Temperature Profile:
The continental geotherm is a function of the heat flow entering the lithosphere, the radiogenic heat produced in the lithosphere, the conductivity of lithospheric material, and the surface temperature. The main radiogenic isotopes (U, Th, and K) are concentrated in the upper crust, which explains the curvature on the geotherm in the upper crust. In the lithosphere, heat is exchanged via conduction making the lithosphere a thermal boundary layer. In the asthenosphere, heat is mainly exchanged via convection, a far more efficient process.