Definition of Weathering:
Alteration of rocks due to action of surroundings such as wind is known as weathering.
It is of two types
Movement and removal of products obtained by weathering is known as erosion.
Weathering of earth’s surface is known as denudation.
Mechanical breakdown of rocks is known as physical weathering.
Chemical alteration of rocks is known as chemical weathering.
When weathering occurs rocks are turned into thin layers or sheets and gives round mass . This process is known as exfoliation.
Geological time scale:
Chronological sequence of rocks is known as geological time scale. It is widely accepted in Europe. By chronological sequence it means the sequence in which one thing comes after other with time.