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Exfoliating slabs of granite, on Half Dome in Yosemite National Park, USA. Exfoliating granite is a granite undergoing exfoliation, or onion skin weathering (desquamation).The external delaminated layers of granite are gradually produced by the cyclic variations of temperature at the surface of the rock in a process also called spalling.
Exfoliation joints following the topography of inclined valley walls, bedrock hill slopes, and cliffs can create rock blocks that are particularly prone to sliding. Especially when the toe of the slope is undercut (naturally or by human activity), sliding along exfoliation joint planes is likely if the joint dip exceeds the joint's frictional ...
Joints have a profound control on weathering and erosion of bedrock. As a result, they exert a strong control on how topography and morphology of landscapes develop. Understanding the local and regional distribution, physical character, and origin of joints is a significant part of understanding the geology and geomorphology of an area.
Thermal stress weathering is an important mechanism in deserts, where there is a large diurnal temperature range, hot in the day and cold at night. [14] As a result, thermal stress weathering is sometimes called insolation weathering, but this is misleading. Thermal stress weathering can be caused by any large change of temperature, and not ...
Spheroidal or woolsack weathering in granite on Haytor, Dartmoor, England Spheroidal weathering in granite, Estaca de Bares, A Coruña, Galicia, Spain Woolsack weathering in sandstone at the Externsteine rocks, Teutoburg Forest, Germany Corestones near Musina, South Africa that were created by spherodial weathering and exposed by the removal of surrounding saprolite by erosion.
Exfoliation (or onion skin weathering) is the gradual removing of spall due to the cyclic increase and decrease in the temperature of the surface layers of the rock. Rocks do not conduct heat well, so when they are exposed to extreme heat, the outermost layer becomes much hotter than the rock underneath causing differential thermal expansion .
Abrasion is a process of weathering that occurs when material being transported wears away at a surface over time, commonly occurring with ice and glaciers. The primary process of abrasion is physical weathering. Its the process of friction caused by scuffing, scratching, wearing down, marring, and rubbing away of materials.
The presence of such polish indicates that the glaciation was relatively recent (in geologic time scale) or was subsequently protected by deposition, as such polish will be subsequently lost due to weathering processes (such as exfoliation). Low-angle sunlight illuminates glacial polish on granite. Emigrant Wilderness, Sierra Nevada, California ...