f all drilling records is a highly desirable
procedure in the interests of the development of the mineral industry as
a whole. A vast amount of unnecessary duplication can thus be avoided.
The record of a drill hole, even though barren, may be of vast
significance in the interpretation of future developments and should be
recorded as carefully as an abstract of land title. The property right
of the explorer in such information can be and usually is protected by
withholding the record from public inspection until sufficient time has
elapsed to give him full opportunity to use the information to his own
best advantage.

The opportunities for cooperation with specialists of public
organizations are almost unlimited. These organizations are likely to
have an accumulation of data and experience extending through long
periods and over large areas, which the private explorer ordinarily
cannot hope to duplicate. With proper restrictions this information may
be available for public use. A good illustration of current cooperative
effort of this kind is in the deep exploration for oil in the Trenton
limestone of Illinois. Outcrops and other specific indications are not
sufficient to localize this drilling; but the information along broad
geologic and structural lines which has been collected previously by the
Illinois Survey is sufficient so that, with a comparatively small amount
of shallow drilling, the locus of the more favorable structural
conditions may be determined. In this case the Survey is directing the
initial exploration, which is financed by private capital.

ECONOMIC FACTORS IN EXPLORATION

The approach to the problem of exploration is very often determined by
local requirements and conditions; but if one were to come at the
problem from a distance and to keep matters in broad perspective, the
first step would be a consideration of what might be called the
_economic factors_. Let us suppose that the geologist is free to choose
his field of exploration. An obvious preliminary step is to eliminate
from consideration mineral commodities which are not in steady or large
demand and are much at the mercy of market conditions, or which are
otherwise not well situated commercially. The underlying factors are
many and complex. They include the present nature and future
possibilities of foreign competition, the domestic competition, the
grades necessary to meet competition, the cost of transportation, the
cost of mining u