Isostacy:It is the state of gravitational equilibrium between Earth’s crust and mantle such that the crust”floats” at an elevation that depends on its thickness and density.Related to differences between oceanic crust, continental crust, and the mantle, is the principleof isostasy. In simplest terms, the lithosphere is “floating” on the denser, deformable,asthenosphere below. The addition of a significant amount of mass onto a portion of thelithosphere causes it to sink, whereas the removal of a large mass allows the lithosphere to rise.
Diastrophism:It refers to deformation of the Earth’s crust, and more especially to folding and faulting.Diastrophism can be considered part of geotectonics. Diastrophism comes from the Greek wordmeaning a twisting. All processes that move, elevate or build up portions of the earth’s crustcome under diastrophism.
Exfoliation:One of the most striking of all weathering processes is exfoliation, in which curved layers peeloff bedrock. Curved and concentric sets of joints develop in the bedrock, and parallel shells ofrock break away in succession, somewhat analogous to the way layers of an onion separate.The sheets that split off are sometimes only a few centimeters thick; in other cases, however,they may be several meters thick.