GeologyRocks

Geophysics

A branch of geology where non-invasive techniques such as magnetics, gravity surveys and seismic surveys are used to map unseen geological structures, such as faults.

Isostacy

The study of the responses of the Earth to loads (mountain belts, glaciers) placed on it. Isostatic theory states that at the depth of compensation all pressures exerted by rocks above are equal. Northern Europe is currently re-bounding from glaciers that were there during the Last Glacial Maximum, such that Scotland is raising and Kent is sinking.

Mantle

The layer beneath the crust, but above the core in the interior of the Earth. It's composition is broadly that of ultrabasic rocks.

Moho

See Mohorovičić discontinuity.

Mohorovičić discontinuity

The Mohorovičić discontinuity, usually referred to as the Moho, is the boundary between the Earth's crust and the mantle. The Moho serves to separate both oceanic crust and continental crust from underlying mantle. The Mohorovičić discontinuity was first identified in 1909 by Andrija Mohorovičić, a Croatian seismologist, when he observed the abrupt increase in the velocity of earthquake waves (specifically P-waves) at this point.

P-Wave

A seismic body wave which propagate like sound waves, i.e. by compression and extension in the direction of travel. They can travel through solids and liquids and are the fastest of the seismic waves.

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.

S Wave

A seismic body wave that has motion perpendicular to the direction of travel (i.e. like light waves). They cannot travel through liquids and are slower than P Waves.

Seismology

The study of earthquakes and the structure of the earth via seismic waves. This covers whole earth structure (global seismology) and crustal structure (exploration seismology). Exploration seismology is used in commercial operations, such as oil exploration.

There are two types of seismic waves that travel through the interior of the Earth; P-waves and S-waves.