Weathering And Soil Flashcards
What is denudation?
Denudation or degradation - the procsess by which rock materials from the earth are removed, resulting the general lowering of the land’s surface
What is weathering
weathering - the procsess by which rocks on the land surface break down or crumble because of the actions of the elements of weather such as rain
, Frost and temperatu
changes
What is erosion
irosion - the procsess by which the whathered materials are transported by agents such as running water, moving ice, waves and wind.
Name 5 factors thats effedt weathering
local climate, mineral composition and structure of rocks , vegatation cover in the area, bare rock swiface and human achvities
What is physical weathering
Weathering
In this type of weathering, rocks break up or disintegrate without any change in their chemical composition.
What is granular disintegratation
Rocks become weak and their grains loosen and fall out because of alternate heating and poling - heating and expansion during the day, and cooling and contraction at night over a period of time, the rocks disintegrate rain by grain. This is called granular lisintegration. It is common in deserts.
What is exfoliation
(b) When the surface layers of rounded rocks and boulders gradually peel off in layers, similar to the peeled layers of an onion, the process is called exfoliation.
When does exfoilation occur
This occurs due to the expansion of the outer layer during the day and the contraction of the same layer during the night, repeatedly over a period of time.
What is chemical weathering
Chemical Weathering or Decomposition the name suggests, chemical weathering volves changes in the chemical composition rocks, which results in their breaking up into maller fragments.
When does chemical weathering take. Place
Usually this takes place when certain minerals contained in rocks react with the gases and moisture in the air.
________ plays an important role in chemicals weathering
Water
What is oxidation?
Oxidation: This is the process by which oxygen in the air reacts with certain minerals in some rocks resulting in the formation of a new chemical compound, which is far more easily eroded..
_____ weakens rocks
Oxidation
How does oxidation weaken rocks?
many rocks contain some amount of the mineral iron. When iron absorbs oxygen from the air, it rusts, changes its colour and becomes a brown or red powdery mass called rust, which is easily eroded. Sometimes, oxygen dissolved in rainwater also acts upon minerals in rocks
What is carbonation
This occurs when carbon dioxide in the atmosphere dissolves in rainwater and forms a new compound called carbonic acid. This new compound reacts with minerals in the rock and causes small pits and grooves on the surface of rocks
What is hydration
This occurs when water itself chemically combines with some minerals present in rocks. Thus, minerals such as feldspar and potash absorb water and become a powdery mass due to the process of hydration, resulting in their erosion.
What is solitions
some minerals in the rocks dissolve in water when rainwater falls on these rocks or when river water flows over them. The soluble minerals dissolve and are removed, resulting in the breakup of the rocks. Rock salt, gypsum, and silica are examples of minerals that are highly soluble.
Some rocks are also weathered by the action of _______
Plants animals and humans
__________ weathering is both physical and chemical
Biological
The decaying remains of dead plants form ______
Organic acids
Name examples of biological weathering
Mining, quarrying, deforestation, tunnelling, road construction, and farming are examples of human activities that result in or contribute to the weathering of rocks.
Name some animals that cause to weathering of rocks
Ants, earthworms, and burrowing animals, such as rats and rabbits, loosen soil and make tunnels and, thus, cause weathering of rocks.
What is frost action
water goes deeper in the crack. Thus, the repeated freezing and thawing results in the deepening and widening of cracks, which break up the rock into angular fragments.
This process is termed frost action.
How is carbonic acid formed
It is formed when CO2 dissolves in rainwater
What is frost action
In the temperate latitudes, the action of frost shatters rocks. Most rocks that suffer frost action have cracks, joints, or pore spaces, and rainwater or snow usually collects in them. During the night, the fall in temperature results in the freezing of this water in the joints and pores. This exerts pressure on the walls of the crack as frozen water expands by one-tenth of its volume.
So the cracks widen and deepen. The following morning, the frost thaws and thewater goes deeper in the crack. Thus, the repeated freezing and thawing results in the deepening and widening of cracks, whid break up the rock into angular fragments This process is termed frost action.
