GEOL 1001 Chapter 5

A vesicular igneous texture indicates that A. there was a lot of gas in the magma. B. the rock cooled quickly. C. the ash and pumice were hot and became compacted. D. the rock cooled slowly. E. the rock broke apart as it flowed.

A

As depth increases into the Earth A. there is an increase in temperature and pressure. B. there is an increase in pressure only. C. there is an increase in temperature and a decrease in pressure. D. there is an increase in temperature only.

A

Continental mantle plumes that are composed of felsic magma tend to be explosive when the Earth's surface is reached. These explosive eruptions create A. Calderas B. fissures C. plutons

A

What does this texture indicate about the formation of this rock? A. The magma formed some crystals before rising closer to the surface and solidifying. B. It formed from an explosive pyroclastic eruption. C. The rock solidified at great depth. D. The magma had abundant dissolved gas.

A

Which letter in this classification table indicates the position of gabbro? A. D B. A C. B D. C E. E

A

A mantle plume rises because A. it is molten and more dense than material around it. B.it is solid but less dense than material around it. C. it is mostly molten. D. it is propelled upward by gas coming out of the magma.

B

An ophiolite is A. a mixture of mafic and felsic magma within pillow basalts. B. a sliced-off piece of oceanic crust that has been thrust onto the edge of a continent or island. C. a mineral consisting of basalt and gabbro formed in the mantle.

B

An ophiolite is identical to A. a magma chamber, only it is formed beneath the ocean. B. a newly formed segment of oceanic crust, except it contains an additional layer of sediment. C. a combination of mafic and felsic magmas at depth lodged within sheeted dikes of basalt.

B

Use this graph that relates temperature and pressure to answer this question. What is required if a rock in position B moves to position A on the graph? A. Temperature would have to decrease and pressure increase. B. Temperature would have to decrease. C. Temperature would have to increase and pressure decrease. D. Temperature and pressure would have to increase.

B

When melting forms magma A. rocks in the source region generally are completely melted. B. partial melting produces a magma that is more felsic than the source. C. melting of the mantle generally produces felsic magma. D. melting of continental crust generally produces mafic magma. E. None of these choices are correct.

B

Which of the following igneous rocks would be formed by the fastest cooling? A. medium-grained granite B. very coarse granite pegmatite C. fine-grained granite D. volcanic glass E. coarse granite

B

The main source of heat energy for the Earth's interior is a direct result of A. beta decay, which is an unstable atom losing an electron. B. gamma decay, which is an unstable atom losing a photon. C. alpha decay, which is an unstable atom losing 2 protons and 2 neutrons.

C

Which of the following changes in conditions would cause melting of a solid rock? A. A to D B. B to C C. A to B D. A to C E. C to D

C

Which of the following choices is NOT true about magma chambers? A. Different magmas can mix within a magma chamber depending on their densities. B. Crystal setting occurs within magma chambers. C. Rock walls of magma chambers can withstand the intense heat and not melt.

C

How does the addition of water cause melting? A. It increases the temperature while decreasing the pressure. B. It heats the rocks. C. It decreases the pressure on the rocks. D. It changes the location of the liquid-solid boundary.

D

What does the texture of this rock indicate about its cooling history? The magma cooled A. slowly and under water. B. for a while at some depth and then rose to the surface where it finished solidifying. C. entirely at the surface. D. slowly under relatively deep conditions.

D

Which of the letters shown on this figure would most likely include some intermediate to felsic magmas? A. B, C, and D B. A and C C. B and C D. B, D, and E E. A, B, and C

D

Which of the magma systems shown is most likely to include felsic or intermediate magmas? A. A, B, and C B. B and C C. A and B D. C, D, andE E. B, C, and D

D

Which letter in this classification table indicates the position of rhyolite? A. A B. D C. E D. C E. B

E

Which of the magma systems shown is likely to contain mostly basalt? A. A B. B C. C D. All of the locations E. A and B only

E