Orogeny millions of years and build mountains from plains or from the seabed. The topographic height of orogenic mountains is related to the principle of isostasy, that is, a balance of the downward gravitational force upon an upthrust mountain range (composed of light, continental crust material) and the buoyant upward forces exerted by the dense underlying mantle. Frequently, rock formations that undergo orogeny are severely deformed and undergo metamorphism. Orogenic processes may push deeply buried rocks to the surface. Sea-bottom and near-shore material may cover some or all of the orogenic area. If the orogeny is due to two continents colliding,
Pampean orogeny monzogranites, and volcanic rocks, all of them of calc-alkaline chemistry. The igneous rocks of this belt formed at various times in over the period from 555 to 525 million years ago. From 525 million years ago onward another magmatic belt of peralumineous and mafic rocks developed further amidst gneiss, schist, amphibolites and carbonate rocks. The igneous rocks of this belt formed in the period from 525 to 515 million years ago. The Pampean orogeny can be considered part of the larger Terra Australis orogeny or of the Brasiliano orogeny. The Pampean orogeny developed at a similar time as the Paraguai