Frost wedging, when water gets inside the joints, alternate freezing and thawing episodes pry the rock apart
Salt crystal growth, force exerted by salt crystal that formed as water evaporates from pore spaces or cracks in rocks can cause the rock to fall apart
Abrasion, wearing away of rocks by constant collision of loose particles
Biological activity, plants and animals (including humans) as agents of mechanical weathering
Dissolution, dissociation of molecules into ions; common example includes dissolution of calcite and salt
Oxidation, reaction between minerals and oxygen dissolved in water
Hydrolysis, change in the composition of minerals when they react with water
Climate, areas that are cold and dry tend to have slow rates of chemical weathering and weathering is mostly physical; chemical weathering is most active in areas with high temperature and rainfall
Rock type, the minerals that constitute rocks have different susceptibilities to
weathering
The susceptibility of minerals (from high to low) roughly follows the
inverse of the order of crystallization of minerals in the Bowen’s reaction series
Olivine which crystallizes first is the least resistant whereas; quartz which crystallizes
last is the most resistant.
Rockstructure, rate of weathering is affected by the presence of joints, folds, faults,
bedding planes through which agents of weathering enter a rock mass
Highly jointed/fractured rocks disintegrate faster than a solid mass of rock of the same
dimension
Topography, physical weathering occurs more quickly on a steep slope than on a
gentle one
On a gentle slope, water may stay longer in contact with the rocks, hence chemical weathering is enhanced.
Time, length of exposure to agents of weather determines the degree of weathering