Here's why:
* Marble is primarily made of calcium carbonate (CaCO3).
* Chemical weathering involves reactions with chemicals, like rainwater. Rainwater is slightly acidic due to dissolved carbon dioxide.
* This acidic rainwater reacts with the calcium carbonate in marble. The reaction creates calcium bicarbonate, which is soluble in water.
* The result? The marble dissolves. This process creates smooth surfaces, pits, and even caves, rather than rough ones.
Roughness in marble is more likely caused by:
* Physical weathering: This includes things like freezing and thawing, which can cause the marble to crack and break.
* Abrasion: This happens when particles rub against the marble, such as sand blown by wind.
So, while chemical weathering can change the surface of marble, it makes it smoother, not rougher.
