R | GeologyRocks

Rare Earth Elements

Elements with atomic numbers 57 (Lanthanum) to 71 (Lutetium) inclusive plus scandium and yttrium.

Rayleigh Wave

A seismic surface wave which has a elliptical particle motion in the direction of travel. These are the waves that are responsible for the surface movement during an earthquake.

Regional Metamorphism

Metamorphism on a large scale involving heat and pressure.

Regolith

Loose material, such as dust and rock fragments, covering bedrock.

Regression

A lowering of sealevel observed in the geological record. See trangression.

Relative Age

The age of a rock or formation given relative to other rocks or formation, usually defined as a zone fossil name. See also Absolute age.

Relative sea level change

A local sea level change caused by a combination of global (eustatic) and local (isostatic) changes. This is the sea level variation "recorded" by the rock record.

Reproductive character displacement

Where a character used in species recognition differs more greatly between sympatric than between allopatric populations/species.

Reproductive Isolation

The situation where two populations are prevented or restricted from interbreeding by isolating mechanisms.

Reproductive Reinforcement

Evolution of enhanced reproductive isolation between populations due to natural selection.

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