GeologyRocks

Stratigraphy

The study of layered sedimentary or metamorphic rocks and how they related to each other, particularly their ages.

Transgression

A raising of sea level observed in the geological record. See regression.

Triassic

The first period of the Mesozoic. Spans 251-199Ma.

Unconformity

A break in the stratigraphic record which represents a period of no sediment deposition. The interval of geologic time not represented is called a hiatus.

There are three types of unconformities: disconformity, nonconformity, and angular unconformity.

Unloading

Unloading usually results in pressure release formations. A good example is the tilting of the UK due to the removal of ice sheets in the north. Scotland is moving upwards, southern Britain is moving downwards. The evidence can be seen in raised beaches in Scotland, which gives the past sea level.

Volcano

A point on the Earth's surface where magma erupts and accumulates.

Wadi

A wadi is a river bed in an arid region that is dry apart from times of high rainfall. The term is Ariabic in origin. The result of a flash flood is a poorly sorted sediment, which can contain substantial boulders.

Weathering

The process of disintegrating rocks in the near surface by chemical or physical means.

Yazoo

A tributary that runs parallel to the main river for some distance.