Diastrophism refers to deformation of the Earth’s crust due to diastrophic movements (deforming movements) such as folding, faulting, warping (bending or twisting of a large area) and fracturing. All processes that move, elevate or build up portions of the earth’s crust come under diastrophism. 
They include: orogenic processes involving mountain building through severe folding (crust is severely deformed into folds) and affecting long and narrow belts of the earth’s crust; epeirogenic processes involving uplift or warping of large parts of the earth’s crust (simple deformation); earthquakes and volcanism involving local relatively minor movements; plate tectonics involving horizontal movements of crustal plates. The most obvious evidence of diastrophic movement can be seen where sedimentary rocks have been bent, broken or tilted.