Canyons 101

We all have heard of canyons, many people have visited them and know them as dramatic and stunning landscapes. 

What are canyons? 

Canyons, sometimes called gorges, are deep, narrow valleys with steep sides. These landscapes can be created by the breakdown of rocks, erosion, the movement of tectonic plates and by flowing rivers. 

There are several types of canyons

1. River canyons: These are canyons that are formed over time by the pressure of a river cutting through the river bed and creating a channel over time. These rivers are known as entrenched rivers because they don’t meander or change course, but are confined to the channel they create. The Grand Canyon is a river canyon created by the Colorado River.
2. Slot canyons: These are in soft rocks like sandstone. In the winter, water seeps into cracks in the rock and then freezes. When it turns into ice it expands and erodes the cracks in the rock, making them larger. During rainstorms rushing water will cause these cracks to erode further and widen the canyon. This results in deep and narrow canyons with smooth walls. One of largest slot canyons in the world is Utah’s Buckskin Gulch.
3. Box canyons: These canyons are made of hard rocks like limestone and may be formed by springs at the base of cliffs. When the ceiling of the caves collapses, box canyons are formed and typically have an opening on one end. Box canyons have been used historically by the Hopi and Navajo people as corrals for sheep and cattle. Many of the side canyons in Grand Canyon National Park are considered to be box canyons.
4. Submarine canyons: These are underwater canyons, with steep slopes that cut into continental shelves. Some submarine canyons are formed by rivers that flowed along these shelves during earlier periods. Others are formed when canyons are formed on the ocean floor by ocean currents sweeping away sediments and debris. Submarine canyons are extremely rich in biodiversity, but little is known about them because they can be so deep and difficult to explore. Monterey Canyon in California is one of the most frequently studied submarine canyons.

Why are canyons important? 

1. Fostering unique conditions for biodiversity: Canyons have different environmental conditions from the surrounding area that can affect which plants and animals live and thrive. These conditions include things like temperature, moisture, climate and light. Plants and animals behave differently and some species may survive better than others in canyons. Canyon walls can block the movement of animals. Canyons form corridors and species can be moved through them on the river that flows through and can move the opposite direction during flooding. And caves and springs will provide stable conditions that allow species to thrive that only exist in specific conditions. In the Grand Canyon, 70% of larger lifeforms are restricted by the canyon.
2. Predicting future changes: Geologists are able to study exposed layers of rocks in a canyon and geological formations to understand water flow rates, dry years, species composition, and climate change patterns. Experts can use this data to predict future changes to the landscape and surrounding area.
3. Learn about local history: Studying canyons can shed light on the earlier history of the landscape. Many indigenous communities have lived on and around canyon ledges, such as the Hopi and Sinagua tribes. Dwellings for hundreds of people were made on the cliffs and throughout the canyon and local resources were used for subsistence.

Fun facts about canyons

• The largest canyon in the world is Yarlung Zangbo Grand Canyon in Tibet. The canyon reaches 5,300 meters from top to bottom, the equivalent of almost fifty football fields. 
• It is estimated that there are approximately 9,000 canyons across the planet.
• In 2013 the longest canyon in the world was discovered under an ice sheet in Greenland, spanning an impressive 470 miles long. 
• The Grand Canyon boasts over 1,000 caves, and only 335 of these caves have been explored. 
• One billion years worth of fossil life have been discovered in Arizona’s Grand Canyon, approximately 32% of Earth’s geological history.