Formation
Canyons are formed because of the fact that erosion
takes place causing the formation of features on the earth’s surface. In
the case of a canyon the erosive action takes place in the form of water
running through a dry region with sedimentary rock layers of varying resistance
Three basic processes take place:
·Removal
& transportation of eroded rock material:
This process is
very simple in the formation of a canyon, although very important. This
is where water in the form of a fast flowing river washes this weathered
rock material is transported downstream as sediment load into the surrounding
drainage basins
·Downcutting
of stream channels through vertical erosion:
Downcutting is a
process which occurs in all stream channels due to erosion, especially
that of abrasion[the process of erosion where sand and gravel from
the river load rub against the floor and banks of a river ] This action
results in the carving of formations such as
potholes.
With downcutting, the migration of waterfalls further upstream occurs through
undermining as well.
·Headward
erosion:
This process is
due to a natural tendency of a river to erode headward/upstream. This is
also known as slope retreat
These three basic
processes result in the formation of a canyon. This transition from a flat
piece of land to a mighty canyon may take tens of millions of years to
reach a significant magnitude and even then the evolution of a canyon will
never stop unless one of the elements of formation is removed
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