Exam 4: Volcanism and Extrusive Rocks

A _________, a mixture of gas and volcanic debris, may blast out laterally under a viscous plug capping a volcano.

Columnar jointing is a characteristic of basalt lava.

Occasionally, a volcano will spew large amounts of fine volcanic dust into the high atmosphere. This dust can have the effect of __.

Individual layers of basalt lava may be divided into vertical columns called ______.

Earth is the only major body in the solar system on which there are active volcanoes.

In 1902 the port city of St. Pierre on the island of Martinique was destroyed by a ___.

Measurements indicate that the worldwide average temperature dropped about a half degree Celsius for a couple of years after the eruption of Mt. St. Helens.

What are the three factors that influence viscosity of a lava?

_____ describes the surface of a basalt flow with a smooth ropy surface.

Condensation of the water vapor by degassing magma during the time following Earth's formation produced the ____.

Major volcanic peaks of the Cascade Mountains, like Mt. Rainier, Mt. Shasta, Mt. Hood, and Mt. St. Helens, have been active volcanoes for 30 to 40 million years.

Volcanic domes are steep-sided, spine-shaped masses of volcanic rock formed from _______ magma.

Crater Lake is a volcanic feature of _____.

A ________ igneous rock is one in which larger crystals are enclosed in a groundmass of much finer-grained material.

________ is a frothy volcanic glass with so much void space that it can actually float.

The islands of Hawaii are essentially a series of shield volcanoes built upward from the ocean floor over millions of years.

Basalt is the most common mafic rock.

The islands of the Hawaiian chain are an excellent example of a series of __.

A ______ is a volcano constructed of pyroclastic fragments ejected from a central vent.

Most of the gas released by volcanic eruptions is sulfur dioxide.