what causes rock to break down?
2007-02-07 11:29:40 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Earth Sciences & Geology
There are 2 types of weathering and erosion: Mechanical and Chemical.
Mechanical is physical disintegrating. Smaller pieces are formed, cliffs break off into pebbles and the pebbles into sand. Only the size changes, not the chemical composition. Frost, wetting and drying, wind, water, plants and animals, and roots are part of mechanical erosion. When water freezes, it has an unusual property. Most materials expand when heated and contract when cooled. This is true of water as well, except when it is cooled from 4*C to 0*C. At these temperatures, water expands. Water expands most when it solidifies into ice. WHen water becomes ice, it takes up 9%-10% more space. This exerts incredible pressure on rocks and then splits apart rocks. When water gets into tiny pores, it is called ice wedging or frost action.
Rainwater, oxygen, carbon dioxide, and plant decay acids are all examples of chemical erosion. These are called agents.
Hydration and Hydrolysis is a chemical reaction of water and other substances. Hydration is when water combines with another substance. An example is the hydration of anhydrite turning into gypsum.
2007-02-07 14:11:42 · answer #1 · answered by dreamoutloud2 3 · 0⤊ 0⤋
Breaking down of rock is usually caused by weathering. However,some rocks may break down due to radioactive decay.
Weathering can occur in several forms, including, chemical reaction with water which can cause rusting. Natural acids such as carbonic, humic, and sulfuric acids break down rocks. Physical weathering can break down rock through freeze/thaw action. Also, exfoliation of rock due to unloading after deep burial can cause rocks to break down.
2007-02-07 19:54:58 · answer #2 · answered by TheBodyElectric 3 · 0⤊ 0⤋
Any number of things.
Erosion from water or wind.
Expansion and contraction of the rock due to extreme temperatures.
The softer the rock, the quicker it erodes. Therefore, rocks such as sandstone are going to be more susceptible to erosion than a rock such as granite.
2007-02-07 19:40:06 · answer #3 · answered by Huevo 6 · 0⤊ 0⤋
Tanic acid from organic material, such as tree leaves can react with limestone and make sinkholes.
2007-02-07 20:40:21 · answer #4 · answered by ozywadle 3 · 0⤊ 0⤋