Carbonation
Topic: Geomorphic Processes: Weathering, Mass Movement, Erosion and Soil Formation · NCERT: Class 11, Ch 5 "Geomorphic Processes"
Meaning
Carbonation is a type of chemical weathering. Rainwater takes in carbon dioxide (CO₂) from the air and soil and forms weak carbonic acid. This acid reacts with limestone and dolomite. It turns them into bicarbonates, which dissolve and are carried away. Unusually, carbonation works faster in cold water, because cold water can hold more CO₂. Over time it creates karst topography, a landscape of caves, sinkholes and underground streams.
Example
The Borra Caves in the Ananthagiri hills of Visakhapatnam district, Andhra Pradesh, were hollowed out of limestone. Slightly acidic water slowly dissolved the rock.
Don't confuse with
- Solution: in solution, a mineral such as rock salt dissolves straight into water. Carbonation needs carbonic acid to first turn the rock into a soluble form.