Spheroidal weathering is a type of chemical weathering

Weathering

Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...

 that creates rounded boulders and helps to create domed monolith

Monolith

A monolith is a geological feature such as a mountain, consisting of a single massive stone or rock, or a single piece of rock placed as, or within, a monument...

s. This should not be confused with stream abrasion, a physical process which also creates rounded rocks on a much smaller scale. A good example of spheroidal weathering can be found in the Alabama Hills

Alabama Hills

Alabama Hills are a "range of hills" and rock formations near the eastern slope of the Sierra Nevada Mountains in the Owens Valley, west of Lone Pine in Inyo County, California....

 area of eastern California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

.

Spheroidal weathering occurs whenever a mass of rock (most typically granitic

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 in composition), experiences a drastic reduction in ambient heat and pressure, such as when a batholith

Batholith

A batholith is a large emplacement of igneous intrusive rock that forms from cooled magma deep in the Earth's crust...

 is exposed at the surface. Rock forms at great temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

s and pressure

Pressure

Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

s (760 °C and 300 MPa, for granitic rock), and in granites there are three mutually perpendicular sets of joints that develop when this overburden is removed. Two things cause this in granites: the quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

 crystals expand about 5%, and acid

Acid

An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ic water attacks the feldspar

Feldspar

Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....

 minerals, turning them into clay

Clay

Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

. Thus the corners become rounded, because angular edges provide more than one area of attack by exposing a greater amount of surface area. Edges and especially corners of an angular block weather faster than flatter surfaces. The ultimate result of this process is a rounded boulder or a dome

Granite dome

A granite dome is a dome of granite, formed by exfoliation.-Formation:Granite forms plutons of igneous rock several kilometers below the surface as magma slowly cools and crystallizes. The granite is under great overhead pressure....

 monolith such as the rounded back of Half Dome

Half Dome

Half Dome is a granite dome in Yosemite National Park, located in northeastern Mariposa County, California, at the eastern end of Yosemite Valley — possibly Yosemite's most familiar rock formation. The granite crest rises more than above the valley floor....

 in Yosemite National Park

Yosemite National Park

Yosemite National Park is a United States National Park spanning eastern portions of Tuolumne, Mariposa and Madera counties in east central California, United States. The park covers an area of and reaches across the western slopes of the Sierra Nevada mountain chain...

.

The process of spheroidal weathering is slower than other common types of weathering such as frost wedging, and it becomes lower still at progressively lower temperatures which slow down the chemical process of feldspar breakdown. Thus many granitic mountain peaks are jagged and crag

Cliff

In geography and geology, a cliff is a significant vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually...

gey instead of rounded.

See also

• Exfoliation (geology)
  Exfoliation (geology)
  Exfoliation joints or sheet joints are surface-parallel fracture systems in rock often leading to erosion of concentric slabs.- General characteristics of exfoliation joints :* Commonly follow topography ....
  
  , a related form of weathering that also creates domes.
• Granite dome
  Granite dome
  A granite dome is a dome of granite, formed by exfoliation.-Formation:Granite forms plutons of igneous rock several kilometers below the surface as magma slowly cools and crystallizes. The granite is under great overhead pressure....