Terrestrial areas land surface

We have already discussed where there is water and how it is distributed on Earth. Our Earth is the largest of the terrestrial planets. The mass is 5.97 x 10 kg, the density 5.5 gcm . The oceans comprise 2/3 of its surface. Over the whole evolution, the mass of land has increased steadily, during the past two billion years, the total area of the continents has doubled. Like the other terrestrial planets, the interior of the Earth can be divided into layers the lithosphere is found at a depth between 0-60 km, the crust between 5 and 70 km, the mantle between 35 and 2890 km, the outer core between 2890 and 5100 km and the inner core between 5100 and 6371 km (density 12 gcm ). The geothermal gradient is the rate of increase in temperature per unit depth in the Earth. This internal heat is produced by radioactive decay... 

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