Diastrophism

Diastrophism is the umbrella term for all the processes that move, elevate, or build up portions of the Earth's crust. The word itself carries the core idea: the crust is being deformed, pushed, or raised from within. These are endogenic forces — they originate inside the Earth — and they work on a grand scale, shaping continents and mountain ranges over long geological time.

The book groups diastrophic processes into four distinct types, each acting differently on the crust:

• Orogenic processes — mountain building through severe folding. These affect long and narrow belts of the Earth's crust, where the rock layers get squeezed and crumpled into folds.
• Epeirogenic processes — uplift or warping of large parts of the Earth's crust. Unlike orogeny, this involves broad, gentle movements over vast areas rather than intense local deformation.
• Earthquakes — local, relatively minor movements. These are sudden and short-lived compared to the slow, sustained forces of orogeny and epeirogeny.
• Plate tectonics — horizontal movements of crustal plates. The crust is broken into large plates that drift and collide, driving many of the other processes.

The distinction between orogeny and epeirogeny is central to this section. In orogeny, the crust is severely deformed into folds — the rock layers are bent, compressed, and contorted. In epeirogeny, there may be only simple deformation, meaning the crust is warped or tilted without intense folding. Orogeny is a mountain building process; epeirogeny is a continental building process. So orogeny creates the dramatic, linear mountain chains, while epeirogeny raises or lowers entire continental masses, changing their elevation without crumpling them.

Through all four processes — orogeny, epeirogeny, earthquakes, and plate tectonics — the crust can undergo faulting and fracturing. Faults are fractures where blocks of rock have moved past each other; fracturing is the cracking itself. These structural breaks are a common outcome of the stresses these processes impose. …