Explanation:

Explanation:
1. A gorge is a narrow valley with steep, rocky walls located between hills or mountains. The term  comes from the French word gorge, which means throat or neck. A gorge is often smaller than  a canyon, although both words are used to describe deep, narrow valleys with a stream or river  running along their bottom. A number of natural forces form gorges. The most common  is erosion due to streams or rivers. Streams carve through hard layers of rock, breaking down or  eroding it. Sediment from the worn-away rock is then carried downstream. Over time, this erosion  will form the steep walls of a gorge. The flooding of streams or rivers increases the speed and  intensity of this erosion, creating deeper and wider gorges. The deep Talari Gorges in Mali, for  instance, were formed by the Sngal River that flows into the Atlantic Ocean on the western coast  of Africa. Geologic uplift also forms gorges. Geologic uplift is the upward movement of the Earth’s surface. Geologic uplift is often associated with earthquakes and orogeny, the process of creating  mountains. During  geologic uplift, rock layers beneath the Earth’s surface bump against the  surface layers. Softer layers of surface rock erode.Erosion and geologic uplift often work together  to create gorges. Parts of streams or rivers can be elevated, along with land, during the process of  geologic uplift. As rivers or streams flow across this uplifted surface, waterfalls form. Over time,  the power of the waterfall erodes the softer rock layers underneath, causing the original river  bed to collapse and create a gorge. Macocha Gorge in the Jihomoravsk region of the Czech  Republic was probably formed by the collapse of an underground cave that had been eroded by  the Punkva River. The movement and melting of glaciers can also produce gorges. Glaciers cut  deep valleys into the Earths surface. These rivers of ice can create huge canyons and sharp,  steep gorges. As glaciers melt, or retreat, these gorges and canyons are exposed. The Columbia  River Gorge, located in the U.S. states of Washington and Oregon, was partially created by glacial  retreat during the last Ice Age.

2. A canyon is a deep, narrow valley with steep sides. “Canyon” comes from the Spanish word cañon, which means “tube” or “pipe.” The term “gorge” is often used to mean “canyon,” but a  gorge is almost always steeper and narrower than a canyon. The movement of rivers, the processes of weathering and erosion, and tectonic activity create canyons.
A. River Canyons: The most familiar type of canyon is probably the river canyon. The water  pressure of a river can cut deep into a river bed. Sediments from the river bed are  carried downstream, creating a deep, narrow channel. Rivers that lie at the bottom of deep  canyons are known as entrenched rivers. They are entrenched because, unlike rivers in wide,  flat flood plains, they do not meander and change their course. The Yarlung Zangbo Grand  Canyon in Tibet, a region of southwestern China, was formed over millions of years by the Yarlung Zangbo River. This canyon is the deepest in the world—at some points extending more than 5,300  meters (17,490 feet) from top to bottom. Yarlung Zangbo Canyon is also one of the world’s longest  canyons, at about 500 kilometers (310 miles).
B. Weathering and Erosion: Weathering and erosion also contribute to the formation of canyons.  In winter, water seeps into cracks in the rock. This water freezes. As water freezes, it expands and  turns into ice. Ice forces the cracks to become larger and larger, eroding bits of stone in the  process. During brief, heavy rains, water rushes down the cracks, eroding even more rocks and  stone. As more rocks crumble and fall, the canyon grows wider at the top than at the bottom. When this process happens in soft rock, such as sandstone, it can lead to the development of slot  canyons. Slot canyons are very narrow and deep. Sometimes, a slot canyon can be less than a  meter (3 feet) wide, but hundreds of meters deep. Slot canyons can be dangerous. Their sides are  usually very smooth and difficult to climb. Some canyons with hard, underlying rock may develop  cliffs and ledges after their softer, surface rock erodes. These ledges look like giant steps. Sometimes, entire civilizations can develop on and around these canyon ledges. Native American  nations, such as the Hopi and Sinagua, made cliff dwellings. Cliff dwellings were apartment-style  shelters that housed hundreds of people. The shaded, elevated ledges in Walnut Canyon and  Canyon de Chelly, in Arizona, provided protection from hostile neighbors and the  burning desert sun. Hard-rock canyons that are open at one end are called box canyons. The Hopi  and Navajo people often used box canyons as natural corrals for sheep and cattle. Theysimply built a gate on the open side of the box canyon, and closed it when the animals were inside. Limestone is a type of hard rock often found in canyons. Sometimes, limestone erodes and forms  caves beneath the earth. As the ceilings of these caves collapse, canyons form. The  Yorkshire Dales, an area in northern England, is a collection of river valleys and canyons created  by limestone cave collapses.
C. Tectonic Uplift: Canyons are also formed by tectonic activity. As tectonic plates beneath the  Earth’s crust shift and collide, their movement can change the area’s landscape. Sometimes,  tectonic activity causes an area of the Earth’s crust to rise higher than the surrounding land. This  process is called tectonic uplift. Tectonic uplift can create plateaus and mountains. Rivers  and glaciers that cut through these elevated areas of land create deep canyons. The Grand  Canyon, in the U.S. state of Arizona, is a product of tectonic uplift. The Grand Canyon, up to 447  kilometers (277 miles) long, 29 kilometers (18 miles) wide, and 1.8 kilometers (6,000 feet) deep, is  the largest canyon in the United States. The Grand Canyon has been carved, over millions of  years, as the Colorado River cuts through the Colorado Plateau. The Colorado Plateau is a large  area that was elevated through tectonic uplift millions of years ago. Geologists debate the age of  the canyon itself—it may be between 5 million and 70 million years old.