Geology Questions

haven't erupted in many years and show no signs of any future eruptions.

• Mantle Plumes (Hot Spots) - Hawaii, Yellowstone.• Basaltic magma/lava.

• Decompression Melting.• Effusive eruptions of basaltic magmas and pillow lavas.• Formation of most of the sea floor.• Mid-oceanic ridges, Iceland.

if it hasn't erupted in many thousands of years but is expected to erupt in the future.

if currently or recently eruptive (Approximately 500 in the world today).

• Most large well - known volcanoes.• Explosive composite volcanoes.• Viscous andesitic lavas.

Volcanic rock in parallel, usually vertical columns, mostly six-sided; also called columnar structure

A basinlike depression over a vent at the summit of a volcanic cone.

An eruption in which lava erupts out of a vent on the side of a volcano.

A lava flow characterized by a ropy or billowy surface.

• Small and steeply sloping.• Composed of a pile of loose cinders; basalt is common.A volcano constructed of loose rock fragments ejected from a central vent.

A hill or mountain constructed by the extrusion of lava or rock fragments from a vent; landforms formed by the extrusion of lava.

Silica-deficient igneous rock or magma with a relatively high content of magnesium, iron, and calcium.

very low viscosity and flows very easily from erupting fissures; Layers of basalt flows that have built up to great thicknesses.

Pyroclasts in the 2-64 millimeter size range (singular, lapillus).

Igneous rock or magma with a chemical content between felsic and mafic compositions.

Major belt around the edge of the Pacific Ocean on which most composite volcanoes are located and where many earthquakes occur.

Tunnel-like cave within a lava flow. It forms during the late stages of solidification of a mafic lava flow.

• Moderately to steeply sloping.• Constructed of alternating layers of pyroclastic debris and solidified lava flows.• Composed primarily of intermediate composition volcanic rocks (for example, andesite).• Most common type of volcano at convergent plate boundaries.• Mainly located around the Pacific Ocean (Ring of Fire) and Mediterranean Sea.A volcano constructed of alternating layers of pyroclastics and rock solidified from lava flows.

Rocks, generally basalt, formed in pillow-shaped masses fitting closely together; caused by underwater lava flows.