Exam 8: Volcanoes and Plutons

Gentle eruptions of basaltic lava from long fissures create __________.

The periodicity of Yellowstone eruptions, the presence of shallow magma, and the well-known tendency of magma of this type to erupt multiple times all suggest that a fourth eruption may occur.

Granitic magma has longer chains of silicate tetrahedra than basaltic magma.

If lava solidifies before the gas in it escapes, the bubbles are preserved as holes called __________.

Granitic magma has a __________ melting temperature compared to basaltic magma.

Lava with a smooth, ropy surface is:

A caldera is a:

If basaltic magma is too viscous to form a lava plateau, but still quite fluid, it heaps up slightly, forming:

The gentlest, least catastrophic type of volcanic eruption occurs when magma is so fluid that it simply oozes from cracks as pyroclastic rocks.

Increased temperature is the most important factor in magma production.

A sill forms when magma oozes between layers of country rock.

Shield volcanoes are relatively small compared to other volcanoes.

The Ring of Fire, a zone of concentrated volcanic activity encircling the Pacific Ocean basin, is located adjacent to __________.

Granitic magma contains __________ water than basaltic magma.

If magma contains large amounts of water, the water escapes as the magma rises, and the solidification temperature lowers, causing the magma to erupt.

__________ are pyroclastic volcanic fragments that vary in size from 4 to 32 millimeters.

A composite cone:

A pluton with an outcrop area of more than 100 square kilometers is a:

When an ash flow comes to a stop, most of the gas escapes into the atmosphere, leaving behind a chaotic mixture of volcanic ash and rock fragments called __________.

A/an __________ forms when magma oozes between layers of country rock as a sheet parallel to the layering.