|
Landslide
is
a mass descent of earth and rock
down the gradient of mountain
slope. Rapid rainfall and
melting snow which acts as the
initiator, sinks through the
earth on the top slope,
penetrating the ‘fault
lines’ such as cracks and pore
spaces in underlying sandstone,
encounters a bed of shale
towards the valley. Accumulation
of water along the upper surface
of the shale, which becomes
loose and softens into slippery
clay. As the grip and foundation
holding the earth weakens,
rapids of earth and rocks slides
down the well lubricated bedding
of shale, scraping the top layer
of fertile topsoil together. In
earlier years, great landslides
move slowly and spasmodically,
causing little destruction.
However currently, due to
excessive logging and mass
emission of acidic gases to the
atmosphere which is the
ingredient for acid rain, barren
and exposed earth and rock,
which are less intact are prone
to external forces of rain can
easily be washed down to the
mountain foot, thereby causing
mass destructions to the
ecosystems below. Mass of earth
and rocks which rush down to
valley would cause silting of
rivers, making the valley more
shallow.
|
|
