12. Grand Canyon,
USA Interaction of all these
geomorphic and tectonic
processes created the current
canyon. The oldest deposits at
the bottom are 2 billion years
old, the youngest 230 million
years old at the rim. Most of
these deposits were laid down
when the canyon was actually
under a shallow ocean.
Uplifting began 65 million years
ago. A fall in sea level 5.3
million years ago caused the
river to cut down even faster
through the rock layers. This
increased rate of erosion had
Weathering Erosion Folding and
cut the canyon’s current depth
by 1.2 million years ago.
Landscapes are the product of
Deposition the complex interaction of a
range of processes over long
periods of time.