Bound by cliffs and cut by erosion, canyons are deep, narrow valleys in the Earth’s crust that evoke superlatives and a sense of wonder. Layers of rock outline stories of regional geology like the table of contents to a scientific text.
The landforms commonly break parched terrain where rivers are the major force that sculpts the land. They are also found on ocean floors where the currents dig underwater grooves.
“Grand” is the word used to describe one of the most famous canyons of all. Cut by the Colorado River over the last few million years, the Grand Canyon is 277 miles (446 kilometers) long, more than 5,000 feet (1,500 meters) deep, but only 18 miles (29 kilometers) across at its widest yawn.
Layers of rock in the Grand Canyon tell much about the Colorado Plateau’s formative years: a mountain range built with two-billion-year-old rock and then eroded away; sediments deposited from an ancient sea; more mountains; more erosion; another sea; a burst of volcanic activity; and the birth of a river that has since carved the chasm by washing the layers away.
Each layer erodes differently. Some crumble into slopes, others sheer cliffs. They stack together like a leaning staircase that leads to the river’s edge. A mixture of minerals gives each layer a distinctive hue of yellow, green, or red.
Credit : National Geographic
Picture Credit : Google
