Carbonation is the reaction of carbonate and bicarbonate minerals and is a common process helping in breaking down of feldspars and carbonate minerals.  

• Carbon dioxide from the atmosphere and soil air is absorbed by water, to form carbonic acid that acts as a weak acid.  

• Calcium carbonates and magnesium carbonates are dissolved in carbonic acid and are removed in solution without leaving any residue resulting in cave formation. 

Source: NCERT – XI Fundamentals of Physical Geography