Which of the following factors helps magma rise toward

Problem 104MCQ For the letters on this figure, choose the likely cause of melting for site A. A. Decompression melting as the mantle rises B. Melting by adding water C. Melting of continental crust caused by an influx of mantle-derived magmas

Problem 105MCQ For the letters on this figure, choose the likely cause of melting for Site B. A. Decompression melting as the mantle rises B. Melting by adding water C. Melting of continental crust caused by an influx of mantle-derived magmas

Problem 108MCQ For the letters on this figure, choose the likely cause of melting for Site E. A. Decompression melting as the mantle rises B. Melting by adding water C. Melting of continental crust caused by an influx of mantle-derived magmas

Problem 2MCQ What texture is displayed by the igneous rock in this photograph? A. vesicles B. breccia C. porphyritic D. glassy E. none of these

Problem 5MCQ What texture is displayed by the igneous rock in this photograph? A. vesicles B. breccia C. porphyritic D. glassy E. none of these

Problem 8MCQ What does this welded texture indicate about the formation of this rock? A. It formed from an explosive pyroclastic eruption. B. The rock solidified at great depth. C. The magma formed some crystals before rising closer to the surface and solidifying. D. The magma had abundant dissolved gas.

Problem 7MCQ What does this texture indicate about the formation of this rock? A. It formed from an explosive pyroclastic eruption. B. The rock solidified at great depth. C. The magma formed some crystals before rising closer to the surface and solidifying. D. The magma had abundant dissolved gas.

Problem 3MCQ What texture is displayed by the igneous rock in this photograph? A. vesicles B. breccia C. porphyritic D. glassy E. none of these

Problem 6MCQ What does this texture indicate about the formation of this rock? A. It formed from an explosive pyroclastic eruption. B. The rock solidified at great depth. C. The magma formed some crystals before rising closer to the surface and solidifying. D. The magma had abundant dissolved gas.

Problem 4MCQ What texture is displayed by the igneous rock in this photograph? A. vesicles B. breccia C. porphyritic D. glassy E. none of these

Problem 9MCQ The site on the accompanying figure that would most likely form a rock with large crystals is: A. A B. B C. C D. D E. E

Problem 10MCQ The site on the accompanying figure that would mostly likely form a rock that is fine grained (has small crystals but is not glassy) is: A. A B. B C. C D. D E. E

Problem 11MCQ The site on the accompanying figure that would most likely form a rock that is glassy with no volcanic ash is: A. A B. B C. C D. D E. E

Problem 12MCQ The site on the accompanying figure that would most likely form a rock that has a nonwelded texture with many fine particles is: A. A B. B C. C D. D E. E

Problem 14MCQ A finely crystalline or glassy igneous texture indicates that: A. there was a lot of gas in the magma B. the rock cooled quickly C. the rock broke apart as it flowed D. the rock cooled slowly E. the ash and pumice were hot and became compacted

Problem 15MCQ A vesicular igneous texture indicates that: A. there was a lot of gas in the magma B. the rock cooled quickly C. the rock broke apart as it flowed D. the rock cooled slowly E. the ash and pumice were hot and became compacted

Problem 13MCQ The site on the accompanying figure that would most likely form a rock that has a welded texture is: A. A B. B C. C D. D E. E

Problem 16MCQ Coarsely crystalline igneous textures indicate that: A. there was a lot of gas in the magma B. the rock cooled quickly C. the rock broke apart as it flowed D. the rock cooled slowly E. the ash and pumice were hot and became compacted

Problem 17MCQ A welded igneous texture indicates that: A. there was a lot of gas in the magma B. the rock cooled quickly C. the rock broke apart as it flowed D. the rock cooled slowly E. the ash and pumice were hot and became compacted

Problem 18MCQ A volcanic breccia texture indicates that: A. there was a lot of gas in the magma B. the rock cooled quickly C. the rock broke apart as it flowed D. the rock cooled slowly E. the ash and pumice were hot and became compacted

Problem 19MCQ An igneous pegmatite indicates that: A. there was water in the magma B. the rock cooled slowly and then quickly C. the rock broke apart as it flowed D. the rock cooled quickly E. the ash and pumice were hot and became compacted

Problem 24MCQ Which of the following rock types requires dissolved gas in the magma? A. granite B. pumice C. gabbro D. diorite E. andesite

Problem 20MCQ A porphyritic igneous texture indicates that: A. there was water in the magma B. the rock cooled slowly and then quickly C. the rock broke apart as it flowed D. the rock cooled slowly E. the ash and pumice were hot and became compacted

Problem 26MCQ Which of the following rock types does NOT involve dissolved gas in the magma? A. tuff B. pumice C. scoria D. diorite E. vesicular basalt

Problem 25MCQ Which of the following igneous rocks can be composed of fragments? A. tuff B. scoria C. volcanic breccia D. all of these

Problem 27MCQ Which of the following can occur within a magma chamber? A. Sinking or floating crystals may change the composition of the remaining magma. B. Wall rocks can melt and become incorporated into the magma. C. If two magmas mix, the resulting magma would be between the composition of the two magmas. D. All of these.

Problem 23MCQ Which of the following photographs depicts an igneous rock where the magma cooled slowly at first and then had fast cooling? A. B. C. D.

Problem 22MCQ Which of the following rock photographs depicts an igneous rock that trapped gas? A. B. C. D.

Problem 28MCQ Which letter in this classification table indicates the position of granite? A. A B. B C. C D. D E. E

Problem 29MCQ Which letter in this classification table indicates the position of rhyolite? A. A B. B C. C D. D E. E

Problem 21MCQ Which of the following rock photographs depicts a felsic igneous rock? A. B. C. D.

Problem 30MCQ Which letter in this classification table indicates the position of andesite? A. A B. B C. C D. D E. E

Problem 31MCQ Which letter in this classification table indicates the position of gabbro? A. A B. B C. C D. D E. E

Problem 32MCQ Which letter in this classification table indicates the position of basalt? A. A B. B C. C D. D E. E

Problem 33MCQ Which of the following processes has added heat to Earth's interior during or after its formation? A. collision of asteroids and meteoroids with Earth B. formation and sinking of masses of iron and nickel C. radioactive decay D. all of these

Problem 34MCQ The main process that happens during the alpha type of radioactive decay is: A. an electron is given off B. an electron is absorbed and turned into a neutron C. an atom splits into two pieces D. an alpha particle combines with a small atom to make a larger one

Problem 36MCQ Which number of this figure indicates transfer of thermal energy by conduction? A. 1, heating of adjacent rocks by a magma B. 2, cooling of hot lithosphere by contact with cooler rocks and seawater C. 3, heating of the subducted plate by contact with hotter overlying materials D. all of these

Problem 37MCQ Which of the following is the best example of heat transfer by conduction? A. a pan is placed directly on a burner B. water within the pan flows in a circular path C. a burner gives heat through the air without touching the object D. seawater is drawn into a mid-ocean ridge

Problem 38MCQ Which of the following is the best example of heat transfer by conduction? A. newly created lithosphere loses heat to adjacent rocks B. water flows in a circular path in a pan C. a burner gives heat through the air without touching the object D. seawater is drawn into a mid-ocean ridge

Problem 35MCQ Which number on this figure indicates heating by conduction? A. 1, direct contact between the burner and the pan B. 2, heating by thermal radiation through the air C. 3, heated water expands and rises to the top of the pan and then cools and flows back down D. 4, moving a pan of water away from the stove

Problem 39MCQ Which number on this figure indicates transfer of thermal energy by a convection cell? A. 1, direct contact between the burner and the pan B. 2, heating by thermal radiation through the air C. 3, heated water expands and rises to the top of the pan and then cools and flows back down D. 4, moving a pan of water away from the stove

Problem 40MCQ Which of the following is an example of heat transfer by convection? A. water within a pan is heated and flows in a circular path B. seawater is drawn into a mid-ocean ridge, heated, and rises C. the rise of material beneath mid-ocean ridges coupled with subduction D. all of these

Problem 43MCQ Which of the following changes in conditions would represent heating during burial? A. from A to B B. from B to C C. from C to D D. from D to A E. from A to C

Problem 42MCQ Which of the following changes in conditions indicates heating of the rock? A. from A to B B. from B to C C. from C to D D. from D to A E. none of these

Problem 41MCQ Which of the following changes in conditions would cause melting of a solid rock? A. from A to B B. from B to C C. from C to D D. from A to D E. from A to C

Problem 45MCQ The liquid-solid boundary on this graph slopes down and to the right because: A. temperature increases down in the earth B. temperature decreases down in the earth C. pressure increases down in the earth D. none of these

Problem 44MCQ Which of the following changes in conditions could represent melting of continental crust from the introduction of a mafic magma? A. from A to B B. from A to C C. from A to D D. from C to B E. from B to D

Problem 47MCQ How could a rock at point C be melted? A. increase in temperature B. decrease in pressure C. increase in temperature accompanied by a decrease in pressure D. all of these

Problem 46MCQ Which of the following changes in conditions represents decompression melting? A. from A to B B. from B to A C. from B to C D. from C to B E. from D to A

Problem 49MCQ How does the addition of water cause melting? A. it heats the rocks B. it decreases the pressure on the rocks C. it increases the temperature while decreasing the pressure D. it changes the location of the liquid-solid boundary

Problem 48MCQ Which of the following changes in conditions represents the main cause of melting beneath mid-ocean ridges? A. from A to B B. from A to C C. from A to D D. from C to B E. from D to B

Problem 50MCQ Which of the following acts to keep a rock solid (instead of melting)? A. an increase in temperature B. an increase in the vibration within a lattice C. an increase in confining pressure D. none of these

Problem 51MCQ What does the texture of this rock indicate about its cooling history? The magma cooled: A. entirely at the surface B. for a while at some depth and then rose to the surface where it finished solidifying C. slowly under relatively deep conditions D. slowly in the presence of water

Problem 52MCQ What does the texture of this rock indicate about its cooling history? The magma cooled: A. entirely at the surface B. for a while at some depth and then rose to the surface where it finished solidifying C. slowly under relatively deep conditions D. slowly and underwater

Problem 53MCQ 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

Problem 55MCQ Which of the following processes could result in a felsic magma? A. partial melting of an intermediate-composition source B. partial melting of continental crust C. formation and settling of mafic crystals in an intermediate magma D. all of these

Problem 56MCQ Which are important ways that magma can raise through the crust? A. through fractures that can form dikes B. pieces of the wall rocks that break off and provide space C. tectonic forces can help open pathways D. magma is hotter and less dense than its surrounding E. all of these

Problem 54MCQ Which of the following is common during crystallization of a magma? A. felsic minerals crystallize first B. mafic minerals are light and float in most magma chambers C. felsic crystals are heavy and sink in most magma chambers D. all crystals form at about the same time E. none of these

Problem 57MCQ Which of the following factors helps magma rise toward Earth's surface? A. pressure decreases with increasing depth B. magma is more dense and therefore tougher than the surrounding solid rocks C. gas bubbles generally form at great depth and drive magma upward D. none of these

Problem 58MCQ Which of the following causes magma to be less viscous? A. a lower temperature B. fewer silicate chains in the magma C. a more felsic composition D. a higher percentage of crystals E. none of these

Problem 59MCQ Which of the following is likely to be true about the magma that formed the left volcanic feature compared to the right one in this figure? A. the magma has a higher viscosity B. the magma has a higher silicate content C. the magma is probably more felsic D. all of these

Problem 63MCQ Which of the following minerals would likely crystallize early from magma? A. mafic minerals B. quartz C. muscovite D. potassium feldspar

Problem 62MCQ What is a path for magma as it solidifies at great depth and then is uplifted slowly toward the surface? A. from B to A B. from C to A C. from C to B to A D. from D to C to B E. from D to C to A

Problem 64MCQ Which of the following is NOT a way that magma can lose heat to begin solidifying? A. conduction to surrounding solid rocks B. loss of thermal energy to the air and water C. water that is heated and circulated near the magma D. an increase in the rate of radioactive decay

Problem 60MCQ Which of the following is likely to be true about the left volcanic feature compared to the right one in this figure? A. the magma has a higher viscosity B. the magma has fewer silicate chains C. the magma probably formed at a higher temperature D. all of these

Problem 65MCQ Which of the following igneous rocks would be formed by the fastest cooling? A. very coarse granite pegmatite B. coarse granite C. medium-grained granite D. fine-grained granite E. volcanic glass

Problem 66MCQ Which of the following igneous rocks would be formed by the slowest cooling? A. coarse granite B. medium-grained granite C. fine-grained granite D. volcanic glass E. there is not enough information to tell

Problem 69MCQ Which of the following igneous rocks is NOT characteristic of mid-ocean ridges? A. finely crystalline rocks that formed in dikes B. gabbro that solidified in a magma chamber C. pillow basalt D. andesite and granodiorite

Problem 70MCQ Which of the following is characteristic of continental rifts? A. some magmas are felsic and intermediate B. heat from hot, mafic magma can melt continental crust C. solid asthenosphere undergoes decompression melting D. all of these

Problem 61MCQ On this figure of Bowen's Reaction Series, which mineral would crystallize last from magma? A. 1, olivine B. 2, calcium-rich plagioclase C. 3, sodium-rich plagioclase D. 4, K-feldspar

Problem 67MCQ Which of the following igneous rocks has a texture consistent with a magma that cooled and solidified slowly at first, followed by more rapid cooling? A. small felsic crystals enclosed in large mafic ones B. small mafic crystals enclosed in large felsic ones C. large crystals like those in pegmatite D. large, early formed crystals surrounded by smaller, late formed crystals

Problem 72MCQ What generally happens when subduction-derived magma encounters thick continental crust? A. most magma reaches the surface with minor modification B. the magma solidifies in sheeted dikes with a composition of basalt C. the magma interacts with the crust, forming felsic or intermediate compositions D. the oceanic crust melts

Problem 71MCQ The main cause of melting along subduction zones is the: A. rise and decompression melting of mantle lithosphere B. rise and decompression melting of mantle asthenosphere C. melting of the subducting plate D. release of water from the subducting plate

Problem 74MCQ The main way water gets into a subduction zone is by: A. heating of the overlying continental crust B. a decrease in pressure that causes melting C. rain associated with eruptions in the island arc D. seawater introduced into oceanic crust at the mid-ocean ridge, prior to subduction E. all of these

Problem 68MCQ Which of the following is true about igneous processes along oceanic divergent boundaries as shown in this figure? A. Oceanic crust moves toward the ridge in a conveyor-belt manner. B. Most of the mantle is molten, not solid. C. Solid asthenosphere rises as plates move apart. D. Magma generated in the crust drips down into the mantle.

Problem 73MCQ Which of the following settings is most likely to have eruptions of basalt? A. island arcs B. subduction beneath a thin continental plate C. subduction beneath a thick continental plate D. mid-ocean ridge E. none of these

Problem 75MCQ Which of the following occurs during a continental collision, after any subduction has ended? A. the descending continental plate gets hotter and decreases in pressure B. decreasing pressure causes downgoing crust to melt C. volcanoes are widespread above continental collisions D. all of these E. none of these

Problem 76MCQ Hot spots in oceanic settings typically produce: A. flood basalts in the middle of a continent B. huge caldera explosions C. island arcs D. lines or clusters of volcanic islands

Problem 78MCQ A mantle plume rises because: A. it is mostly molten B. it is solid but less dense than material around it C. it is molten and more dense than material around it D. it is propelled upward by gas coming out of the magma

Problem 77MCQ A hot spot is interpreted to have formed from: A. extreme heating of the seas near the equator B. abundant magma produced within a subduction zone C. abundant magma formed within a typical mid-ocean ridge D. a rising plume of hot mantle material

Problem 79MCQ Hot spots in continental settings typically produce: A. high continental plateaus, such as in Tibet B. lines or clusters of islands C. basaltic lava flows or explosive calderas D. new oceanic crust

Problem 80MCQ What is typically occurring when magmatism occurs far away from plate boundaries? A. new oceanic crust is created at mid-ocean ridges B. large volcanoes are built above subduction zones C. some type of thermal disturbance is occurring in the mantle D. all of these

Problem 83MCQ Which of the magma systems shown is likely to contain mostly basalt? A. A B. B C. C D. all of the locations E. locations A and B only

Problem 81MCQ At which of the sites shown in this figure would melting probably be caused by introduction of water into hot rocks? A. A B. B C. C D. D E. E

Problem 84MCQ Which of the magma systems shown is most likely to include felsic or intermediate magmas? A. A and B B. B and C C. A, B, and C D. B, C, and D E. C, D, and E

Problem 85MCQ The igneous feature shown in this photograph is: A. dike B. sill C. volcanic neck D. batholith

Problem 82MCQ Which of the sites shown in this figure have decompression melting in an oceanic setting? A. A B. B C. C D. all of the locations shown E. locations A and B only

Problem 86MCQ The igneous feature shown in this figure is a: A. dike B. sill C. volcanic neck D. laccolith

Problem 88MCQ The igneous feature shown in this figure is a: A. dike B. sill C. volcanic neck D. laccolith

Problem 89MCQ The vertical igneous feature shown in this photograph is a: A. dike B. sill C. volcanic neck D. batholith

Problem 90MCQ The dark igneous features shown in this photograph are: A. dikes B. sills C. volcanic necks D. batholiths

Problem 92MCQ The igneous feature shown in this photograph is: A. dike B. sill C. volcanic neck D. batholith

Problem 87MCQ The igneous feature shown in this figure is a: A. dike B. sill C. volcanic neck D. laccolith

Problem 91MCQ The igneous rocks shown in this photograph are forming: A. a dike B. an irregular pluton C. a volcanic neck D. columnar joints

Problem 96MCQ Most igneous rocks in the Sierra Nevada batholith formed from: A. a hot spot beneath continental crust B. continental rifting C. ocean-continent convergence D. transform faulting

Problem 93MCQ A volcanic neck can form by: A. erosion of the volcano, leaving behind the solidified conduit inside the volcano B. erosion of overlying rock layers exposing the conduit below the volcano C. both of these

Problem 94MCQ This figure shows the formation of the Sierra Nevada batholith as magma chambers within the crust. What is the cause of melting? A. melting due to rising solid lithosphere B. decompression melting C. a hot spot D. release of water from the subducting plate

Problem 98MCQ Which of the following is characteristic of the Sierra Nevada? A. peaks and cliffs of gray granite B. a large area of granitic rocks C. metamorphism of rocks within and adjacent to a batholith D. all of these

Problem 97MCQ Which of the following was NOT involved in forming magmas of the main batholith? A. subduction beneath western North America B. water that caused partial melting of hot mantle C. partial melting of continental crust D. solidification of magma below the surface E. recent normal faulting along the east side of the batholith

Problem 95MCQ Which of the following were involved in bringing the deep batholithic rocks to the surface? A. uplift of the rocks over tens of millions of years B. a hot spot that formed a broad continental plateau C. a continent-continent collision with Australia D. the recent restarting of subduction beneath the area

Problem 99MCQ Which of the letters shown on this figure would most likely include some intermediate to felsic magmas? A. B and C B. A and C C. A, B, and C D. B, C, and D E. B, D, and E

Problem 100MCQ Which of the letters shown on this figure would most likely be over magma related to decompression melting? A. A and B B. A, B, and C C. B, C, and D D. C, D, and E E. D and E

Problem 101MCQ Which of the letters shown on this figure would most likely have magmas related to a hot spot? A. A B. B C. A and B D. C E. D and E

Problem 103MCQ Which of the letters shown on this figure would most likely have magma related to subduction? A. A and B B. A and C C. B and D D. D and E E. C and E

Problem 1MCQ Which numbered feature on this figure formed by an explosive pyroclastic eruption? A. Location 1, the Valles Caldera B. Location 2, dark basalt flows along the Rio Grande C. Location 3, the dark, basaltic volcanoes D. Location 4, pegmatite in the northeastern part of the area

Problem 107MCQ For the letters on this figure, choose the likely cause of melting for Site D. A. Decompression melting as the mantle rises B. Melting by adding water C. Melting of continental crust caused by an influx of mantle-derived magmas

Problem 102MCQ Which of the letters shown on this figure would most likely have mafic (basalt) magmas? A. A and B B. A and C C. B and D D. D and E E. C and D

Problem 106MCQ For the letters on this figure, choose the likely cause of melting for Site C. A. Decompression melting as the mantle rises B. Melting by adding water C. Melting of continental crust caused by an influx of mantle-derived magmas