We explain what erosion is, what this physical process consists of, and how wind erosion and water erosion occur.
What is erosion?
Erosion is the wear and tear exerted over time by the different physical processes of the earth’s surface on the soil, rocks, and materials that could resist them. The main erosive agents are wind, water, ice, and temperature changes.
Erosion is not equivalent to weathering, a process of alteration or disintegration of rocks. For corrosion to exist, a transport of matter or a movement of the same is required, whose repeated passage generates friction and wears on the materials, producing the relief, for example, of valleys, canyons, caverns, plateaus, and other structures in whose formation no the hand of man intervenes.
However, certain human activities can promote or even accelerate erosion. For example, clearing for agricultural purposes removes the topsoil, leaving it uncovered to the action of rain or wind, which in the long run can lead to soil infertility due to loss of nutrients.
In fact, under favorable conditions, erosion can be a strong force in the desertification of soils, contributing to the expansion of 35% of the land surface that is already considered a desert.
On the other hand, wind or water can produce interesting natural monuments: natural arches or peculiar rock formations, such as those in the Salar de Uyuni in Bolivia or the Valley of the Moon in San Juan, Argentina.
This is the name given to the erosion produced by the constant action of the wind over the years, transporting tiny particles of sand or rock that, in continuous friction against soil, stones, and mountains, reduce their outer layers, carving them.
Wind erosion in desert areas is responsible for outlining dunes, displacing them, or forming stone deserts, called “erg.” On the other hand, humid regions usually produce flat or slightly undulating reliefs due to transporting much more delicate materials, such as sedimentary clay deposits.
Water erosion is due to the action of multiple forms of water, from rain, rivers, and seas, and its phase changes according to the weather seasons. Thus, the constant pounding of the waves on the sand on the shore reduces and rounds the pebbles that make up the sand, giving them their characteristic fineness and roundness, which also happens with river stones.
On the other hand, the most prominent rocks resist the impact of the water without moving but gradually lose particles of their outer layer, thus acquiring the roundness and smoothness that usually characterizes them or the holes and craters in which the drops of water fall incessantly.
Likewise, the cliffs, or tidal flats, are the product of the action of the sea over the centuries, just as it happens with riverbeds, in which soil material is eroded and sedimented simultaneously.
The same occurs in glacial regions, in which the movement of the ice, or even its constant formation and melting, impacts the surrounding materials, also causing their wear.