All the processes that move, elevate or build up portions of the earth’s crust come under diastrophism. These include: (i) orogenic processes involving mountain building through severe folding and affecting long and narrow belt of the earth’s crust; (ii) epeirogenic processes involving uplift or warping of large parts of the earth’s crust; (iii) earthquakes involving local relatively minor movements; (iv) plate tectonics involving horizontal movements of crustal plates. All these processes may be so slow and gradual that they pass unnoticed for a long period of time.