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Rift valley

earth science Maturity 11-13 Next article →

A rift valley is a long, low area of land. It sits between high lands or mountain ranges. These valleys form because of a geologic rift. This happens when the lithosphere pulls apart. The lithosphere is the outer layer of our Earth. As the ground stretches, the land sinks down. This creates a long, linear depression.

Browncanyonquilotoa
Browncanyonquilotoa

Over time, wind and water can make the valley deeper. This is called erosion. These valleys often fill up with sediment. Sediment is material that washes down from the sides. Many rift valleys also hold huge lakes.

How these valleys work can be quite complex. Sometimes, tectonic plates are actually breaking apart. This process can turn a continent into an ocean. Other rifts come from bends in faults. A fault is a crack in the Earth's crust. If a fault has a bend, the ground might stretch. This stretching causes the land to sink. This is called subsidence.

Small rifts can even make sag ponds. These are small pools of water. Larger rifts can change the whole shape of a landmass.

Scientists study many different types of rifts. The most extensive rift is on the sea floor. It follows the mid-ocean ridge system. This happens because of sea floor spreading. The Mid-Atlantic Ridge is a famous example. The East Pacific Rise is another one. On land, some rifts are still active today. The East African Rift is very well known. The Rio Grande rift is also active. The Baikal Rift Zone is a third active one.

NASA - Visible Earth, Lakes of the African Rift Valley
NASA - Visible Earth, Lakes of the African Rift Valley

There is also a fourth one in West Antarctica.

Many of the world's largest lakes live in rifts. Lake Baikal in Siberia is a World Heritage Site. It is the deepest lake on Earth. It holds 20% of all liquid freshwater on Earth. Lake Tanganyika is also very deep. It sits in the Albertine Rift. This is part of the East African Rift.

Thingvallavatn Lake
Thingvallavatn Lake

In North America, Lake Superior is very large. It sits in the ancient Midcontinent Rift. Other lakes like Lake Vostok might be in old rifts. Even in Canada, the Ottawa-Bonnechere Graben holds lakes.

We can find rift valleys in space, too. Mars has a giant system called Valles Marineris. It is 4,000 km long. On Venus, the Devana Chasma is 4,000 km long. Some moons also have these huge cracks. Tethys has the Ithaca Chasma, which is 2,000 km long. Charon has the Nostromo Chasma. Even the moon has ancient rift valleys. These include Vallis Rheita and Vallis Alpes. Looking at these rifts helps us understand other worlds.

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🖼️ Images & Media (4)
File:NASA - Visible Earth, Lakes of the African Rift Valley.jpg
NASA - Visible Earth, Lakes of the...
File:Browncanyonquilotoa.jpg
Browncanyonquilotoa.jpg
File:Ottawabonnecheregrabenmap.png
Ottawabonnecheregrabenmap.png
File:Thingvallavatn Lake.jpg
Thingvallavatn Lake.jpg
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