All types of weather affect the earth.
Rock disintegrates because of exposure to weather elements, such as water, wind and heat. Weathering, therefore, is weather-related. Weathering only happens to the rocks near the earth's surface; it does not happen in the deep underground. The vital process of weathering carries and provides the nutrients for soil, as it releases and deposits the minerals needed for plants. This process has shaped our earth.
Factors That Influence Weathering
Porous sandstone is easily affected by weather.
Rock that is hard or solid and does not have cracks is resistant to weathering. Soft or porous rock, with cracks and joints that let water in, is not resistant to weathering. For example, granite is a hard rock and is resistant to weathering. Sandstone, which is more porous, is easily affected by the weather. Limestone, which is a rock composed of calcium carbonate mineral, dissolves easily and weathers easily.
Geographic orientation is a factor of weathering. Facing north or east, rock gets less heating or cooling from the sun. Rocks that face this direction weather slower than south- or west-facing rocks. An example is on North American houses, shingles facing north and east last longer.
Climate plays a huge role in weathering. If you live in an area that is moist, physical weathering becomes very important to the integrity of rocks.
Elements of Weathering
Water brings its own design to rock.
The different elements of weathering, including heating and cooling, pressure release, wedging, crystallization and frost action, are responsible for natural weathering occurrences.
Heating and Cooling
Temperature changes cause rocks to stress as they expand and contract. This change in the rocks causes fractures. As time goes on, pieces of a rock's layers break off.
Pressure Release
When rocks experience the great weight that occurs as pressure is released, this allows rocks to grow and crack or break. The breaks are caused by the stress placed on the rock.
Wedging
The roots of plants growing in rock cause cracks. As the roots growing in the rocks get larger, they cause the rocks to actually fracture.
Crystallization
When water deep inside a rock is brought up to the surface and then evaporates, it causes crystallization. This process causes fractures in rocks. The crystals are dissolved mineral salts that expand, causing the fractures.
Frost Action
In rocks that have cracks, water collects, and, as this water freezes and thaws, the rock is weakened. This action of freezing and thawing causes rocks to break.
Chemical Weathering
Quartz is the end product of hydrolysis.
Hydrolysis, oxidation and carbonation are components of chemical weathering.
Hydrolysis
Hydrolysis is the process of hydrogen reacting with carbon dioxide and other minerals to chemically break down the rock into silica, or quartz. As the weathered materials are washed downstream, they turn into clay deposits. The process that weathers granite and basalt is a slow one.
Oxidation
Oxidation is when oxygen mixes with minerals and forms oxides. This creates a natural rusting. As iron rusts, it breaks apart. Rock decomposition occurs as a process of oxidation.
Carbonation
When water mixes with rocks containing carbon, like limestone, the process produces carbonic acid solution. This acid water dissolves vegetation that is rotting. The water also washes out as acid rain. The acid then breaks down the rock and dissolves it.
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