You modern folding – also called tertiary folding or corogenic adeias – are a type of province or geological structure that, as the name indicates, has a recent formation. These folds basically consist of the great mountain ranges existing on the planet, such as the Andes Mountains, in South America; the Alps in Europe; the Rockies in North America; the Himalayan Mountains in Asia; among other cases.
The formation of modern folding occurred thanks to the orogenetic movements of the Earth's crust, which are characterized by the collision between two tectonic plates, being geologically fast and forming unstable areas. The beginning of the formation of the Earth's major mountain ranges did not occur until 250 million years ago, during the Tertiary period.
As they are areas of geologically recent formation, the modern folds are still undergoing a slow erosion process, given that there was not much time for external or exogenous agents to act in the sense of shaping their forms. In the case of old folding, for example, this process has already occurred, which gave rise to numerous plateau areas and also contributed to the origin of sedimentary basins.
See below an explanatory scheme for the formation of modern folds:
Explanatory scheme of the formation of modern folds
As they consist of areas positioned at the meeting between two tectonic plates, modern folding they are usually accompanied by geological faults and present occurrences of intense and strong volcanism earthquakes. The predominant rocks in these areas are igneous and metamorphic, given that sedimentary rocks are recurrent in older areas.
Modern folding is therefore an example of how land relief is a dynamic component, which is constantly changing. Today these mountain ranges represent the highest altitudes in the world, but in a few million years they will be lower and may even turn into valleys or flatter areas.
By Rodolfo Alves Pena
Graduated in Geography
Source: Brazil School - https://brasilescola.uol.com.br/geografia/dobramentos-modernos.htm