chapter 6 volcanoes 3 reading quiz

__________ are steep-sided, symmetrical volcanic peaks built of alternating layers of pyroclastic debris capped by high-viscosity andesitic to rhyolitic lava flows that solidify to form protective caps. Stratovolcanoes Scoria cones Shield volcanoes Calderas

Stratovolcanoes

Identify the parts of table by dragging the answers that identify the parts of the volcanic materials to the appropriate space below.

TABLE 6.5

Drag the text boxes into their proper place in the chart according to the amount of viscosity and volatiles that each type of volcano contains.

TABLE 6.6

Slow flowing, more viscous basaltic lava commonly has a rough, blocky texture called ________. aa bb cc pahoehoe poi

aa

A caldera collapse occurs ________________. before the eruption starts in the middle of the eruption after the magma chamber is mostly empty millions of years after the volcano's final dying eruption at the onset of Vulcanian activity

after the magma chamber is mostly empty

If all of the following rocks were to completely melt and reach the same final temperature, which would produce magma with highest viscosity? basalt gabbro andesite diorite rhyolite

rhyolite

Label the parts of this idealized cross section by dragging the answers that identify the parts of the diagram to the appropriate space below.

FIGURE 6.2

Match the following volcano dangers to the correct definition. Lava flow lahars pyroclastic flow ___ rapid rush of gases and materials downslope ___ muddy water-laden rush of material downslope ___ molten rock moving downslope

pyroclastic flow lahars lava flows

Place the following steps in the proper order to describe the formation of a volcanic caldera. ___ Plinian eruptions form along fractures surrounding the magma bulge ___ rock above emptier magma chamber collapses inward, forming a depression ___ magma ejects outward in pyroclastic flow and ash columns ___ magma builds up in a dome underneath the surface

2 4 3 1

Rock may melt by _______________. lowering the pressure on it raising its temperature increasing its water content All of these choices are correct.

All of these choices are correct.

Why does the magma from some volcanoes flow smoothly and relatively peacefully, while the magma from other volcanoes blasts forth violently and deals death over wide areas? differences in the chemical and mineral makeup of magmas variations in the temperature, water and gas content, and viscosity of magmas different geographic positions with respect to hot spots and edges of tectonic plates All of these choices are correct.

All of these choices are correct.

__________ melting occurs when a rock melts due to a lowering of pressure. Release Uplift Elevation Ascension Decompression

Decompression

Crater Lake, Oregon, fills the caldera of ____________ which collapsed about 7,600 years ago. Mt. Mazama Mt. Shasta Mt. St. Helens Mt. Baker Mt. Rainier

Mt. Mazama

Pyroclastic debris is __________. chucks of magma and rocks blown into the air by gas in a volcanic eruption solid pieces of rock contained within, and transported by, lava the SiO2-poor magma that remains as gas escapes lava as it flows the SiO2-rich magma that flows quickly down the side of a volcano

chucks of magma and rocks blown into the air by gas in a volcanic eruption

Most rifting occurs at spreading centers __________. in the interior of continents and subduction zones located below sea level on the margins of continents and hot spots

located below sea level

The presence of water ________ the melting point of rock. raises lowers does not change may raise or may lower

lowers

The following prompts all list ways that viscosity can be altered. Drag the prompts to the correct area. Less Viscous More Viscous ___ increase SiO2 contents ___ increase temperature ___ increase mineral crystal content

more Less more

In magma, __________ is the most abundant dissolved gas. water vapor (H2O) carbon dioxide (CO2) sulfur dioxide (SO2) hydrogen sulfide (H2S) carbon monoxide (CO)

water vapor (H2O)

A shield volcano has a great ___________. height compared to its width width compared to its height amount of pumice proportion of pyroclastic material, compared with lava flows

width compared to its height

The viscosity of magma is lowered by __________. increasing temperature decreasing crystal content decreasing SiO2 content All of these choices are correct.

All of these choices are correct.

Match the type of magma with both the color of rock expected and the temperature of the magma below. Basaltic Andesite Rhyolitic ___1,000-1,300 degrees C ___800-1,000 degrees C ___medium gray ___600-900 degrees C ___light colored ___black to dark gray

Basaltic Andesite Andesite Rhyolitic Rhyolitic Basaltic

The formation of a giant continental caldera includes all but which of the following? Rising magma forms a low-density cap rich in SiO2 and gases, bulging the ground surface upward. Basaltic eruptions begin forming circular fractures surrounding the bulge. Magma pours out in high-volume pyroclastic flows, causing the ground surface to sink into a caldera. Removal of magma decreases the pressure on the magma below the caldera, causing new magma to bulge up the caldera floor.

Basaltic eruptions begin forming circular fractures surrounding the bulge.

Which of the following can help make rocks melt beneath Earth's surface? Decreasing pressure Increasing pressure Adding volatiles Increasing temperature Increasing density

Decreasing pressure Adding volatiles Increasing temperature

Drag the correct type of volcano to match the 3 Vs associated with it.

TABLE 6.8

Which of following correctly lists the order in which the listed minerals form in a cooling magma from the first to the last to form? quartz, biotite mica, amphibole, pyroxene, and olivine olivine, pyroxene, amphibole, biotite mica, and quartz pyroxene, biotite mica, calcite, quartz, and potassium-rich feldspar quartz, potassium-rich feldspar, pyroxene, biotite mica, and calcite

olivine, pyroxene, amphibole, biotite mica, and quartz