Weathering (physical & chemical) Flashcards
Frost Shatter
Water entering cracks in rocks may freeze > expansion of cracks occurs over time > rocks break apart
Plant roots (vegetation)
Continuous growth of plant roots force the rock apart
Thermal expansion
Hot sun heats the rocks and expansion takes place > heat is lost during cloudless, freezing nights > continuous expansion & contraction of rock can cause it to break apart
(Prominent in desert regions where large fluctuation of temperature occurs between day & night)
Exfoliation
The flaking away of thin layers of rock due to pressure release
Ex:
Rocks formed under great pressure become exposed at the surface when erosion removes surface material > when overlying pressure is removed by erosion, the rock can expand and fall apart
(Can also occur in buildings constructed in desert regions)
Solution (chemical weathering, not river transport)
Falling rain droplets absorb carbon dioxide > mild acid called “carbonic acid” is created
Rocks such as limestone can be completely dissolved by this acid rain
Hydrolysis
Ions of water replace ions of silicate in the rock and the dissolved materials are transported away with the water.
(Water soluble materials and minerals)
Clay is not water soluble, so in areas where hydrolysis is prominent, soils have a high clay content
Oxidation (rust)
Oxygen dissolved in water can change iron into iron oxide.
Rust on rocks or metals
What’s the difference between weathering and erosion?
Weathering is the BREAKING DOWN OF ROCK, and does not involve the transportation of the weathered materials.
Erosion includes the TRANSPORTATION and DEPOSITING of material elsewhere (remove materials from one area and dump them somewhere)
Name the agents of erosion
Water, ice, wind, gravity
What are the types of physical weathering?
Frostshatter, vegetation, exfoliation, thermal expansion
What are the types of chemical weathering?
Solution, oxidation, hydrolysis
