ES1001 St Andrews

Vocab for Earth Sciences

Chemical weathering

The breakdown of rocks and minerals caused by chemical reactions, changing their chemical composition and turning them into new substances

Physical/mechanical weathering

The natural breakdown of rocks and minerals into smaller pieces without changing their chemical composition

Effusive eruptions

Slow, non explosive eruptions of lava onto the ground

Contact metamorphism

Rocks are altered by intense heat and chemically active fluids when hot magma pushes into the cooler surrounding crust

Regional metamorphism

Rocks are altered over broad areas by intense heat, confining pressure, and directed tectonic stress deep within the Earth's crust

Dynamic metamorphism

Mechanical deformation and high shear stress grind, fracture, and crush rocks along narrow fault zones

Burial metamorphism

Low-grade metamorphic process that happens when sedimentary and volcanic rocks are buried deep within thick sedimentary basins (typically 8 to 15 kilometers, or over 2,000 meters deep) under the weight of accumulating overlying layers

Hydrothermal metamorphism

Chemical and mineralogical change in rocks caused by the circulation of hot, mineral-rich water and steam

Shock metamorphism

Hypervelocity impact event—such as an asteroid or meteorite colliding with a planetary surface—sends a high-energy shock wave through the target material

Lithosphere

Earth’s crust— the plates constantly moving

Asthenosphere

Mechanically weak, ductile layer of Earth's upper mantle that lies directly beneath the rigid lithosphere

Transform boundary

Place where two tectonic plates slide horizontally past each other

Constructive/divergent boundary

Two tectonic plates move apart from each other

Destructive/convergent boundary

Two tectonic plates move into one another

Hot spot

An area on Earth's surface that experiences active volcanism because it sits above an unusually hot, rising column of mantle rock called a mantle plume, independent of tectonic plate boundaries

Ice sheet

A massive layer of glacial land ice that covers an area greater than 50,000 square kilometers— Greenland or Antarctic ice sheets

Interior plateau

The thickest, slowest moving middle part of a glacier

Outlet glacier

A faster moving channel of glacier surrounded by rock

Ice stream

Faster moving channel of glacier surrounded by more glacier

Ice shelf

Formation of floating ice still attached to larger glacier

Ice cap

Smaller ice sheets typically found in mountain highlands

Cirque glacier

The smallest kind of glacier, found in bowl-shaped depressions called cirques

Valley glacier

Glaciers that flow through and completely fill valleys and form U-shaped valleys

Fjord glacier

When a glacial valley is partially filled by the sea and the valley glacier terminates at the sea

Piedmont glacier

Delta of a glacier, valley glacier that flows into and fills lowlands

Active soil layer

Top layer of permafrost that melts in the summer and re-freezes in the winter

Leads

Open water channels formed in sea ice

Frazil

Ice needles that are the first step in sea ice formation

Basal slip

Water at the base of a glacier decreases friction and increases sliding

Glacial surges

Unknown cause, increase of glacial movement, most likely due to increased meltwater at the base

Ablation

Calving, melting, evaporation, sublimation, glaciers going away

Mass balance (glacier equation)

Accumulation - ablation

Equilibrium line (glaciers)

Separation line between accumulation area and ablation area

Temperate glacier

Ice at melting point, prone to melting

Polar glacier

Ice well below melting point, difficult to melt

Polythermal glaciers

Glaciers with some areas at melting point and some below— mixed melting pattern