Epirogenesis

Epyrogenesis consists of a parallel movement of the earth's crust on a continental scale. It affects large areas inside the continental plates: platforms and cratons. They are very slow sustained (not sudden) ascent or descent movements that can result in the tilting of a structure. The tilting generates monocline structures (with less than 15º of dip and in only one direction).

They can also result in large, generating aclinal (unfolded) structures. If the bulge is ascending, or positive, it is called anteclise or anteclise; and if the bulge is downward, or negative, it is called sineclise or sineclise. Obviously, rocks of plutonic origin predominate in the anteclise, since it works as an erosion surface, while the sineclise functions as accumulation basins, which is why sedimentary rocks predominate. These structures give the aclinal relief.

Epyrogenesis is distinguished from orogenesis by the greater radius of curvature (or wavelength) of the deformations: the uplift of the soil gives rise to slopes of 1 to 2º in the first case, and from 10 to 70º in the second. second. Epirogenic movements usually occur to compensate for an isostatic imbalance. For example, as the Baltic Shield ice cap melted and receded during the last deglaciation, it has been progressively rising in response to the enormous ice discharge. Many beaches that formed the seashore a few thousand years ago are today 200 m above sea level.