Valley facts for kids
A valley is a long, low area of land. It usually lies between hills or mountains. Often, a river or stream flows through it. Most valleys are shaped by erosion, which is when water or ice slowly wears away the land. This process takes a very long time.
Some valleys are carved by huge sheets of ice called glaciers. These icy valleys can still have glaciers in very cold places. Other valleys were formed by glaciers long ago, during ice ages. Now, these valleys are free of ice and have rivers instead. In deserts, valleys might be completely dry. Sometimes, water only flows through them after heavy rain. Rift valleys are different; they form when the Earth's crust moves and pulls apart. Scientists have many names for the different kinds of valleys we see around the world.
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How Valleys Are Formed
Valleys are dips in the land that usually slope downwards. They are often much longer than they are wide. Valleys can form in a few ways. The most common way is through erosion by moving water, like rivers. These are called river valleys. Water slowly wears away the land through processes like rubbing, grinding, and dissolving rocks.
Small streams often flow into bigger streams, which then join larger rivers. These rivers eventually reach the ocean. In very cold places or high mountains, glaciers can carve valleys. These valleys often look like a giant "U" shape. River valleys, however, usually have a "V" shape. Some valleys form from Earth's movements, like when the land splits apart. All these processes work together over millions of years to create valleys. The flat part at the bottom of a valley is called the valley floor. It's often made of sand and mud carried by the river.
River Valleys: Carved by Water
How a river valley forms depends on the type of rock and the climate. Rivers usually flow faster and erode more in their upper parts. Here, they cut deep into the land, creating steep, V-shaped valleys. Harder rocks or cracks in the Earth can make the river twist and turn.
Further downstream, many small streams join together. The valley becomes wider, and the river flows slower. Here, the river both erodes the land and drops off sediment. It erodes the outer bends of its path and deposits sand and mud on the inner bends. This creates the winding curves we call meanders. In the lowest part of a river, the land is very flat. The river forms wide meanders and a large floodplain. Here, the river mostly deposits sediment.
Sometimes, a river cuts so deeply that it forms a gorge, ravine, or canyon. This can happen if the land rises up, or if the sea level drops. When a river cuts deeper, it can also create flat steps along its sides, called river terraces.
Glacial Valleys: Shaped by Ice
Glacial valleys are carved by giant sheets of ice called glaciers. These valleys often have a special U-shape. They are common in mountains where glaciers once existed or still do. The glacier's movement grinds away the rock, making the valley wide and deep with steep sides and a flat bottom.
At the very top of a glacial valley, you might find bowl-shaped hollows called cirques. This is where glaciers first form. During past ice ages, like the Pleistocene period, glaciers grew from these cirques. They then flowed downhill, widening and deepening any existing river valleys. The ice carries rocks and debris, which act like sandpaper, carving the land.
When glaciers melt, they leave behind these U-shaped valleys. Sometimes, a small river flows through a huge glacial valley. This is called a misfit stream. Glacial valleys can also have steps or basins. If these basins fill with water, they become long, narrow lakes called ribbon lakes. When glacial valleys reach the sea, they can form deep, narrow inlets called fjords.
Famous examples of glacial valleys include Yosemite Valley in the United States.
Tunnel Valleys: Under the Ice
Tunnel valleys are huge, long, U-shaped valleys. They were carved by water flowing under massive ice sheets. These ice sheets once covered large parts of the Earth. Today, you can find them under the ice in Antarctica. Tunnel valleys can be up to 100 kilometers (62 miles) long and 400 meters (1,300 feet) deep. They acted like hidden rivers, carrying away huge amounts of meltwater from beneath the ice.
Meltwater Valleys: Rivers from Ice
In places like northern Europe, during past ice ages, huge ice sheets melted. The water from this melting ice created very wide, flat valleys. These are known as Urstromtäler. Unlike other glacial valleys carved by ice, these were formed by the powerful rivers of meltwater flowing away from the glaciers.
Hanging Valleys: Where Waterfalls Begin
A hanging valley is a smaller valley that sits higher than a main valley. This often happens in U-shaped valleys. A smaller glacier flows into a much larger one. The big glacier carves a very deep valley. The smaller glacier carves a shallower valley. When the glaciers melt, the smaller valley looks like it's "hanging" above the main one. Often, beautiful waterfalls tumble from these hanging valleys.
Hanging valleys can also form when different types of rock erode at different speeds. If a tributary valley has harder rock, it erodes slower than the main valley. This makes the tributary valley appear to hang above the main one.
Box Valleys: Flat Bottoms and Steep Sides
Box valleys have wide, flat floors and very steep sides. They are common in cold areas and also in deserts or tropical regions.
Rift Valleys: Earth's Cracks
Rift valleys, like the Great Rift Valley in Africa, are formed differently. They are created when the Earth's crust stretches and pulls apart. This happens because of huge movements deep inside the Earth.
Different Names for Valleys
People use many different words for valleys, depending on their shape or where they are. Here are a few:
- Arroyo: A dry riverbed that only fills with water after heavy rain.
- Canyon or gorge: A very deep, narrow valley with steep cliffs, often carved by a river.
- Dell: A small, quiet, and often wooded valley.
- Dry valley: A valley that doesn't have a permanent river flowing through it.
- Glen: A long valley with gently sloping sides, common in Scotland.
- Gulch: A deep, V-shaped valley formed by erosion.
- Hollow: A regional term for a small valley surrounded by hills.
- Ravine: A narrow valley, often smaller than a canyon, formed by stream erosion.
- Vale: A wide, open valley, often with a flat bottom.
- Wadi: A river valley in dry regions that only has water during heavy rains.
Valleys in the UK: Local Names
In places like Scotland, you might hear words like glen for a steep, narrow river valley, or strath for a wide, flat valley. In northern England, dale is a common word for a wide valley. The word combe is used in southern England for a short valley in a hillside. These local names show how different cultures describe their landscapes.
Valleys and Human Life
Many of the first human civilizations began in river valleys. Think of the Nile Valley in Egypt or the Tigris and Euphrates valleys. Rivers provided fresh water, food like fish, and a way to travel. The water also helped keep temperatures mild. This encouraged farming and the growth of early societies. People chose to live in valleys for these reasons, but they also learned to build homes away from areas that might flood.
Amazing Valleys Around the World
Here are some famous and interesting valleys from different parts of the world:
Africa
- Albertine Rift
- Great Rift Valley
- Nile Valley (Egypt/Sudan)
- Valley of the Kings (Egypt)
Asia
- Beqaa Valley (Lebanon)
- Jordan Valley (Jordan - Israel)
- Kathmandu (Nepal)
- Panjshir Valley (Afghanistan)
- Jiuzhaigou Valley (China)
Oceania
- Barossa Valley (Australia)
- Cagayan Valley (Philippines)
- Hunter Valley (Australia)
- Hutt Valley (New Zealand)
Europe
- Danube Valley (Eastern Europe)
- Glen Coe (Scotland, United Kingdom)
- Lauterbrunnen Valley (Switzerland)
- Loire Valley (France)
- Po Valley, (Italy)
- Rhone Valley (France)
- South Wales Valleys (United Kingdom)
North America
- Central Valley (California)
- Death Valley (California)
- Grand Canyon (Arizona, United States)
- Hudson Valley (New York)
- Las Vegas Valley (Nevada)
- Monument Valley (Arizona, Utah)
- Yosemite Valley (California)
South America
- Aburra Valley (Colombia)
- Calchaquí Valleys (Argentina)
- Paraíba Valley (Brazil)
Antarctica
- West Antarctic Rift System
Valleys Beyond Earth
Scientists have found many long, low areas on other planets and moons. These are called valles (singular: vallis). Deeper, steeper valleys are called chasmata. These names come from Latin words for 'valley' or 'gorge'. Studying these helps us understand how other planets formed.
See also
In Spanish: Valle para niños
