This happens when rocks disintegrate into large blocks and other smaller fragments and particles without changing any of their constituent minerals. Physical or mechanical weathering are caused by these agents:
Expansion – This leads to exfoliation.
Crystal growth or frost action – This leads to block disintegration in temperature latitudes as well as on high mountains.
Thermal Expansion and Contraction – This is usually common in desert lands where changes in temperature are great.
Organic or Biological activities – Plant and animal decay lead to formation of acids which help in rock break-up.
Colloid Plucking – This is a form of minor physical or mechanical weathering and not common generally.