Endogenic forces are the internal forces which are responsible for the formation of newundulations on the surface of the earth. Since they create new landforms they are also knownas the Forces of Construction.They are the result of the convectional currents formed in the mantle. The source of this heatis the primordial heat of the interior and radioactive decay of elements.They can be broadly classified into slow forces and sudden forces.Slow forces are of two types – Epierogenic and Orographic.