The snout of a glacier eroded Cape Cod Bay, Massachusetts, and formed the recognizable fishhook shape of Cape Cod itself. Today, in places such as Greenland and Antarctica, glaciers continue to erode the earth. Ice sheet s there can be more than a mile thick, making it difficult for scientists to measure the speed and patterns of erosion.
However, ice sheets do erode remarkably quickly—as much as half a centimeter. Thermal erosion describes the erosion of permafrost along a river or coastline. Warm temperature s can cause ice-rich permafrost to break off coastlines in huge chunks, often carrying valuable topsoil and vegetation with them. Mass wasting describes the downward movement of rocks, soil, and vegetation. Mass wasting incidents include landslides, rockslides, and avalanche s. Mass wasting can erode and transport millions of tons of earth, reshaping hills and mountains and, often, devastating communities in its path.
Some of the natural factors impacting erosion in a landscape include climate, topography, vegetation, and tectonic activity. Climate is perhaps the most influential force impacting the effect of erosion on a landscape.
Climate includes precipitation and wind. Climate also includes seasonal variability, which influences the likelihood of weathered sediments being transported during a weather event such as a snowmelt, breeze, or hurricane.
Topography , the shape of surface features of an area, can contribute to how erosion impacts that area. The earthen floodplains of river valleys are much more prone to erosion than rocky flood channels, which may take centuries to erode. Soft rock like chalk will erode more quickly than hard rocks like granite. Vegetation can slow the impact of erosion. Plant roots adhere to soil and rock particles, preventing their transport during rainfall or wind events.
Trees, shrub s, and other plants can even limit the impact of mass wasting events such as landslides and other natural hazards such as hurricanes. Deserts, which generally lack thick vegetation, are often the most eroded landscapes on the planet. Finally, tectonic activity shapes the landscape itself, and thus influences the way erosion impacts an area.
Tectonic uplift , for example, causes one part of the landscape to rise higher than others. In a span of about 5 million years, tectonic uplift caused the Colorado River to cut deeper and deeper into the Colorado Plateau, land in what is now the U.
It eventually formed the Grand Canyon, which is more than 1, meters 1 mile deep and as much as 29 kilometers 18 miles wide in some places. Eroded sediments have profoundly influenced the development of civilization s around the world. Agricultural development is often reliant on the nutrient -rich soils created by the accumulation of eroded earth.
When the velocity of wind or water slows, eroded sediment is deposited in a new location. The sediment builds up in a process called sedimentation and creates fertile land. River delta s are made almost entirely of sediment that has eroded from the banks and bed of a river.
The rich delta soils of the San Joaquin and Sacramento rivers in northern California, for example, have created one of the most agriculturally productive areas in the world. Loess is an agriculturally rich sediment made almost entirely of wind-blown, eroded sediment. The Yellow River in central China gets its name from the yellow loess blown into and suspended in its water. Human activity altering the vegetation of an area is perhaps the biggest human factor contributing to erosion. Trees and plants hold soil in place.
When people cut down forests or plow up grasses for agriculture and development, the soil is more vulnerable to washing or blowing away. Landslides become more common. Water rushes over exposed soil rather than soaking into it, causing flooding.
Global warming , the current period of climate change , is speeding erosion. The change in climate has been linked to more frequent and severe storms. Storm surge s following hurricanes and typhoon s can erode kilometers of coastline and coastal habitat.
These coastal areas are home to residences, businesses, and economically important industries, such as fisheries. The rise in temperature is also quickly melting glaciers. The slower, more massive form of glacial erosion is being supplanted by the cumulative impact of rill, gully, and valley erosion.
In areas downstream from glacial snouts, rapidly melting glaciers are contributing to sea level rise. Erosion is an easy idea to understand. If you see a rock, pull it out of a mountain. Then throw it down on the ground. You are now a part of the erosion of that mountain. You have taken a big object a mountain and started to make little objects out of it a rock. When that rock hit the ground, it could have cracked and made some tiny pieces of rock sand.
Erosion is just that easy. When it rains, the same process happens. Rocks are washed down a mountain or down a stream. Soils are washed away. The ocean beats against a cliff and breaks it apart. They are all examples of denudation. Things don't just disappear. The masses of dirt and rock are moved to another form and place. Scientists call it mass wasting. Water gets into cracks and joints in bedrock. When the water freezes it expands and the cracks are opened a little wider. Over time pieces of rock can split off a rock face and big boulders are broken into smaller rocks and gravel.
Chemical weathering decomposes or decays rocks and minerals. An example of chemical weathering is water dissolving limestone. When ice melts or wind and water slow down they can't carry as much sediment.
The sediment is dropped, or deposited, in landforms.
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