PDF version. These examples illustrate physical weathering: Swiftly moving water Rapidly moving water can lift, for short periods of time, rocks from the stream bottom.
Ice wedging Ice wedging causes many rocks to break. Plant roots Plant roots can grow in cracks. Learn More. What are sedimentary rocks? Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity. Mechanical weathering physically breaks up rock. One example is called frost action or frost shattering.
Water gets into cracks and joints in bedrock. When the water freezes it expands and the cracks are opened a little wider. Home » Discovering Geology » Geological processes » Weathering. Weathering Discovering Geology — Geological processes. You may also be interested in. Discovering Geology Discovering Geology introduces a range of geoscience topics to school-age students and learners of all ages. Geological processes Planet Earth is dynamic with a surface that is always changing.
Erosion Erosion involves the movement of rock fragments through gravity, wind, rain, rivers, oceans and glaciers. Deposition Deposition is the laying down of sediment carried by wind, water, or ice. Rocks sometime expand when exhumed.
Repeated expansion and contraction of the rock during heating and cooling. Sometimes these curved layers fall away like skin on an onion. Soils may also form from transported material derived from elsewhere and deposited in a lowland or basin. Residual soils develop on plains and lowlands with moderate to gentle slopes and consist of loose, heterogeneous material left behind from weathering.
This material may include particles of parent rock, clay minerals, metal oxides and organic matter. This loose material is collectively called regolith , whereas the term soil is reserved for the topmost layer which contains organic matter.
The A-horizon is the topmost layer and is usually a meter or two thick. The upper portion of the A-horizon is often rich in organic matter, called humus , and may also contain inorganic material like insoluble clays and quartz. The A-horizon may take thousands of years to develop depending on the climate and acitivity of plants and animals. This is the layer that supports crops and other types of vegetation. These precipitated minerals often accumulate in small pods, lenses and coatings.
Organic matter is sparse in the B-horizon. The lowest layer constitutes the C-horizon and is comprised of cracked and variably weathered bedrock mixed with clays. Soils can vary significantly in color and composition. The particular type of soil that is produced in a region depends on the available materials, climate and also time. The high temperatures, heavy rainfall and humidity of tropical regions have driven chemical weathering to the extreme. As a result, feldspars and other silicates have been completely altered while silica and calcite is extensively leached from the soil.
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