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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.
Decomposed granite is a kind of granite rock that is weathered to the point that the parent material readily fractures into smaller pieces of weaker rock. Further weathering yields material that easily crumbles into mixtures of gravel-sized particles known as grus that further may break down to produce a mixture of clay and silica sand or silt ...
Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs in situ (on-site, with little or no movement), and so is distinct from erosion , which involves the transport of rocks and minerals by agents such as ...
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.
The melting temperature of dry granite at ambient pressure is 1215–1260 °C (2219–2300 °F); [13] it is strongly reduced in the presence of water, down to 650 °C at a few hundred megapascals of pressure. [14] Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present.
Such treatment provides some protection by excluding water and other weathering agents, but it stains the stone permanently. During the renaissance Europeans experimented with the use of topical varnishes and sealants made from ingredients such as egg white, natural resins and silica, which were clear, could be applied wet and harden to form a ...
Working to keep water out and prevent salt buildup, the biocrusts resist chemical weathering, he noted, producing substances that act as a “glue” for soil particles to bind together against ...
One hypothesis is that granite domes are uplifted blocks. This is the case with some granite domes but the fracture related exfoliation joints are what controls the steep slopes. Another theory that regards isolated bornhardts is that they remain after long-distance scarp recession. Moisture related weathering is what causes scarp recession.