Geology chapter 6

Which of the following are true of felsic magmas?

All these are true of felsic magmas.

The largest concentration of composite volcanoes on Earth is located along the

Pacific Ring of Fire

Which of the following is NOT true about flood basalts?

They are fed from large interconnected composite volcanoes

Which of the following is NOT a characteristic of a volcanic dome?

They are one of the largest types of volcanoes.

Which of the following are ways that viscosity affects gases in magma?

Viscous magma prevents gas from escaping easily

What type of volcanic eruption is shown in this photograph?

a pyroclastic column

Which of the following is the best indicator that a volcano might be very dangerous?

a volcano that contains andesite and welded tuffs

Flood basalts influence life on Earth because:

all of these

Which of the following activities is NOT used to monitor volcanoes?

all of these

The most common volcanic rock found in lava flows on composite volcanoes is

andesite

What type of volcanic eruption is probably shown in this photograph?

basaltic lava flow

If bubbles cannot escape easily from a magma, the resulting eruption is likely to

be explosive

A relatively large, symmetrical volcano that contains interlayered lava flows, pyroclastic deposits, and volcanic mudflows is a

composite volcano

What types of rocks would be most common in the volcano in this photograph?

felsic and intermediate lava flows and tephra

Shield volcanoes commonly involve

fluid lava flows

When basaltic lavas reach the ocean they

form pillow basalts

Which of the following is NOT a rock typically found within calderas?

gabbro

Long, thin lava flows are typically produced by:

low-viscosity lavas

According to the fossil record, what events have coincided with the approximate times when flood basalts were erupting?

mass extinctions

What is the plate-tectonic setting of Mount Rainier?

subduction beneath the Pacific Northwest

A lava solidifies into nonvesicular basalt instead of vesicular basalt because

the lava has a low gas content

The higher the gas pressure builds in a magma

the more explosive an eruption it is likely to produce

What type of basaltic feature is shown in this photograph? (holes)

vesicles

Changes in topography, water chemistry, and gas output all are used to help predict

volcanic eruptions