Which of the following does NOT cause weathering of rocks?

Question

a. wind

b. plants

c. animals

Answer 1

Your teacher almost certainly wants you to pick answer C, but the correct answer is "none of the above".  

Wind is an agent of mechanical weathering of rocks.  The wind simultaneously mechanically weathers and erodes rock by blowing sand-sized grains of rock against fresh rock.  This "sand blasts" the rock, often weathering it into distinctive shapes (ventifacts).

Plants are agents of both mechanical and chemical weathering.  Plant roots can force their way into cracks (joints) in otherwise fresh rock, and force the rock apart.  Plant roots, and the microorganisms associated with them (in what is called the rhizosphere) produce organic acids that chemically attack and dissolve rock.

Although most animals do not directly cause the weathering of rocks, there are most definitely some animals that do!  One good example is the chiton, a marine mollusk that eats algae and diatoms that adhere to rocks.  Chitons have very hard, sharp "teeth" (called radula) that are made of magnetite (Fe3O4) that they use to scrape the rocks to which they adhere.  In the process of scraping the rock for food, they also grind off small bits of the rock itself.  If you ever go to a beach where there are chitons, look carefully at the rocks;  you can often see places where the chitons have made depressions or tracks in the rocks as they graze for food.

Chitons are not the only such creature, other marine animals do the same thing.

See source for a reference.  Although the authors of this paper call the process "erosion", it's really weathering.  Erosion is the process of movement of already weathered rock.  Weathering is the process of converting rock into small bits, and that's what the chitons are doing.

Answer 2

The answer is (1) Wind - wind causes erosion and not weathering.

thnks

Answer 3

Deffinately C

=)

Answer 4

c