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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