Tectonic Plate Boundary

Tectonic plate boundary Separates plates

Tectonic plate bouldary is a fault line

A tectonic plate boundary is the fault line between crustal plates. There are divergent boundaries, convergent boundaries and transform boundaries.

Crustal plate boundaries are discovered using earthquake waves

Scientists use seismographs that record earthquake waves to find the outline of the different crustal plates. Numerous earthquakes occur along plate boundaries as the rocks break under the strain of the movement of the plates.

Tectonic plate boundaries, NASA

Pattern around crustal plates shows plate boundaries

Divergent boundaries

Separating plates create divergent boundaries

Divergent boundaries form when two plates are separating. A bulge forms along the boundary pushing up the seafloor.

A rift valley forms between the plates. Molten rock forms in magma chambers beneath the valleys. Fissures open up and lava pours out on the seafloor forming the newest crustal rocks on the planet.

Divergent boundaries found in all seafloors on Earth

Divergent boundaries are found on seafloors in all the oceans on Earth. The rift valleys are summit of a great mountain chain formed by the divergent boundaries called the global mid-ocean ridge. It is the largest volcanic feature on our planet and is approximately 80,000 km long.

Convergent boundaries

Two continental plates colliding create mountain chains

Convergent boundaries are places where two tectonic plates converge. A collision boundary forms when two continental crusts smash together. The crust is not destroyed. Instead, the extreme pressure as the tectonic plates converge create great mountain chains and deepen the crust beneath the mountain chain.

In the roots of the mountains minerals recrystallize

Metamorphic rocks form as minerals recrystallize in the rocks beneath the mountains due to the extreme heat and pressure. Gneiss rocks, which are high-grade metamorphic rocks, form at the base of the mountains where the pressure and heat is almost enough to cause the rocks to melt.


Heavier plate subducts in this zone

Subduction zones from when an oceanic plate converges with another tectonic plate. At the plate boundary an oceanic plate bends and is forced into the lithosphere. The rocks eventually melt and are recycled.

Volcanic mountains form above the melting plate

Above the melting seafloor on the overriding plate a chain of volcanic mountains grow. Between the two plates a trench forms. Off Guam in the Pacific Ocean is the Marianas Trench. The Challenger Deep is part of the trench and is the deepest point on Earth.

More Planet Earth Links

Plate Movements  Do you know what are divergent plate boundaries, convergent boundaries and transform faults. Find out on this page.

Crustal Plates  Find out how continental crust and oceanic crust forms on our planet.

The Earths Mantle  Find out about the Earths mantle that contains 84% of the Earth's mass.

Earths Interior  Find out about layers that have formed inside out planet and how they were discovered.

Alaska Northern Lights  Learn how and why the Northern Lights light up the sky in the Northern Hemisphere.

Tectonic Plate Boundary  Find out how and where a tectonic plate boundary forms on our planet.

Planet Earth  Find out about the different layers that make up planet earth from the core to outer space.

Home Page  The Science Site contains information on our planet, volcanoes, science activities, earthquakes and much more.


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