Plate Tectonics and Earth Structure

Vocabulary flashcards covering Earth's internal layers, plate tectonic boundaries, continental drift evidence, and global seismic activity based on lecture notes.

Crust

The Earth's outer layer, ranging from $0\text{ to }100\,km$ thick, composed of silicate rocks such as Basalt and Granite.

Lithosphere

The brittle, rigid outer shell of the Earth consisting of the crust and uppermost solid mantle.

Asthenosphere

The plastic, flowing layer of the mantle located directly beneath the lithosphere.

Mesosphere

The solid lower mantle layer of the Earth.

Mantle

The layer of the Earth composed of semi-solid Iron and Magnesium.

Core

The dense center of the Earth composed of Iron and Nickel, consisting of a liquid outer core extending to $5100\,km$ and a solid inner core extending to $6378\,km$.

Continental Drift

The theory proposed by Alfred Wegener in $1912$ stating that continents fit together like puzzle pieces and have moved over time.

Mesosaurus

A fossilized species found in both Africa and South America that serves as fossil evidence for Continental Drift.

Convection Currents

Circular mantle movements powered by radioactive decay in Earth's core, where hot, less dense rock rises and cooler, denser rock sinks to drag tectonic plates above.

Divergent Boundary

A boundary where tectonic plates move apart and magma rises to create new crust, such as at the Mid-Atlantic Ridge or rift valleys.

Convergent Boundary

A boundary where tectonic plates move together, resulting in subduction or mountain building, as seen in the Himalayas or Andes Mountains.

Transform Boundary

A boundary where tectonic plates slide past each other, causing pressure to build and release as earthquakes, such as along the San Andreas Fault.

Subduction Zone

A region where a denser oceanic plate dives under a continental plate, melting rock and generating violent volcanoes and deep ocean trenches like the Mariana Trench.

Ring of Fire

A major seismic area accounting for nearly $90\%$ of the world's earthquakes and $75\%$ of active volcanoes.

Rodinia

A supercontinent that formed $1\text{ billion}$ years ago.

Pangea

A supercontinent that assembled $300\text{ million}$ years ago and began breaking apart $200\text{ million}$ years ago.