Basic purpose of this article is to Define and discuss on Geothermal Gradients. The geothermal gradient of twenty-five degrees centigrade/kilometer is considered restricted to the upper perhaps the crust. If it continued at this rate uniformly from the surface, the internal temperature of the earth would be over 2,000 degrees centigrade within the lithosphere—a temperature that significantly exceeds the melting temperatures for many rocks at that interesting depth.