Exam 2 Material

Stratovolcanoes can create several volcanic hazards both during and after eruption events. Based on the animation, place the following volcanic hazards in chronological order based on when they would likely impact a town near the volcano after an eruption occurs.

1. a pyroclastic flow of lapilli and super heated gases 2. a lahar formed from volcanic ash mixing with quickly melted snow and ice 3.volcanic ash distributed by wind 4. a landslide caused by the collapse of coherent lava and friable ash deposits

How can pyroclastic debris cause casualties close to an explosive eruption? Choose one: A. Areas can be buried in lapilli and several meters of ash. B. Ash can coat the leaves of trees. C. Lava can fall from the sky and kill people. D. Areas can experience ash fall that adds toxic poisons to the soil.

A. Areas can be buried in lapilli and several meters of ash.

Which of the following statements are true about partial melting? Choose one or more: A. As more of the rock melts during partial melting, the magma becomes more mafic than the original melt that formed. B. Mafic components of the parent rock tend to go into the liquid state first during partial melting. C. Partial melting results in magmas that are more felsic in composition than the parent rock. D. Felsic components of the parent rock tend to go into the liquid state first during partial melting.

A. As more of the rock melts during partial melting, the magma becomes more mafic than the original melt that formed. B. Mafic components of the parent rock tend to go into the liquid state first during partial melting. D. Felsic components of the parent rock tend to go into the liquid state first during partial melting.

How are continental hot-spot volcanoes different from oceanic hot-spot volcanoes? Choose one: A. Continental hot spots are extremely explosive while oceanic hot spots have more passive lava flows. B. Continental hot spots do not produce much eruptive material compared to oceanic hot spots. C. Continental hot spots are more mafic than oceanic hot spots. D. Continental hot spots are much smaller than oceanic hot spots.

A. Continental hot spots are extremely explosive while oceanic hot spots have more passive lava flows.

Why don't geologists refer to sand on a beach as a rock? Choose one: A. Sand on a beach is composed of loose, unconsolidated minerals. B. The sand grains are not composed of minerals typically found in rocks. C. The sand is only partially lithified. D. Beach sand does not occur naturally.

A. Sand on a beach is composed of loose, unconsolidated minerals.

Explain why the oval-shaped dark rock (X) looks like it's resting on the chimney-like column. Choose one: A. The oval-shaped rock is a little more resistant to weathering processes than the column below it. B. The oval-shaped rock was placed on top of the column by humans. C. The oval-shaped rock was moved on top of the column during a massive flood event. D. Grains of sediment that make up the oval-shaped rock were moved by wind and deposited on top of the column.

A. The oval-shaped rock is a little more resistant to weathering processes than the column below it.

Gems like this diamond have smooth, reflective faces called facets. Which of the following best describes the origin of these surfaces? Choose one: A. They are produced by grinding and polishing. B. They are cleavage planes. C. They are natural crystal faces.

A. They are produced by grinding and polishing.

Which of the following are types of pyroclastic debris? Choose one or more: A. blocks B. lapilli C. lahar D. magma E. ash F. lava G. gas

A. blocks B. lapilli E. ash

A flat surface that bounds a crystal as it grows is referred to as a __________. Choose one: A. crystal face B. crystal structure C. crystal luster D. crystal habit

A. crystal face

Choose the most likely product of partially melting a rock of intermediate composition. Choose one: A. felsic magma B. ultra-mafic magma C. mafic magma D. a melt of the same composition as the original rock

A. felsic magma

Which type of silicate has the greatest proportion of oxygen atoms shared by pairs of adjacent tetrahedra? Choose one: A. framework silicates B. chain silicates C. sharing of oxygen atoms does not occur in silicates D. sheet silicates

A. framework silicates

This NASA image shows the amount of ash and aerosol ejected into the atmosphere by the June 15, 1991 eruption of Mount Pinatubo, Philippines. Warm colors represent higher concentrations. The most significant global consequence of ash and aerosol in the atmosphere is Choose one: A. global cooling via atmospheric haze. B. global crop failure via ash fallout. C. global warming via greenhouse gases.

A. global cooling via atmospheric haze.

What changes in the crust do scientists look for when using seismology and seismic networks to mitigate volcanic hazards? Choose one: A. noise/vibrations caused by magma moving through rocks B. lava flowing from a volcanic crater C. temperature changes in magma beneath the volcano D. the composition of gases coming from a volcano

A. noise/vibrations caused by magma moving through rocks

Which two of the following rocks are organic sedimentary rocks? Choose one or more: A. oil shale B. fossiliferous limestone C. siltstone D. coal E. chalk

A. oil shale D. coal

What is volcano-sedimentary debris? Choose one: A. previously deposited material that breaks up, travels downslope, and redeposits. B. material ejected out of a volcano and deposited from the cloud of debris C. lava flows deposited in sedimentary basins D. sedimentary rock that surrounds the volcano

A. previously deposited material that breaks up, travels downslope, and redeposits.

Unlike mid-ocean ridges, some continental rift volcanoes also produce felsic pyroclastic debris. Why? Choose one: A. Because felsic magma rises from the mantle into the continental crust. B. Because as basalt rises through continental crust, heat transfer partially melts the continental crust, creating a felsic magma. C. Because the material is directly from the lower mantle. D. Because there is no basalt beneath the continent.

B. Because as basalt rises through continental crust, heat transfer partially melts the continental crust, creating a felsic magma.

What causes the melting that provides the basalt lava extruded at mid-ocean ridges and along rifts? Choose one: A. Melting is the result of adjacent volcanoes that are at higher melting temperatures than the mid-ocean ridges. B. Melting is due to hot mantle rock rising to shallow depths beneath the ridge, which subsequently undergoes decompression melting. C. Flux melting of the asthenosphere creates the basaltic magma. D. Circulation of superheated oceanic water travels through the subsurface, melting the surrounding crust.

B. Melting is due to hot mantle rock rising to shallow depths beneath the ridge, which subsequently undergoes decompression melting.

How do chemical and physical weathering work together to cause the transition from rock to sediment? Choose one: A. Physical weathering decreases the surface area of rocks, making it easier for chemical weathering to take place and create sediment. B. Physical weathering exposes a greater surface area to chemical weathering, which speeds up chemical weathering. The chemical breakdown of minerals makes rocks weaker and easier to physically weather. C. Chemical weathering causes jointing in rocks, allowing physical weathering processes to take place and widen these cracks.

B. Physical weathering exposes a greater surface area to chemical weathering, which speeds up chemical weathering. The chemical breakdown of minerals makes rocks weaker and easier to physically weather.

How do evaporites form? Choose one: A. They form as silica is evaporated out of seawater. B. They form as ions (minerals) precipitate out of an evaporating solution. C. They form as salt is deposited on the slopes of a mountain. D. They form when a body of water is evaporated and re-precipitated in a different location.

B. They form as ions (minerals) precipitate out of an evaporating solution.

In which two ways can sedimentary rocks form? Choose one or more: A. freezing of molten rock B. cementing together of grains broken off pre-existing rocks C. precipitation of mineral crystals out of water solutions D. alteration of pre-existing rocks by heat and pressure

B. cementing together of grains broken off pre-existing rocks C. precipitation of mineral crystals out of water solutions

The dispersion of light of a gemstone is referred to as the gem's __________. Choose one: A. clarity B. fire C. carat D. quality

B. fire

What causes the difference between ruby and corundum? Choose one: A. formation temperature B. impurities in the mineral C. mineral structure D. formation pressure

B. impurities in the mineral

The hardness of a mineral is determined by Choose one: A. its ability to resist chemical reactions with other substances. B. its ability to resist being scratched by other substances. C. its ability to resist breaking when being struck with a hammer. D. its ability to form cleavage planes.

B. its ability to resist being scratched by other substances.

An igneous rock contains several different minerals. How often do they all crystallize at the same time? Choose one: A. under certain conditions B. never C. always

B. never

What characteristics define a mineral? Choose one or more: A. usually organic B. often inorganic C. molten rock D. naturally occurring E. solid F. crystalline material with a definable chemical composition

B. often inorganic D. naturally occurring E. solid F. crystalline material with a definable chemical composition

Biochemical sedimentary rocks are composed of the shells of dead organisms, but organic sedimentary rocks are composed of __________. Choose one: A. bones of dead organisms B. organic material/compounds of dead organisms C. living organisms D. tracks and burrows of dead organisms

B. organic material/compounds of dead organisms

Which of the following is a mineral? Choose one: A. lava B. salt C. sugar

B. salt

Which mineral class does quartz belong to? Choose one: A. carbonates B. silicates C. halides D. sulfides

B. silicates

The fundamental building block of silicate minerals, the most abundant minerals. What is it called? Choose one: A. hydroxide B. silicon-oxygen tetrahedron C. chloride anion D. carbonate anion

B. silicon-oxygen tetrahedron

The difference between a conglomerate and a breccia is __________. Choose one: A. a conglomerate is poorly sorted, whereas a breccia is well sorted B. a conglomerate is made of igneous clasts, whereas a breccia is made of metamorphic clasts C. a conglomerate has rounded grains, whereas the breccia has angular grains D. a conglomerate is mostly made of quartz, whereas a breccia is made mostly of calcite

C. a conglomerate has rounded grains, whereas the breccia has angular grains

Minerals are classified by specifying the principal __________. Choose one: A. cation or cation group B. mineral habit C. anion or anion group D. crystal structure

C. anion or anion group

How does a caldera form? Choose one: A. from magmatic shifts below the surface B. from a lava lake that drains out C. from eruptions that result int withdrawal of magmatic support in the crust, causing collapse D. from erosion of summit material

C. from eruptions that result int withdrawal of magmatic support in the crust, causing collapse

Galena's specific gravity is 7.5, that of quartz 2.65, and that of liquid mercury 13.6. Given equal-sized samples (volumes) of galena and quartz, which will feel heavier? Choose one: A. They will feel about the same. B. quartz C. galena

C. galena

An immensely thick succession of basalt flows, each of which spread over a vast area, is called a __________. Choose one: A. subaerial volcano B. flood basalt C. large igneous province D. dike swarm

C. large igneous province

Galena has specific gravity of 7.5, quartz has a specific gravity of 2.6, and liquid mercury has a specific gravity of 13.6. Which of these, if any, will float on water? Choose one or more: A. galena B. quartz C. none; all have a higher specific gravity than water D. liquid mercury

C. none; all have a higher specific gravity than water

What's the difference between a crystalline igneous rock and a clastic sedimentary rock? Choose one: A. Clastic sedimentary rocks have larger mineral grains and crystalline igneous rocks have smaller minerals. B. Crystalline igneous rocks are darker in color and clastic sedimentary rocks are lighter. C. Clastic sedimentary rocks contain only one mineral, whereas crystalline igneous rocks contain many minerals. D. Minerals in crystalline igneous rocks are held together by interlocking crystals, and in clastic sedimentary rocks grains are held together by cement.

D. Minerals in crystalline igneous rocks are held together by interlocking crystals, and in clastic sedimentary rocks grains are held together by cement.

Which type of basaltic lava flow has a ropy surface, and which a rubbly surface? Choose one: A. Both 'a'ā and pahoehoe lavas can be either ropy or rubbly. B. Pahoehoe lava has a rubbly or rocky surface. 'A'ā lava has a ropy surface. C. 'A'ā is always ropy but pahoehoe can be either ropy or rubbly. D. Pahoehoe lava has a ropy surface. 'A'ā lava has a rubbly or rocky surface.

D. Pahoehoe lava has a ropy surface. 'A'ā lava has a rubbly or rocky surface.

Why does the character of a soil depend on climate? Choose one: A. The amount of rainfall in an area will affect the type of chemical interactions that take place. B. The temperature and rainfall of an area determine how much physical weathering occurs. C. The temperature of an area will determine the types of minerals found in the soil. D. The distribution of rainfall and the temperature range determine the rate and amount of chemical weathering and leaching.

D. The distribution of rainfall and the temperature range determine the rate and amount of chemical weathering and leaching.

What would be the significance of finding a precipitated mineral on another planet? Choose one: A. The planet may have or have had significant weathering of its rocks. B. The planet may have or have had an Earth-like atmosphere. C. The planet may have or have had volcanic activity. D. The planet may have or have had liquid water on it.

D. The planet may have or have had liquid water on it.

Diamond and graphite (shown in photos D and E) have identical compositions—both consist of pure carbon. But these two minerals look and behave very differently. Why? A. One is euhedral and the other is anhedral. B. Graphite is different because it is softer. C. Diamonds are only used as gems. D. They are polymorphs, meaning their atoms are arranged in different crystal structures.

D. They are polymorphs, meaning their atoms are arranged in different crystal structures.

Which type of pyroclastic debris, which may consist of minuscule shards of glass, becomes tuff when lithified? Choose one: A. lahar debris B. lava C. blocks D. ash

D. ash

What are the two types of layering that can occur in rocks? Choose one or more: A. outcropping B. depositing C. sheeting D. bedding E. foliation

D. bedding E. foliation

Soil horizons are __________. Choose one: A. layers of soil distinguished by their thickness B. clumps of soil that contain more nutrients than the surrounding soil C. soil layers composed of different sediment sizes D. layers of soil that form at different depths due to different soil-forming processes

D. layers of soil that form at different depths due to different soil-forming processes

How does growth happen in a mineral crystal?

Growth occurs as atoms attach to the outer surface. In an open cavity, crystal faces grow perfectly.

Given that a mineral has three mutually perpendicular planes of cleavage and breaks into cubes, is the mineral mica, pyroxene, amphibole, halite, or calcite?

Halite

Obsidian is a volcanic glass that forms when lava cools very quickly and consists of a solid mass of glass through and through. Why is obsidian not classified as a mineral? Choose one: The atoms or molecules in obsidian do not have a crystalline structure. Obsidian is not naturally occurring since it is only associated with volcanoes. Obsidian does not have a definable chemical composition because it only comes from lava. Obsidian contains carbon-to-hydrogen bonds.

The atoms or molecules in obsidian do not have a crystalline structure.

What are the criteria for being a mineral?

They are naturally occurring, (mostly) inorganic crystalline solids formed by geologic processes and with a definite chemical composition.

The silica-oxygen tetrahedra is the building block of which chemical class of minerals? Choose one: carbonates oxides silicates sulfates

silicates

Lahars are a volcanic hazard that can occur both during an eruption and while a volcano is dormant. Which event below must happen for a lahar to form while a volcano is dormant? Choose one: the opening of a fissure in the flank of the dormant volcano the slope of the dormant volcano's flank exceeds its angle of repose the dormant volcano reaches isostasy very heavy rainfall over the dormant volcano

very heavy rainfall over the dormant volcano