Abstract:
Earth scientists have long believed that the present-day volume of the hydrosphere has been stable for a long time and that its changes in the present and future will be extremely small. The earth's water is believed to have been formed by condensation immediately after accretion of the protoplanetary material or to have accumulated at a uniform rate during the course of outgassing and volcanic activity. Thus it is concluded that the present-day dimensions and depth of the ocean are of long standing and became fixed as early as the Precambrian. Based on a study of deep drilling data on shallow-water sequences and basalts from the bottom of the Atlantic, Indian and Pacific oceans and an investigation of their physical properties, the author previously laid the theoretical groundwork for determining the mean rates and magnitudes of the annual inputs of endogenous water to the earth's surface, both at the present time and over the last 160 million years. The determination of the components of free-water balance that were hitherto unknown in the literature is of fundamental importance in evaluating the general direction of evolution of the earth's hydrosphere, the relative areas of land and sea, and as a result, the climate and natural environment on the geologic time scale. The quantities of water derived from the interior and dissipated water, which are insignificant in year-to-year terms, are a permanent factor and largely govern the dynamics of evolution of the earth's surface. These and other aspects of the subject are discussed.