Canyons are deep cleft between cliffs that can be a result of erosion or weather. Over time, a river may erode through the sediments forming a deep gorge as it runs downstream. Very slowly, over years, the riverbed reaches the baseline elevation of the river bed. It is dependent on soft and hard rock layers how the canyon is shaped.
Canyons can also be spotted between two mountain peaks. Such ranges with canyons between them include the Himalayas, Andes, Alps, and the Rocky Mountains.
There are two main types of canyons: box and slot. Box canyons occur in mountainous regions, either within mountains or canyons that only open at one side. Narrow ones have very smooth walls and are referred to as the slot canyons. There are some canyons in the seabed as well that form from landslides and turbidity currents.
The word canyon comes from the Spanish word canon which means gorge. Most canyons form over really long periods of time and are more common in wet areas. The water from the river and wind is the primary cause of less resistant materials like shale chipping away. Frost wedging can also assist the process. This is when the water seeps into the ground and freezes causing rocks to dislodge and break free.
The largest canyon in terms of depth is the Yarlung Tsangpo Grand Canyon which has formed along the River Tibet. The Kali Gandaki Gorge in Nepal is also one of the deepest canyons in the world. However, one of the most famous and largest canyons of the world remains the Grand Canyon in the United States.
Canyons are actually the perfect places to study the history of the planet. The exposed layers of rock can show experts how climate has changed over time, as well as deduce some organisms that lived over the years. It can also highlight the future of the canyon through the rocks. For example, the oldest rocks from over 17 million years ago were discovered in the rock layer near Columbia River Gorge. They have been found to have formed from volcano eruptions millions of years ago.