Denudation Process

Denudation

Denudation - demolition of weathered material, by means of flat flushing and gravitational movements, and after their accumulation on the surface. Dementation agents are: gravitational movement, running water (water erosion), underground and surface water (karst, suffusion), snow and ice (nivalation, examination), wind (deflation), surf (abrasion), living organisms (human). The intensity of denudation is determined by the amount of sediment carried by rivers, glaciers per unit time. Denudation forms of relief are:

Ground

• Proper denudation

In a broad sense - the surface emerged, due to the combined effect of the entire complex of denudation processes (for example: peneplain or various structural-denudation forms.

In the narrow sense - the surfaces exposed, due to gravitational movements and flat flushing (pillars, niches, cornices, canopies)

Peneplen - slabovolshlennaya plain, formed in the process of prolonged denudation on the territory of the ancient mountains. This term was first introduced by the American geologist William Morris Davis, in the nineteenth century. The process of denudation took place in a humid climate (the amount of precipitation is greater than it can evaporate and soak into the soil, because of this, many streams and rivers are formed, increasing erosion in this area).

Cornices - snow formations in the mountains, arising from the action of winds on ridges and peaks.

The niche is a recess in the lower part of the ledge of the abrasion bank, which results from the destructive effect of the surf flow.

• Erosion - the surface produced by running water (valleys, erosion terraces, ledges).

The ledges are part of the rock mass in the form of a step prepared for the development of a mineral deposit.

The erosion terrace is a terrace composed of bedrock and covered with low-power alluvium. This is the most ancient type of terraces, which is distinguished by its high altitude.

• Abrasive - worked out by sea and lake abrasion (ledges, benches, niches, abrasion terraces).

Abrasive terraces (benches) are the coastal part of the seabed surface , produced by abrasion.

• Exacerative - produced by glaciers (plains, troughs, sheep's foreheads).

The trogs are a valley in the ancient glacial region with a trough-shaped transverse profile, a wide bottom and steep concave sides, which are associated with the smelling activity of glaciers. In the longitudinal profile, the trough valleys usually have a stepped form, where the over-deepened sections (ploughing basins) alternate with raised rocky steps (crossbars).

Lamb's foreheads are rounded protrusions of rocks formed by the action (movement) of the glacier. Several nearby small sheep's foreheads are sometimes called curly rocks. In Russia, they are distributed in the area of the Baltic shield (the Kola Peninsula). The surface of mutton foreheads is covered with a thin layer of turf and shallow talus, easily shifting under load and slippery due to the oozing water.

• Nivalnye - created at the snow border (line), due to frost weathering (nivatsionnye niches, cars, circuses).

Kary - one of the forms of relief, representing the cup-shaped depression in the pre-hill part of the slopes of the mountains. The cars have steep side walls and a flat bottom, occupied by a glacier with a cluster of firn and snow. At the edge of the car there are crossbars.

Circus - hollow in the mountains, closing the upper end of the glacial valley.

• Deflationary - emerged under the influence of wind (niches, mesh, honeycomb, eolian mushrooms, sore-deflation depressions).

Eolian fungi - a form of relief, resulting from the activities of wind and corrosion. Since the wind carries the particles mainly at the surface, the lower parts of the rocks are grinded and processed by the wind more strongly. So there are eolian forms of relief, reminiscent of pillars or mushrooms on a thin stem.

• Karst - arose as a result of dissolution (ponora, funnel, hollow, cave).
• Technogenic - emerged in the process of human production (canals, mines, embankments).

Underwater

1. Gravitational (landslides).
2. Erosion (underwater valleys, canyons).

Underwater canyons are valleys with steep slopes, cut in the continental shelf and continental slope. Some of them represent an underwater continuation of the mouths of rivers, others are not related to the current rivers. From the mouth of the Ganges for 1000 miles to the Bay of Bengal , an underwater canyon 7 km wide and more than 70 m deep extends. Canyon r. Congo can be traced at a distance of 260 km to a depth of 2150 m. Hudson begins a canyon, stretching towards the sea for almost 400 km. In the Pacific coast of the USA, the shelf is very narrow, and the canyons here are deep and have steep slopes. The canyon of Monterrey off the coast of California is sometimes compared to the Grand Canyon.