Earth's Unique Structure and Continental Drift

These flashcards cover vocabulary related to Earth's structure, plate tectonics, and the theory of continental drift.

Continental Drift

The theory that continents are in constant motion and have slowly drifted into different positions over geologic time, originally proposed by Alfred Wegener.

Pangaea

A supercontinent that existed about 300 million years ago, consisting of all the present continents.

Crust

The outermost layer of the Earth, which is rocky and rigid, varying in thickness from 0-70 km.

Mantle

The layer of the Earth beneath the crust, composed of molten rock and the largest layer of the Earth.

Outer Core

The layer of the Earth that is extremely hot, made of liquid metal (iron and nickel), resembling the texture of warm honey.

Inner Core

The innermost layer of the Earth, approximately 6000 °C, consisting of solid metal due to high pressure from upper layers.

Divergent Boundaries

Plate boundaries where tectonic plates move apart, often creating new crust as magma seeps through.

Convergent Boundaries

Plate boundaries where tectonic plates move towards each other, leading to subduction or mountain formation due to collision.

Transform Boundaries

Plate boundaries where plates slide past each other laterally, which can result in earthquakes.

Lithosphere

The rigid outer layer of the Earth encompassing the crust and upper mantle.

Asthenosphere

A semi-fluid layer beneath the lithosphere, involved in tectonic plate movement.

Mesosphere

The zone of Earth's mantle located beneath the lithosphere and above the outer core, characterized by increasingly solid rock due to pressure.

Glacial Striations

Scratches or grooves in rock caused by glacial movement, providing evidence of past glacial activity.

Jigsaw Fit

A phenomenon where continents appear to fit together like pieces of a puzzle, supporting the theory of continental drift.

Fossil Correlation

The distribution of similar fossils across widely separated continents that supports the idea of continental drift.

Sea Floor Spreading

The process by which new oceanic crust is formed at mid-ocean ridges as tectonic plates move apart.