Chapter 6 Vocabulary

A solid sphere of metal, mainly nickel and iron, at Earth’s center.

• Inner Core

• Outer Core

A layer of molten metal, mainly nickel and iron, that surrounds Earth’s inner core.

• Inner Core

• Outer Core

The layer of rock between Earth’s outer core and crust, in which most rock is hot enough to flow in convection currents; Earth’s thickest layer.

• Mantle

• Crust

A thin outer layer of rock above a planet’s mantle, including all dry land and ocean basins.

• Mantle

• Crust

The layer of Earth made up of the crust and the rigid rock of the upper mantle, averaging about 40 kilometers thick and broken into tectonic plates.

• Lithosphere

• Asthenosphere

The layer in Earth’s upper mantle and directly under the lithosphere in which rock is soft and weak because it is close to melting.

• Lithosphere

• Asthenosphere

One of the large, moving pieces into which Earth’s lithosphere is broken and which commonly carries both oceanic and continental crust.

• Tectonic Plate

• Continental Drift

The hypothesis that Earth’s continents move on Earth’s surface.

• Tectonic Plate

• Continental Drift

A hypothetical supercontinent that included all of the landmasses on Earth. It began breaking apart about 200 million years ago.

• Pangaea

• Continental Drift

A long line of sea-floor mountains where new ocean crust is formed by volcanic activity along a divergent boundary.

• Mid-Ocean Ridge

• Pangaea