GEOPHYSICS: G. F. BECKER 
83 
if no energy were dissipated within the continental plateaus, the rate at 
which heat would be conducted from the subterrestrial to the suboceanic 
regions would be exceedingly low.) 
Some of this temperature-excess is probably a remnant of the original 
temperature of the globe equivalent to that which has failed to escape 
because of the low diffusivity of the continental rocks. Another portion, 
probably considerable, represents kinetic energy dissipated in the crush- 
ing and plication of the continental mass. Alas that we cannot evaluate 
the proportion ! 
On the hypothesis under discussion all of this temperature-excess and 
all of the energy of position represents heat which would have been 
radiated into space had all areas of the earth's surface been endowed with 
equal diffusivity. 
The outer shell of the earth down to a depth of perhaps 70 or 80 miles 
at which the primeval temperature still prevails without sensible diminu- 
tion may thus be regarded as an imperfect heat engine receiving heat 
energy at an absolute temperature approaching 2000° and emitting it at 
less than 300*^. The difference is proportional to the energy which would 
be available were this engine perfect. Though far from perfect, it has 
sufficed, it seems to me, to supply what has been expended in maintain- 
ing in part the relatively high temperature of the sub-continental masses, 
and also in epeirogenic and orogenic upheavals, in the shattering and 
crumpling of rocks, and in earthquakes and volcanoes. (It is to be ex- 
pected that the dissipation of energy would be peculiarly intense near 
the surface dividing the rising continental columns from the oceanic 
basins. It is in such positions that most of the volcanoes are found.) 
So far the ocean has been practically ignored, but only a few years can 
have elapsed after the consistentior status before the sea came into being. 
Even a very small difference in diffusivity acting for a very short time 
would have served to outline depressions into which the incipient ocean 
would gather while, after a time at any rate, the presence of the ocean 
with its convective circulation would tend further to increase the differ- 
ence in temperature between the areas of relatively great and relatively 
small diffusivity, which would then become oceanic basins and conti- 
nental plateaus. 
The moment an ocean formed, or rather a moment before it began to 
form, erosion commenced and introduced a new factor into the world 
system. Were the globe completely covered by the sea, evaporation 
and precipitation would furnish no energy of geological significance. 
The energy absorbed in evaporation would be Hberated on precipitation 
and the molecules of water would return to their original level. But 
