Eighty kilometres of steep walled canyons, composed of sedimentary and volcanic rock, has been carved by eons of river erosion, resulting in the Grand Canyon.
(Eighty kilometres of steep walled canyons; composed; of sedimentary and volcanic rock) (Eighty kilometres of steep walled canyons, composed of sedimentary and volcanic rock; has been carved; by eons of river erosion)
Eighty kilometres of steep walled canyons Eighty kilometres of steep walled canyons, composed of sedimentary and volcanic rock
composed has been carved
of sedimentary and volcanic rock
by eons of river erosion