable. 
2 See fig. 12. 
