EarthÝs Dynamic Interior, 2003.  For answers, click here

Quiz #1 

1) What type of rock is shown on the screen?

a) Igneous intrusive

b) Igneous extrusive

          c) Metamorphic

d) Sedimentary

2) What type of rock is shown on the screen?

a) Igneous intrusive

b) Igneous extrusive

c) Metamorphic

d) Sedimentary

3) Which one of these statements about lava and magma is true?

a) Lava is liquid rock at the earthÝs surface; magma is the fine-grained part of the rock.

b) Lava is liquid rock at the earthÝs surface; magma is liquid rock beneath the earthÝs surface.

c) Lava is liquid rock at the earthÝs surface; magma is violently ejected material from a volcano.

d) Lava is liquid rock at earthÝs surface; magma is any type of crystalline rock, incl metamorphic.

e) Lava is liquid rock at the earthÝs surface; magma is intrusive rock that has been exposed byerosion.

4) The presence of phenocrysts in volcanic rocks indicates

a) Partial melting at the transition of metamorphic to igneous processes.

b) Partial crystallization after cooling of the rock.

           c) Partial crystallization before eruption.

d) Addition of extra silica to the magma.

e) Phenocrysts donÝt exist in volcanic rocks.

5) Which of the following igneous rocks is compositionally similar to granite?

a) basalt

b) peridotite

c) gabbro

d) andesite

e) rhyolite

6) The two most abundant elements in the earthÝs crust are

a) iron and magnesium

b) iron and oxygen

c) iron and silicon

d) oxygen and silicon

e) quartz and feldspar

7) The two most abundant elements in the whole earth are

a) iron and magnesium

b) iron and oxygen

c) iron and silicon

d) oxygen and silicon

e) olivine and pyroxene

8) The Moho is

a) the boundary between the crust and the mantle

b) the boundary between the oceanic and continental crust

c) the boundary between the lithosphere and the asthenosphere

d) the boundary between the core and the mantle

e) none of the above. 

9) Evidence that the asthenosphere is partially melted comes from seismic waves.Which of the following statements is true?

a) Velocity of P waves increases when entering the asthenosphere while S waves decrease.

b) Velocity of P waves and S waves both decrease when entering the asthenosphere.

c) Velocity of P waves and S waves both increase when entering the asthenosphere.

d) Velocity of P waves decreases when entering the asthenosphere while S waves increase.

e) P waves stop.

10) The lithosphere

a) consists of the lower mantle and transitional zone.

b) corresponds to the continental crust.

 c) corresponds to the oceanic crust.

d) consists of the continental and oceanic crust.

e) consists of the crust and upper mantle.

11) The mineral Potassium feldspar is an important common component of granite.It has the chemical formula KalSi308.In which class does it belong?

a) silicates

b) carbonates

c) sulfates

d) sulfides

e) oxides

12) Igneous rocks form at which of these plate tectonic settings?

a) convergent ­collisional

b) convergent ­subduction zones

c) divergent

d) b and c

e) all of the above

13) An ultramafic igneous rock isÍ

a) one in which silica content is less than about 50%

          b) one in which silica content is more than about 50%

c) an intrusive mafic rock

d) an extrusive mafic rock

e) a volcanic rock that is expelled violently during an eruption.

14) Viscosity plays an important role in volcanic activity because

a) higher viscosity magmas tend to be less explosive.

b) higher viscosity magmas tend to produce steeper volcanoes.

c) higher viscosity magmas tend to produce rocks of greater density.

d) b and c

e) a, b, and c

15) Volcanoes form above subduction zones because

a) the descending oceanic plate melts to produce magma.

b) the descending continental plate melts to produce magma.

c) the inward plate motion thrusts rocks skyward.

d) the descending plate heats and releases water, which causes melting in the overriding plate.

e) the descending plate heats up, which in turns heats the overriding plate to cause melting.