Salt weathering involves the progressive loss of material on surfaces that are subjected to the cyclic re-crystallization of salts. It is a naturally occurring phenomenon that affects rocks most commonly in desert and coastal environments. Salt weathering also acts on man-made monuments and structures in arid as well as more temperate inter-tidal settings. The crystallization of salts on exposed surfaces produces expansive pressures and material flakes off of these surfaces to relieve the stress. Cyclic heating and cooling as well as wetting and drying drive and exacerbate the flaking, which is why salt weathering is the preferred term for this process. Salt weathering does not typically produce significant cracking within the mass of the element. However, salt weathered surfaces may be aesthetically unpleasing and if left unchecked, could result in significant loss of mass from an element.
Photograph showing sodium sulfate mineralization (white deposits/red arrows) on a foundation stemwall affected by salt weathering. The green arrow indicates the original surface; the scale is in inches.