Abrasion
Also called: Corrasion · Topic: Geomorphic Processes: Weathering, Mass Movement, Erosion and Soil Formation · NCERT: Class 11, Ch 5 "Geomorphic Processes"; Class 11, Ch 6 "Landforms and their Evolution"
Meaning
Abrasion, also called corrasion, is the wearing away of rock surfaces by the rock pieces that a moving agent carries. Running water, glaciers, wind and waves pick up sand, pebbles and boulders. These pieces then scrape and grind the bed, banks or rock faces like sandpaper. Abrasion greatly increases an agent's power to erode, because clean water or air alone does little damage. It is one of the main ways rivers cut gorges, glaciers scratch and smooth valleys, and wind carves desert rocks.
Example
The Narmada river at Bhedaghat, near Jabalpur in Madhya Pradesh, carries sand and pebbles that grind against its marble bed and walls. Over a long time, this abrasion has helped cut the deep Marble Rocks gorge.
Don't confuse with
- Attrition: in attrition, the carried pieces knock against each other and become smaller and rounder. In abrasion, the carried pieces wear down the bed, banks or rock surfaces.
- Weathering: weathering breaks rock in place, and nothing carries the pieces away. Abrasion only happens when an agent is moving and carrying debris.