When the diurnal rotation of the Earth is accelerated, on the other hand, the increase in the centrifugal forces makes the planet more elliptical in shape. At this time the Earth appears to be in a phase of expansion, and material is transferred from high latitudes to low latitudes. Tectonic movements characteristic of an expanding planetary surface then take place in the Earth's crust*. During the expansion stage the area of the crust will increase, as a result of the outpouring of subcrustal material into faults and cracks which have been formed. It may be that these newly appearing parts of the Earth's crust subsequently become stronger than some of the "old" parts.
If this is indeed the case, then it implies the following interesting regularity in the evolution of the Earth's crust: as time goes by, the crust is apparently renewed during the expansion stages, as a result of the appearance of "new" regions, which later become the ocean floor. During the contraction stages, on the other hand, the crust becomes thicker because of the "old" regions. Could this not have been the means by which the Earth's surface became differentiated into continents and ocean basins? In general, the fluctuating inertial-gravitational forces which cause the world to pulsate along its diurnal-rotation axis give rise to mainly horizon tal tectonic stresses. However, it must be remembered that climatic changes and oscillations of the Earth's angular velocity also produce forces which give rise to tectonic movements which are mainly vertical. These forces are isostatic in nature, and they appear as a result of the redistri bution of the water masses on the Earth's surface in the meridional direction (the appearance or disappearance of solid-phase water, and shifting of the hydrosphere under the influence of the centrifugal diurnal rotation forces). Consequently, the general planetary hypsometric curve varies with time, since the relative elevations of the ocean floor and the continents vary periodically, being different in different regions.
Thus, geotectonic movements are mainly the results of two phenomena involving the entire planet: the axial pulsation of the world caused by variations in its angular velocity; and the isostatic equalization associated with an increase or decrease in the water stress on different segments of the Earth's surface.
The various tectonic movements will result in a rearrangement of the structure of the Earth, a transformation of its surface topography, and a consequent variation in the vertical-horizontal ratios between water and dry land. In addition (and this should be emphasized), the ratio between
water and dry land will not only be determined by the dislocation move ments but also by the shift of the hydrosphere relative to the lithosphere, resulting from variations in the centrifugal diurnal-rotation forces. Thus, this ratio is determined directly by the tectonics, and also by the diurnal rotation regime. However, the variations in the vertical-horizon tal ratio between dry land and water are still the main factor leading to a planet-wide rearrangement of the hydroatmospheric circulation, and thus giving rise to new climatic conditions.
On the basis of all the foregoing, we can draw the following conclusion: a definite cause-effect relationship exists between the three main factors influencing the evolution of the Earth (climate, diurnal-rotation regime, and tectonics). Periodic redistributions of the water mass relative to the diurnal-rotation axis (as a result of hydroatmospheric processes driven by the solar thermal energy) are the chief cause of the relation-interaction between these factors. The main elements of the mechanism responsible for redistribution of the water mass on the Earth's surface are: the ellipsoidal shape of the Earth (the curvature of its surface); the presence of an atmosphere; the arrival of thermal energy from the Sun; and the presence of cold in interplanetary space. This mechanism can be represented as a kind of heat engine, with a planetary boiler in the low latitudes and a refrigerator in the high latitudes.
Let us denote the cause-effect relationship between climate, diurnal rotation regime, and tectonics as the first-order regularity in the evolution of our planet.
The three envelopes of the Earth (atmosphere, hydrosphere, and lithosphere) will obviously react in different ways to changes in the rota tional regime of the Earth. The hydrosphere, which is more mobile, will assume its new shape quickly. The lithosphere, on the other hand, will change shape only after some lag period, as determined by the physico mechanical properties which govern the relaxation time. The atmosphere, whose rotational regime is also modified (by friction), changes shape as well, but not at the same time as the hydrosphere and the lithosphere. Thus, by virtue of the differences in the physicomechanical properties of the geospheres, the figure of the Earth will at any given moment have a kind of triple nature, as a result of fluctuations in the length of the terrestrial day.