244 
tant petroleum resource, then, for the 
people of North America is that which 
at present is both undrilled and un- 
discovered. 
A geologist does not physically “see”’ 
an oil or gas field any more than a 
meteorologist, for example, sees a low- 
or high-pressure area even though both 
commonly use contour lines to describe 
the ideas they intend to convey. Both 
are presenting mental concepts of the 
conditions as they are thought to exist. 
Until a discovery well has been 
drilled, any undiscovered oil or gas 
field at best exists only as an idea in 
the mind of the geologist. In a like 
manner, the basis for any undiscovered 
petroleum province—a petroleum pro- 
vince being a region in which there 
are a number of oil and gas pools 
having related geological conditions— 
the basis for such an undiscovered 
province exists only in_ geologic 
thought. It is rather sobering to 
remember that the future of this great 
natural resource—upon which many 
national and continental policies are 
based, industries planned, and de- 
defenses built—should rest in the 
mind and in the imagination of the 
geologist. Our petroleum resources 
will not be exhausted until after our 
imaginative powers have been ex- 
hausted. Our job is cut out for us! 
There has been a great deal written 
about petroleum geology—what it is, 
how it is applied and what it can 
accomplish. A crude idea of the phil- 
losophy underlying the search for an 
oil pool, may be stated in three words: 
“Find a trap.” Some would add the 
word “‘first,” to cover the competitive 
element. As might be expected, such 
a definition suffers from over-simpli- 
fication, but it does contain the under- 
lying objective of nearly all petro- 
leum-exploration geology and geophys- 
ics. Prejudices against fresh water, 
red sediments, continental beds, high- 
carbon ratios, lack of source rocks, 
closeness to the mountains, and lack 
of sands fade rapidly in the face of a 
good trap. 
It so happens, however, that traps 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
are neither simple nor easy to find. 
They vary from wholly stratigraphic 
to wholly structural in character and 
from Ordovician to Pleistocene in 
geologic age. They are not the same 
at depths of 10,000 and 15,000 feet 
and below several unconformities as 
they are near the surface; nor are they 
the same in the centers of the basins 
as they appear on the outcropping 
flanks. Seldom is a prospective trap 
found with more favorable character- 
istics than unfavorable. As a matter 
of fact, the final decision as to whether 
to lease and drill a prospect often 
depends on extremely tenous and hazy 
geologic data, and drilling can be 
justified only on the basis of experience, 
imagination, and daring. 
Moreover, the average trap is merely 
the container of one oil field, which in 
the continental picture is insignificant 
in terms of the over-all requirements. 
Some oil fields, it is true, are large 
enough to supply substantial amounts 
of oil—up to 1 or 2 years’ needs—but 
they are rare. Of the 400 to 500 oil, 
gas, and condensate fields discovered 
each year, most are relatively small— 
half a million to several million total 
barrels—or only enough to take care 
of the needs of days or even a fraction 
of aday. Of the more than 3,000 pro- 
ducing oil fields found so far in North 
America, only slightly more than 100 
originally contained more than 100 
million barrels of oil, an amount which 
it should be remembered is only 20 
days’ consumption. The trend during 
recent years has been in the direction 
of more annual discoveries but with 
smaller-size pools, and it is this trend 
of small discoveries which gives alarm 
to many persons. To solve the prob- 
lem effectively, our thinking must be 
in terms of provinces. 
The presently active provinces such 
as the Gulf Coast, West Texas, the San 
Joaquin Valley, the mid-continent 
States, and the Rocky Mountain re- 
gion can all be expected to continue 
to provide new oil and gas fields for 
many years to come. The prospects 
for further discovery in these areas are 
