How is a gorge formed from a waterfall
How a Waterfall is formed - labelled diagram and explanation
hello everyone in this video we can be
looking at an erosional River feature
this River feature occurs in the upper
part of the river and is called a
waterfall now with a waterfall there are
two different types of rocks that are
needed for a waterfall to form and they
form in a layer as you can see labeled
on the diagram the top layer should be a
hard layer and this is more resistant
Rock that is less prone to erosion and
the bottom layer was a soft rock which
is less resistant Rock and more prone to
rapid erosion then when the water comes
off the top of the hard rock layer and
crashes down onto the soft rock layer as
you can see over here it tends to form a
plunge pool so the velocity and the
strength of the water enhances the
erosion of the soft rock it begins to
undercut the hard rock and as you can
see a section of it can drop off and
what we say is we say that the
waterfalls retreat upriver they retreat
backwards in fact Niagara Falls is
retreating somewhere about 50
centimeters each year now when the
undercut section drops off and falls
into the plunge pool the overhang drops
off that is it will break up into lots
of little rocks that will help of the
erosion and will enhance it
this is done through the process of
abrasion
as the waterfall retreats upstream it
forms a steep sided Gorge now you can
see over here in these photos that have
included air you can see the process at
the top and you can see an example of a
waterfall on the right-hand side I've
marked in the plunge pool and you can
see also the steep sided Gorge now this
would be quite a typical waterfall and
they can form thank you very much for
watching and have a great day
