Structure and Composition of Lithosphere

Vocabulary flashcards covering the structure and chemical composition of the lithosphere, Earth's internal layers, seismic discontinuities, and meteorological scales.

Lithosphere

The solid, outer part of the Earth, derived from the Greek words lithos ('rocky') and sphaeros ('sphere'), consisting of the crust and the brittle upper portion of the mantle.

Lithosphere-Asthenosphere Boundary (LAB)

The boundary where geologists and rheologists mark the change in ductility between the rigid lithosphere and the underlying viscous asthenosphere.

Ductility

A property measuring a solid material's ability to deform or stretch under stress.

Oceanic Lithosphere

The portion of the lithosphere with a mafic composition (rich in iron and magnesium, mostly basalt and gabbro), a thickness of $5\text{--}10\,\text{km}$, a density of approximately $3.0\,\text{g/cm}^3$, and an age typically under $200\text{ million years}$.

Continental Lithosphere

The portion of the lithosphere with a felsic composition (rich in silica and aluminum, generally granitic), a typical thickness of about $200\,\text{km}$, a lower density of approximately $2.7\,\text{g/cm}^3$, and an age that can reach billions of years.

Crust

The outermost layer of the Earth, making up $0.5\text{--}1.0\%$ of Earth's volume and less than $1\%$ of its mass, with an average density of about $2.7\,\text{g/cm}^3$.

Sial

The group of lighter silicate minerals composed of silica and aluminium that make up the continental crust.

Sima

The group of heavier silicate minerals composed of silica and magnesium that make up the oceanic crust.

Abundance of Elements in Earth's Crust

The elemental abundance order by weight in the Earth's crust: Oxygen > Silicon > Aluminium > Iron > Calcium > Sodium > Potassium > Magnesium.

Abundance of Elements in Whole Earth

The elemental abundance order by weight across the entire Earth: Iron > Oxygen > Silicon > Magnesium > Nickel > Sulphur > Calcium > Aluminium.

Mantle

The layer extending from Moho's discontinuity to a depth of $2,900\,\text{km}$, comprising about $83\%$ of the Earth's volume and $67\%$ of its mass.

Asthenosphere

The upper portion of the mantle extending up to $80\text{--}200\,\text{km}$ that is highly viscous, mechanically weak, and ductile, serving as the primary source of magma for volcanic eruptions.

Outer Core

The liquid layer of molten iron and nickel surrounding the inner core, with a thickness of about $2,200\text{--}2,300\,\text{km}$, whose movement generates Earth's magnetic field.

Inner Core

The solid, innermost layer of Earth with a radius of about $1,220\,\text{km}$, composed mainly of iron ($\text{Fe}$) and nickel ($\text{Ni}$) under extreme pressure, reaching temperatures of $5000\text{--}6000\,^\circ\text{C}$.

Discontinuities

Transition zones separating internal layers of the Earth that differ in physical and chemical properties such as temperature and density.

Conrad Discontinuity

The seismic discontinuity located between the upper crust and lower crust.

Mohorovičić Discontinuity

The seismic discontinuity located between the lower crust and upper mantle.

Repetti Discontinuity

The seismic discontinuity located between the upper mantle and lower mantle.

Gutenberg Discontinuity

The seismic discontinuity located between the lower mantle and outer core.

Lehmann Discontinuity

The seismic discontinuity located between the outer core and inner core.

Microscale

An atmospheric scale encompassing very small atmospheric processes with horizontal dimensions from a few meters to a few kilometers and lasting from a few seconds to several minutes.

Mesoscale

An atmospheric scale dealing with weather phenomena occurring over areas from several kilometers to a few hundred kilometers and persisting from minutes to a few hours.

Synoptic Scale

An atmospheric scale covering large weather systems extending across hundreds to thousands of kilometers and lasting from several days to about a week.

Planetary Scale

The largest atmospheric scale, involving global systems extending across continents or the entire globe and persisting for weeks, months, or longer.