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The feature that forms where plates move away from each other in the middle of the ocean is called a mid-ocean ridge. This is a long, undersea mountain range formed by the upwelling of magma from the mantle as tectonic plates diverge.
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When an oceanic plate collides with a continental plate, the denser oceanic plate is typically subducted beneath the lighter continental plate. This subduction process can lead to the formation of a trench at the point of collision, as well as volcanic activity and mountain building on the continental plate due to the melting of the subducted oceanic plate.
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New material is added to the ocean floor at mid-ocean ridges where tectonic plates are pulling apart. Magma rises from the mantle to fill the gap, solidifying and forming new oceanic crust. Simultaneously, older material is reabsorbed at subduction zones, where one plate dives beneath another, often resulting in increased geological activity such as earthquakes and volcanic eruptions.
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Scientists have several pieces of evidence to show that the continents have moved over time, including:
- Fossil evidence: Similar fossils of plants and animals are found on continents that are now separated by vast oceans, suggesting they were once connected.
- Geological evidence: Rock formations and mountain ranges that align across continents indicate that they were once part of the same landmass.
- Paleoclimatic evidence: The distribution of ancient climate indicators, such as coal deposits in formerly tropical regions now in colder climates, suggests continental movement.
- Fit of the continents: The shapes of continents, such as the east coast of South America and the west coast of Africa, appear to fit together like puzzle pieces, supporting the idea of continental drift.
- Plate tectonics: The study of tectonic plates and their movements provides a mechanism for the movement of continents over geological time.
1
Name the feature that forms where plates move away from each other in the middle of the ocean.
2
Describe what happens to an oceanic plate when it collides with a continental plate.
3
Describe how new material is added to the ocean floor while older material is reabsorbed.
4
What evidence do scientists have to show that the continents have moved over time?
1 answer