June exam: Tectonic Plates

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Continental drift hypothesis.

The Continental Drift Hypothesis was proposed by Alfred Wegener in 1912. The hypothesis proposed that the continents were once joined together in a single landmass called Pangaea, which later broke apart and drifted to their current positions.

How was the continental drift hypothesis supported?

The hypothesis was supported by several pieces of evidence, including the fit of the continents, the distribution of fossils, the distribution of rock types, and the distribution of ancient climates. However, the hypothesis was initially rejected by the scientific community because Wegener could not explain how the continents moved. It was not until the discovery of plate tectonics in the 1960s that the hypothesis was finally accepted.

What are key ocean floor formations?

continental shelf, continental slope, continental rise, abyssal plain, seamounts, mid-ocean ridges, and trenches.

What is the continental shelf?

A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea.

What is contiental slope?

The continental slope is the transition zone between the continental shelf and the deep ocean floor

What is the contienetal rise?

A continental rise is a gently inclined slope located between the base of the continental slope and the deep ocean floor

What is the abyssal plain?

An abyssal plain is a vast, flat, and sediment-covered area on the deep ocean floor

What are seamounts?

Seamounts are underwater mountains, typically volcanic in origin, that rise at least 1,000 meters (3,300 feet) from the seafloor and do not reach the surface

What are mid ocean ridges?

Mid-ocean ridges are underwater mountain ranges that run along the ocean floor and are formed by volcanic activity.

What are trenches?

Trenches are long, narrow, and deep depressions (ditches) in the ocean floor that are formed where tectonic plates collide.

What is seafloor spreading?

Seafloor spreading is the process by which new oceanic crust is formed at mid-ocean ridges and then spreads outward, carrying the continents with it.

How are new crusts formed?

New crust is formed at mid-ocean ridges through volcanic activity. Magma rises from the mantle and solidifies to form a new crust. As new crust is formed, older crust is pushed away from the ridge and moves outward. This process creates a conveyor belt-like system where the oceanic crust is constantly being created, destroyed, and recycled.

How did seafloor spreading and new crusts being formed support the continental drift hypothesis?

Seafloor spreading supported the Continental Drift Hypothesis because it provided a mechanism for how the continents could move. If a new crust was being created at mid-ocean ridges, then the continents could be carried along with it. Seafloor spreading also explained why the oceanic crust was much younger than the continental crust. If a new crust was being formed at the ridges, then the oceanic crust would be much younger than the continental crust, which had been around for billions of years.

What are plate tectonics?

Plate tectonics is the scientific theory that explains how the Earth's lithosphere is divided into several large, rigid plates that move relative to one another.

What is the lithosphere

The lithosphere is the outermost layer of the Earth, consisting of the crust and the upper part of the mantle. It is relatively rigid and brittle and is broken up into several large plates.

What is the asthenosphere?

The asthenosphere is a layer of the Earth's mantle that lies beneath the lithosphere. It is partially molten and has a plastic-like consistency. The asthenosphere is the layer upon which the lithospheric plates move and it is thought to be the source of the convection currents that drive plate tectonics.

What are the three different types of plate boundaries?

Divergent, convergent, transform.

What are divergent boundaries?

Divergent boundaries occur where two plates move away from each other. This type of boundary forms mid-ocean ridges, where new oceanic crust is formed as magma rises from the mantle and solidifies.

What are convergent boundaries?

Convergent boundaries occur where two plates move toward each other. This type of boundary forms subduction zones, where one plate is forced beneath the other and into the mantle. This process can lead to the formation of mountains, volcanic activity, and earthquakes.

What are transform boundaries?

Transform boundaries occur where two plates slide past each other horizontally. This type of boundary forms strike-slip faults, where the plates move in opposite directions and can cause earthquakes.

What is mantle convection?

Mantle convection is the process by which heat from the Earth's core causes the mantle to circulate and move. This circulation of the mantle is driven by convection currents, which are caused by differences in temperature and density.

As the mantle circulates, it moves the lithospheric plates that rest on top of it. This movement of the plates is known as plate tectonics. Plate tectonics is responsible for the formation of many geological features, such as mountains, oceanic trenches, and volcanic islands.

How can mantle convection be modelled?

using numerical simulations, which involve solving the equations of conservation of mass, momentum, and energy, along with a simplified rheology and equation of state

What causes the formation of earthquakes?

Earthquakes occur when two lithospheric plates move past each other along a fault. The sudden movement releases energy, which causes seismic waves to propagate through the Earth.

What causes the formation of volcanoes?

Volcanoes occur when magma from the mantle or the asthenosphere rises to the surface. This can happen at divergent boundaries, where new oceanic crust is formed, or at convergent boundaries, where one plate is forced beneath another. When magma reaches the surface, it can erupt as lava, ash, and other volcanic materials. Usually occur in hotter areas

What causes the formation of islands?

Islands form through various geological processes, primarily volcanic activity, tectonic plate movements, and sedimentation. Volcanic eruptions build up layers of lava, eventually creating islands above sea level. Tectonic plate movements can cause land to rise above water or separate from a continent, forming continental islands. Sedimentation from rivers and waves can also contribute to island formation, creating barrier islands and other landforms