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Any one studying water must first understand how the Earth evolved and the changes that have taken place in and near Earth's crust. Recent discoveries now demonstrate that the Earth is a dynamic planet. Subtle changes are occurring constantly in the arrangement of continents, the building and destruction of mountain chains, the creation and movement of the sea floor and even the climatic conditions affecting the planet. Geologists now know much about how the Earths' hydrosphere has evolved. It is believed that the Earth formed about 4.5 billion years ago did not have atmosphere, hydrosphere or the familiar, crustal components seen today.
Ideas concerning a plausible theory for evolution of water on the Earth's surface developed within the framework of a theory called "Plate tectonics", proposed in 1912 by Alfred Wegener - a German meteorologist. The theory proposes that the Earth's crust is broken up into a global mosaic of individual plates which vary greatly in size. Some of these plates underlie only the oceanic basins, whereas other make up large, continental land masses as well as nearby ocean floors.
| Parameters | Surfacearea |
Volume |
Volume |
Equivalent | Residence time |
| Oceans and seas Lakes and reservoirs Swamps River channels Soil moisture Groundwater Icecaps and glaciers Atmospheric water Biospheric water | 361 1.55 <0.1 <0.1 130 130 17.8 504 <0.1 | 1370 0.13 <0.01 <0.01 0.07 60 30 0.01 <0.01 | 94 <0.01 <0.01 <0.01 <0.01 4 2 <0.01 <0.01 | 2500 0.25 0.007 0.003 0.13 120 60 0.025 0.001 | ~4000 years ~10 years 1-10 years ~2 weeks 2 weeks-1 year 2 weeks-10,000 years 10-1000 years ~10 days ~1 week |
These plates are in constant motion with respect to one another and depending
upon their configuration they may often collide or keep pulling apart or mere
slipping along one another. When plates collide one of the plates may buckle down
the other and is subjected to partial melting on approaching the high heat zone
at a depth of 80 to 170 km. Because of the melting process of the Crustal plates,
gases such as carbon di-oxide (CO2), Nitrogen (N2) , Hydrogen (H2), Hydrogen Sulphide
(H2S), Sulphur-di-oxide (SO2) and Carbon Monoxide (CO) were released in the accompanying
volcanic eruptions. The principal gas released was water vapor because hydrogen
and oxygen exist in the chemical structure of many rock-forming minerals. When
these rocks are melted, hydrogen and oxygen are released during volcanic eruptions
and unite quickly in the atmosphere to form water vapor.
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