Tectonic plates p.1

Tectonic plates.

Earth is covered in a thin layer of solid rock called the crust. This is not a single, unbroken shell. but consists of sections called tectonic plates. These plates are not fixed, but move around slowly in relation to one another. The term "tectonic" means "to do with building" and the motion of the piates is what constructs large scale surface features, such as ocean trenches and mountain ranges.

Andes Mountains form along plate boundary

Boundary of major plates forms Mid-Atlantic Ridge

Near Easter Island, the rift between the Pacific plate and Nazca plate is spreading by 15 cm (6in) every year

Downward current drags crust Into mantle, where it melts

Surface plate drifts along with motion of upper mantle

How plates move. Beneath Earth's solid crust lies a deeper layer called the mantle (see pp.46-47). The heat from the planet's core keeps the rock in the mantle permanently fluid. The tectonic plates float on this fluid material and are moved by currents that flow slowly up, down, and through it.

Anatolian microplate creates frequent earthquakes

Plates of Earth. Most of Earth's surface is covered by Just seven major tectonic plates, although there are several dozen plates in total. The larger ones are labelled below. The others are so called microplates, which form unstable parts of the crust that are prone to earthquakes. Earthquakes are caused by sudden movements at plate boundaries.

Great Rift Valley forms as plates move apart

Sunda Trench forms where plates converge

INTERFEROMETRY. Plate movement can be tracked by interferometry. This uses radio waves emitted by a distant galaxy to measure precisely the slowiy changing distance between radio telescopes on different plates.

Upward mantle plume forces plates apart

Hot material rises from the lower mantle.

Convection currents. The motion of the mantle is driven bv convection currents (see p.185), which transfer heat from the core.

Tectonic plates. Earth is covered in a thin layer of solid rock called the crust. This is not a single, unbroken shell. but consists of sections called tectonic plates. These plates are not fixed, but move around slowly in relation to one another. The term "tectonic" means "to do with building" and the motion of the piates is what constructs large scale surface features, such as ocean trenches and mountain ranges.

Andes Mountains form along plate boundary

Boundary of major plates forms Mid-Atlantic Ridge

Near Easter Island, the rift between the Pacific plate and Nazca plate is spreading by 15 cm (6in) every year

Downward current drags crust Into mantle, where it melts

Surface plate drifts aong with motion of upper mantle

How plates move. Beneath Earth's solid crlies a deeper layer called the mantle (see pp.46-47). The heat from the planet's core keeps the rock in the mantle permanently fluid. The tectonic plates float on this fluid material and are moved by currents that flow slowly up, down, and through it.

Anatolian microplate creates frequent earthquakes

Plates of Earth.

Most of Earth's surface is covered by Just seven major tectonic plates, although there are several dozen plates in total. The larger ones are labelled below. The others are so called microplates, which form unstable parts of the crust that are prone to earthquakes. Earthquakes are caused by sudden movements at plate boundaries.

Great Rift Valley forms as plates move apart

Sunda Trench forms where plates converge

INTERFEROMETRY

Plate movement can be tracked by interferometry. This uses radio waves emitted by a distant galavy to measure precisely the slowiy changing distance between radio telescopes on different plates.

Upward mantle plume forces plates apart

Hot material rises from the lower mantle.

Convection currents. The motion of the mantle is driven bv convection currents (see p.185), which transfer heat from the core to nearer the surface.

Tectonic plates are sections of Earth's crust that move slowly in relation to one another, forming large-scale surface features like ocean trenches and mountain ranges. The term "tectonic" refers to building, highlighting how plate motion constructs the Earth's surface. The Andes Mountains form along plate boundaries, and near Easter Island, the rift between the Pacific plate and Nazca plate spreads about 15 cm (6 in) annually. Below the crust lies the mantle, where heat from the core keeps rock fluid, allowing tectonic plates to float and be driven by convection currents. Earthquakes occur at plate boundaries due to sudden movements, with the Great Rift Valley forming as plates diverge and the Sunda Trench forming where they converge. Plate movement can be monitored using interferometry, which measures changes in distance between radio telescopes on different plates. Most of Earth's surface consists of seven major tectonic plates, along with several dozen microplates, which are unstable and prone to earthquakes. Upward mantle plumes force plates apart as hot material rises from the lower mantle.