Lecture 3 - The Mobile Crust: Key Terms (VOCABULARY)

15 vocabulary flashcards covering key terms from the lecture on plate tectonics and seafloor geology.

Plate tectonics

The theory that Earth's lithosphere is broken into moving plates that interact at their boundaries.

Lithosphere

The rigid outer shell of the Earth, consisting of the crust and upper mantle.

Asthenosphere

The partially molten, ductile layer beneath the lithosphere that allows plates to move.

Mesosphere

The lower mantle; a solid, more rigid layer beneath the asthenosphere.

Crust

The Earth's outer silicate layer; it is thin compared to the mantle and core.

Mantle

The silicate layer between the crust and core that makes up most of Earth's volume.

Core

Earth's center, with a liquid outer core and a solid inner core; source of the magnetic field.

Mid-ocean ridge

An underwater mountain range where seafloor spreading and volcanism occur at the ridge axis.

Seafloor spreading

The process by which new oceanic crust forms at mid-ocean ridges and moves outward.

Subduction

The process by which one plate sinks beneath another into the mantle at a boundary.

Pangaea

The ancient supercontinent that split into Laurasia and Gondwanaland; proposed by Wegener.

Magnetite

An iron oxide mineral (Fe3O4) in basalt that aligns with Earth's magnetic field as it cools.

Curie temperature

The temperature (about 570°C) at which magnetite grains lock in their magnetic orientation.

Magnetic stripes

Parallel bands of normal and reversed polarity in seafloor basalts that record magnetic reversals.

Magnetic reversals

Periodic flips in Earth's magnetic field polarity over geological time.