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Landforms Grade 4
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Landform Grade 4
Rumana Fariha
What is land form?
A land form is a feature on the Earth's surface that is part of the terrain. Mountains, hills, plateaus, and plains are the four major types of landforms. Minor landforms include canyons, valleys, and basins.
Mountains
Mountains are landforms higher than the surrounding areas. They are formed due to the tectonic movements, earthquakes, volcanic eruptions and erosion of the surrounding areas caused due to wind, water and ice. Mountains are found in the oceans and on land.
picture of mountain
picture of mountain
types of Mountains
- Fold Mountains (Folded Mountains)
- Fault-block Mountains (Block Mountains)
- Dome Mountains.
- Volcanic Mountains.
- Plateau Mountains.
Examples of mountains
Examples of mountains
- Mount Everest, Himalayas, Nepal/Tibet Autonomous Region, China – 8848 m
- K2, Karakorum, Pakistan/China – 8611 m.
- Kanchenjunga, Himalayas, Nepal/India – 8586 m.
- Lhotse, Himalayas, Nepal/Tibet Autonomous Region, China – 8516 m.
Where Do Mountains Come From?
Plateaus
Plateaus are flat highlands that are separated from the surroundings due to steep slopes. They are formed by collisions of tectonic plates, magma action that causes the elevation in earth’s crust.
Picture of plateau
The Largest one
The biggest, tallest plateau in the world is the Tibetan Plateau. The Tibet Autonomous Region (TAR), is a province-level autonomous region of the People's Republic of China (PRC). Its capital is Lhasa. English speakers often call this region Tibet, but Tibet can also mean any place where the Tibetan culture is local to.
Map of Tibet in Yellow
A short documentary
Where in the world
The largest plateaus include the continent of Africa, the western plateau of Australia, and the Arabian Peninsula. In North America, plateaus occur along the western mountain system, in Alaska, and west of the Appalachian Highlands. South America has plateaus in five regions: Guiana Highlands, Brazilian Highlands, Paraná Basin, Patagonia region, and the Andes. In Europe, plateaus are found in Spain, north of the Alps, in Scandinavia, and in western Russia. There are spectacular plateaus in central Turkey, Iran, Central Asia, and the extensive region covered by the Tibetan Plateau.
Formation
Many plateaus form as magma deep inside the Earth pushes toward the surface but fails to break through the crust. Instead, the magma lifts up the large, flat, impenetrable rock above it.
Repeated lava flows that spill out from cracks in the ground and spread out over hundreds of square miles can also slowly build up massive plateaus.
Valleys
Valleys are low-lying areas of land between hills and mountains that are formed due to the actions of glaciers and rivers over millions of years. Depending on the shape they are classified as V shaped valleys and U shaped valleys. V-shaped valleys are formed by the flowing rivers and U-shaped valleys are formed due to glaciers.
Pictures of valleys
river valley
Like other landforms, river valleys are always changing. Rivers continually wear away the land through which they flow, gradually making the valleys deeper. At the same time, other forces loosen material on the valley walls. These forces include rain, frost, and wind. The eroded material from the valley walls falls into the river and is carried away.
Some river valleys
Glacial Valleys
Not all valleys are formed by rivers. Some valleys are formed by huge, slowly moving bodies of ice called glaciers. Thousands of years ago glaciers covered large parts of Earth’s surface. As the glaciers moved along, they scraped the land and carried away giant boulders and huge amounts of soil. They left valleys behind.
A short video
Deserts
Due to lack of adequate rainfall, desert is a dry piece of land with little or no vegetation. They are mostly found mainly in rain shadow areas which are leeward of a mountain range with respect to the wind direction. In deserts, the atmospheric air is very dry, and daytime temperature is high.
Pictures of deserts
facts on deserts
Most of our deserts are located in subtropical regions around the Tropics of Cancer and the Tropic of Capricorn as well as in the polar regions
Deserts are also called arid areas. Arid comes from the Latin word aridus and means dry, actually so dry that only few plants can grow on it.
facts on deserts
There are hot deserts such as the Sahara Desert and cold deserts such as the Gobi Desert or the deserts of our polar regions.
Big differences in daily temperatures are experienced in the deserts. The temperature during the sunshine hours are usually very high while night temperatures are cold as the heat can quickly escape.
A short video
Islands
An island is a piece of land which is surrounded by water from all sides and formed either due to volcanic eruptions or due to hot spots in the earth.
Pictures of islands
Facts about Islands
- Java is the world's most populated island with over 130 million people.
- Some islands are man made. One example of this is the Kansai Airport in Japan which sits on a man made island.
- The largest island in the Mediterranean Sea is Sicily.
Facts about Islands
Oceanic Islands
Oceanic islands are the tops of underwater volcanoes. An oceanic island forms when a volcano erupts deep under the ocean and pushes the ocean floor upward into a mountain. The island is the top of that mountain. The Hawaiian Islands are examples of oceanic islands.
Continental islands
Continental islands are close to the continents. They are parts of the same land that makes up the continents. One way that continental islands form is by the flooding of valleys close to the coast. The valleys fill with seawater, and the tops of nearby hills then become islands. Long Island, which lies off the coast of New York State, is a continental island.
Continental islands
Continental Islands
The islands in rivers and lakes are also continental islands. The city of Paris, France, began as a settlement on an island in the Seine River.
Archipelago
An archipelago is a group of islands. The islands in archipelagos may be oceanic or continental. Japan and the Aleutian Islands in Alaska are archipelagos. Indonesia is the largest archipelago in the world.
Short video
Plains
Plains are flat or the low relief areas on the surface of the earth. It might be formed as a result of the sedimentation of eroded soil from the top of the hills and mountains or might be due to flowing lava deposited by the agents of wind, water, and ice.
Pictures of plains
Types of plains
Based on their mode of formation, plains of the world can be grouped into 3 major types:
- Structural plains
- Depositional plains
- Erosional plains
Structural plains
These are formed by the horizontally bedded rocks, relatively undisturbed by the crustal movements of the earth. examples are -
- Russian platform
- Great Plains of USA
- Central lowlands of Australia
Depositional Plains
These plains are formed by the deposition of materials brought by various agents of transportation like glaciers, rivers and wind. River plains like - Ganga delta (Bangladesh) is the most significant.
Erosional plain
These plains are carved by the agents of erosion. Rains, rivers, ice and wind help to smooth out irregularities in earth's surface and convert them to low plains.
Great plains
Canyon
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.
Pictures of canyon
features of canyon
Canyon, deep, steep-walled, V-shaped valley cut by a river through resistant rock. Such valleys often occur in the upper courses of rivers, where the stream has a strong, swift current that digs its valley relatively rapidly. Smaller valleys of similar appearance are called gorges.
What is the largest canyon in the world?
The Grand Canyon
The Grand Canyon, Grand Canyon National Park, Arizona, US
The Grand Canyon runs 277 miles long, up to 6,000 feet deep, and 18 miles wide. It's the largest (longest) canyon in the world
Short video on the Grand Canyon
Valley vs Canyon
The main difference between Valley and Canyon is that the Valley is a low area between hills, often with a river running through it and Canyon is a deep ravine between cliffs. A valley is a low area between hills or mountains often with a river running through it.