OREGON STATE UNIVERSITY

Glossary beginning with T

Volcano Term Definitions

t
Talus

A slope formed a the base of a steeper slope, made of fallen and disintegrated materials.

Tephra

Materials of all types and sizes that are erupted from a crater or volcanic vent and deposited from the air.

Tephrochronology

The collection, preparation, petrographic description, and approximate dating of tephra.

Tilt

The angle between the slope of a part of a volcano and some reference. The reference may be the slope of the volcano at some previous time.

Trachyandesite

An extrusive rock intermediate in composition between trachyte and andesite.

Trachybasalt

An extrusive rock intermediate in composition between trachyte and basalt.

Trachyte

A group of fine-grained, generally porphyritic, extrusive igneous rocks having alkali feldspar and minor mafic minerals as the main components, and possibly a small amount of sodic plagioclase.

Tremor

Low amplitude, continuous earthquake activity often associated with magma movement.

Tsunami

A great sea wave produced by a submarine earthquake, volcanic eruption, or large landslide.

Tuff

Rock formed of pyroclastic material.

Tuff Cone

A type of volcanic cone formed by the interaction of basaltic magma and water. Smaller and steeper than a tuff ring.

Tuff Ring

A wide, low-rimmed, well-bedded accumulation of hyalo-clastic debris built around a volcanic vent located in a lake, coastal zone, marsh, or area of abundant ground water.

Tumulus

A doming or small mound on the crest of a lava flow caused by pressure due to the difference in the rate of flow between the cooler crust and the more fluid lava below