ertain the cause of the slides, and are
features which figure largely in litigation arising from troubles of
this sort.

Both federal and state laws give the right to lateral and vertical
support. When, therefore, adjacent or underlying excavations cause earth
movements in a neighbor's property, litigation is likely to ensue and
the geologist is likely to be called in. The long-wall method of coal
mining, extensively practiced in certain parts of the United States, is
slowly withdrawing support from the ground overlying the coal seams,
resulting in damages to surface structures and in some cases to
overlying mineral deposits. Extensive litigation has been the result,
and the future seems to promise more of it. In certain metal-mining
camps, where considerable amounts of materials have been mined to great
depths, caves and cracking in the surface are reaching over unexpectedly
wide areas, again threatening litigation.

The laws relating to the use of surface and underground waters touch the
geologic conditions in many ways. The permanent lowering or raising of a
water level through mining or damming may require a careful geological
analysis of the underground conditions affecting the movements of
ground-water. The use of streams for placer mining, as in California,
has resulted in formulation of laws and in extensive litigation, again
requiring analysis of geologic conditions.

In fact geologists, perhaps more than any other group, have come to
realize how many and how varied are the ways in which people get into
conflict in using the earth on which they live.

CHAPTER XVII

CONSERVATION OF MINERAL RESOURCES

THE PROBLEM

Conservation of mineral resources may be defined as an effort to strike
a proper balance between the present and the future in the use of
mineral raw materials.

Mineral resources have been used to some extent as far back as evidences
of man go, but great drafts on our resources have come in comparatively
recent years. The use of many minerals has started within only a few
years, and for others the acceleration of production within the past two
or three decades has been rapid (see pp. 63-64). In general, the use of
mineral resources on a large scale may be said to have started within
the lifetime of men still active in business. The wide use of power
necessary to an industrial age, the development of metallurgy, the
increasing size and complexity of demands for raw material, mean that