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Chapter 7.2 Deserts
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Geologic Processes in Arid Climates
Deserts usually have angular rocks, sheer canyon walls, and surfaces covered in pebbles or sand.
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Weathering In deserts mechanical weathering occurs a lot to shape the land. Because there is not a lot of moisture or precipitation there is not a lot of chemical weathering. There is a little bit of chemical weathering that can happen.
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The Role of Water Most desert streams will be dry and only carry water after it rains, these are called ephemeral streams. Usually these streams only last a few days or hours. These areas are also more susceptible to flash floods.
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Basin and Range: A Desert Landscape
Most of the time the streams formed in a desert area does not flow to lakes or the ocean. They are absorbed by the land. In a Basin and Range area there are small mountain ranges and when there are sporadic rains they move down the mountain and carry a lot of sediment but then settle at the bottom of the mountains and form an alluvial fan – a cone of debris.
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In a Basin and Range area there are times a playa lake can form
In a Basin and Range area there are times a playa lake can form. This is when there is a lot of rainfall or snowmelt and it goes into the center of the basin making a lake. These lakes only last a few days or weeks. When the water dries up the area is called a playa. Water still is responsible for most of the erosion that happens in deserts, wind is a very important factor of erosion in deserts also, but water is the most important.
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