As pressures are released by the removal of overlying rocks (due to weathering and erosion over long periods of time), small to large, often curved, slabs of rock break off from the original rock mass under the influence of gravity.
(pressures; are released; by the removal of overlying rocks (due to weathering and erosion over long periods of time) (small to large, often curved, slabs of rock; break off; from the original rock mass)
pressures small to large, often curved, slabs of rock
are released break off
by the removal of overlying rocks (due to weathering and erosion over long periods of time
from the original rock mass