Geophysics" means "Physics of the Earth." While in physics one tries to eliminate the effects of the gravitational, electric, and magnetic fields of the earth, in geophysics these fields, their properties and effects, and the structure and properties of parts of the earth are studied

Gutenberg, B.

Caltech Authors - Main

VoLUME II JULY, 1937 NuMBER 3 
GEOPHYSICS 
A Journal of General and Applied Geophysics 
GEOPHYSICS AS A SCIENCE* 
B. GUTENBERGt 
"Geophysics" means "Physics of the Earth." While in physics 
one tries to eliminate the effects of the gravitational, electric, and 
magnetic fields of the earth, in geophysics these fields, their proper-
ties and effects, and the structure and properties of parts of the earth 
are studied. 
The science of geophysics can be divided into special fields by 
using either the subdivisions of physics, as mechanics, electricity, 
optics etc., or the three major parts of the earth: solid body, hydro-
sphere, and atmosphere. Moreover, in many cases we have "general" 
... as well as "economic" or "applied" ... , problems. In the fol-
lowing tabulation which gives some major problems of geophysics 
by using the divisions just mentioned, general and applied problems 
are given under (a) and (b), respectively. 
Mechanics 
Gravitation 
Solid Body 
(a) Forces and stresses; gradual 
and sudden movements; 
earthquakes, earthquake 
waves, elastic and viscous 
movements; tides; move-
ments of the poles; figure; 
density; volcanism (belongs 
also in other sections and 
geochemistry) ; mechanical 
effects of ice, water, wind. 
(b) Reduction of earthquake 
damaKe ;seismic j)rosiJectinK 
(a) Gravity; layering; pressure; 
isostasy; sedimentation 
(b) Use of pendulum, torsion 
balance, etc., in prospecting I 
--------~---------
Hydrosphere 
(a) Tides, waves, 
currents; hy-
drology 
(b) Investigation 
and prediction 
of tides and 
currents for 
navigation and 
fisheries; h y-
drology; echo 
sounding 
Atmosphere 
(a) Tides, waves in-
cluding sound; 
currents 
(b) Weather fore-
casting 
(a) Layering; sedi- (a) Distribution of 
mentation gases; layering 
*Resume of a paper read at the Annual Meeting at Los Angeles, March, 1937. 
tBalch Graduate School of the Geological Sciences, California Institute of Tech-
nology, Pasadena, California. Contribution No. 224. 
r8s 
r86 B. GUTENBERG 
Solid Body Hydrosphere Atmosphere 
--------
Electricity (a) Electric currents and elec- (a) Electric phe- (a) Electric phe-
tric waves nomena nomena; iono-
(b) Electric prospecting sphere; aurora 
Magnetism (a) Earth's magnetism (b) Compass; mag-
(b) Magnetic prospecting netic charts 
Optics (a) Color and trans- (a) Meteorological 
parency of optics, halos 
lakes, oceans etc.; color of 
sky; polariza-
tion; turbidity; 
colors of clouds. 
j(b) Visib!Jity for 
a VJatwn. 
Composition (a) Composition of the earth; (a) Radioactivity 1(~)(:-;;-~osition of 
of matter radioactivity; state of the of hydrosphere; I the atmosphere, 
interior salt content ozone, etc. 
Heat (a) Temperature in the earth (a) Temperature in (a) Thermodynam-
and its changes; crystaliza- lakes, rivers ics of the at-
tion and melting and oceans; mosphere; tern-
(b) Thermal prospecting glaciers; ICe- perature; eli-
bergs; thermal mates (include 
currents other factors) 
(b) Climatology 
The entire science of Geophysics as sketched above is seldom con-
sidered as a separate division of knowledge, comparable to geology or 
astronomy. One reason for this attitude is the fact that no one person 
can be familiar with all parts of the geophysical field. Usually, geo-
physicists either specialize in problems concerning the solid earth, or 
in oceanography, hydrology or meteorology; some are more familiar 
with general geophysics, others with economic problems; some prefer 
questions of mechanics, others of electricity. However, there are many 
problems which occur in wholly different sections of geophysics, but 
which require almost the same theoretical treatment. The same equa-
tions are to be used for the propagation of earthquake waves, explo-
sion waves in seismic prospecting, in echo sounding in the ocean, 
and for the investigation of the so called "anormal sound waves" in 
the atmosphere. Many problems of oceanography and meteorology 
are similar. In several respects the ocean is an image of the atmosphere 
with a disturbed layer near the surface of the earth, followed by a layer 
with decrease in temperature and finally a relatively quiet layer (strat-
osphere). 
Geophysics is a very young science, and this is another reason for 
GEOPHYSICS AS A SCIENCE 
its not being considered as a separate division of knowledge. Meteor-
ology separated relatively early from the science of the "meteors." 
Oceanography has developed in most countries under the national 
departments of commerce to reduce the dangers of navigation. Seis-
mological observatories can be found today as a part of geological, 
geographical, astronomical, meteorological, mining, and engineering 
observatories and departments. As a rare exception, the Saint Louis 
University may be quoted, where geology belongs to the department 
of geophysics. 
The relationship between geology and geophysics has been dis-
cussed frequently. There can be little doubt, however, that geophysics 
and geology must cooperate to get a maximum of results. This is a 
fact from the viewpoint of geology as well as of geophysics, and for 
problems concerning the structure of the earth's crust as well as for 
investigations concerning local problems of economic importance. 


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