The creation of uplands by movements of the Earth’s crust. This is often, but not necessarily, associated with an orogeny. Possible causes of the uplift of mountains are: a decrease of the density of the crust causing it to rise, possibly above a hot spot; thickening of the crust at collision margins; subduction below continents, causing them to rise; overthrusting of sedimentary rocks during collisions; and compression at converging or at conservative plate margins.