weathering

weathering

process that breaks up and corrode solid rock, eventually transforming into sediment

physical weathering

process in which intact rock breaks into smaller grains or chunks

erosion

grinding away and removal of earths surface materials by moving water, air, or ice

frost wedging

when water trapped in a joint freezes, joints open, creating more fragments

salt wedging

When salty water seeps into the rock and then evaporates, salt crystals form and expand, pushing against the rock to break apart rocks

root wedging

as roots grow, they apply pressure to their surroundings and can push joints open

thermal expansion

when rocks are repeatedly heated and cooled, causing the minerals within the rock to expand and contract, creating fragments and fractures

chemical weathering

process in which chemical reactions alter or destroy minerals when rock comes in contact with water solutions or air

types of physical weathering

root wedging, frost wedging, salt wedging, thermal expansion

dissolution

where acidic water breaks the bonds in certain minerals, causing them to dissolve and be carried away in solution

hydrolysis

water reacts chemically with minerals, breaking them down to form new minerals

oxidation

where minerals react with oxygen, causing elements like iron to rust

hydration

the absorption of water into the crystal structure of minerals causes some minerals, such as certain types of clay, to swell.

feldspar hydrolysis reaction

feldspar + carbonic acid + water
→ clay minerals + dissolved ions

feldspar hydrolysis

When feldspar reacts with slightly acidic water, hydrogen ions replace potassium in the feldspar structure. This process breaks down the feldspar, forming clay minerals (kaolinite) and dissolved ions that are carried away by water.

controls on weathering

rock composition, climate, surface area, presence of a soil, time