page_title: Spall
section_title: Spalling in mechanical weathering
hierarchical_section_title: Spall / Spalling in mechanical weathering
caption_attribution_description: Русский: Морозное выветривание валуна дунитов на гольце Йоко-Довырен в Северном Прибайкалье.
context_page_description: Spall are flakes of a material that are broken off a larger solid body and can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure. Spalling and spallation both describe the process of surface failure in which spall is shed.
  The terms spall, spalling, and spallation have been adopted by particle physicists; in neutron scattering instruments, neutrons are generated by bombarding a uranium target with a stream of atoms. The neutrons that are ejected from the target are known as spall.
context_section_description: Spalling is a common mechanism of rock weathering, and occurs at the surface of a rock when there are large shear stresses under the surface. This form of mechanical weathering can be caused by freezing and thawing, unloading, thermal expansion and contraction, or salt deposition.
caption: Desquamation of dunite boulder
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