Lithosphere is the topmost crust of the earth on which stand our continents and ocean basins. The lithosphere has a thickness between 35to 50 km in the continental regions but becomes thin between 6 to 12 km under ocean beds. In the high mountain region its thickness is estimated about 60km.
though strictly speaking lithosphere includes both land mass and the ocean floors, generally it is used to denote only the land surface which occupies a little less than 30 percentage of total are of the earth. Our knowledge about the interior of the earth is based on the seismic waves as they travel through earth. Scientists have concluded that the centre of earth or earth’s core is a solid sphere with a diameter of about 2,740km. the rocks in this solid core are about three times as dense as those in the crust. Surrounding the inner core of the earth is an outer core, temperature ranges between 2,000 to 5,000 degree Celsius. Between the outer core and the crust of the earth is the dense mantle which is about 2,900km thick.the mantle is mostly solid, but its top some rocks are molten or semi molten. The top most portion of the earth the crust is the land mass comprising soil, sand and rocks. In fact all te sand and much of the soil that we have, has come to us from ancient rocks that have crumbled down under the impact of heat of the sun and cool of the rains a process that has gone on for thousands of years