Which of the following is a TRUE statement about the molten (liquid) part of magma? A) during partial melting, it usually has the same composition as the rock from which it was derived; B) it changes composition as the magma cools and partly crystallizes; C) it rarely contains crystals; D) it is mostly sulfide; E) it usually has the same composition as the crystals it is precipitating.
Pressure within the earth _______: A) decreases with depth; B) causes radioactive decay; C) increases as asthenosphere wells up; D) increases with depth; E) does NOT change with depth.
What was a severe hazard at Mt. Pinatubo in 1991? A) ash fall; B) pyroclastic flows; C) mud flows; D) all of the preceding; E) none of the preceding.
Most magmas within the earth are made __________: A) where the crust is thick; B) where asthenosphere is upwelling; C) in plate interiors; D) where the lithosphere is cold; E) by accumulation of olivine.
Explosive volcanic eruptions produce _______ whereas nonexplosive eruptions tend to produce _______: A) lava, mudflows; B) pyroclastic material, lava; C) domes, pyroclastic material; D) lava, domes; E) domes; shields.
A batholith usually consists of many coalesced ________: A) pyroclastic flows; B) pahoehoe flows; C) lahars; D) aa flows; E) none of the preceding.
What is the principal driving force for plate tectonics? A) hotspot convection; B) subduction of oceanic lithosphere; C) pushing at divergent plate boundaries; D) tearing at transform boundaries; E) none of the preceding.
Most divergent plate boundaries lie ________: A) where continents collide; B) at hotspots; C) at mid-ocean ridges; D) at subduction zones; E) at transform faults.
Where do most coarse-grained igneous rocks form? A) in water; B) underground; C) in lava flows; D) in pyroclastic flows; E) in lahars.
About how much more energy does a Richter magnitude 7 earthquake release than a magnitude 5? A) 2 times; B) 140%; C) 10 times; D) 30 times; E) 900 times.
What technique that was NOT used to predict the big eruption of Mt. Pinatubo in 1991? A) geysers erupting from water wells; B) measurement of small earthquakes; C) measurement of gases; D) measurement of the ages of old rocks; E) all of these were used.
The Cascade mountains lie at the type of plate boundary called a _________: A) subduction zone; B) continental collision zone; C) continental rift; D) mid-ocean ridge; E) transform fault.
With decreasing pressure, gases in ascending magma tend to _______: A) freeze; B) exsolve; C) increase in solubility; D) dissolve; E) partially melt.
The following is a mechanism of mechanical weathering: A) frost wedging; B) exfoliation; C) abrasion by streams; D) all of the preceding; E) none of the preceding (they are all chemical weathering).
Clay minerals form principally by weathering of what mineral? A) quartz; B) non-silicate minerals; C) quartz; D) sulfides; E) feldspar.
Earthquake waves arrive at a seismometer in the order: A) compressive-shear-surface; B) shear-compressive-surface; C) compressive-surface-shear; D) surface-shear-compressive; E) shear-surface-compressive.
Which of the following type of extrusive igneous rock is NOT a type of lava: A) a'a; B) ash; C) pahoehoe; D) pillow basalt; E) none of the preceding - they're all lavas.
What is the seismic technique that is used by the petroleum industry, because it is especially useful at imaging horizontally-layered rocks? A) refraction; B) reflection; C) tomography; D) S-wave absorption; E) P-wave absorption.
Sound waves travel through fluids like air, thus they must be _____ waves: A) P; B) S; C) tomographic; D) surface; E) shear.
A comparison of freshwater fossils on Africa and South America reveals that those older than 200,000,000 years are _______ whereas those younger are __________: A) reptiles, mammals; B) mammals, reptiles; C) similar, different; D) different, similar; E) right-side up, upside down.
Hydrolysis refers to: A) the chemical combination of a mineral's atoms with oxygen; B) the displacement of a mineral's atoms by H+; C) the removal of a mineral's atoms by water; D) the substitution of silicon by water; E) adsorption of oxygen onto a mineral's surface.
A giant wave caused by an earthquake is called a: A) seiche; B) lahar; C) P-wave; D) S-wave; E) tsunami.
Which of the following would impart a gravitational force on your body that is greater than that produced by a watermelon 1 meter away? A) A watermelon 2 meters away; B) An ping-pong ball 2 meters away; C) An ping-pong ball 1 meter away; D) A watermelon 0.5 meters away; E) none of the preceding.
How are plate velocities determined? A) GPS; B) Magnetic stripes; C) VLBI; D) Hotspot tracks; E) All of the preceding.
What is the seismic technique used to image 3-dimensional structures deep within the earth? A) refraction; B) reflection; C) tomography; D) S-wave absorption; E) P-wave absorption.
The crust beneath very tall mountains like the Himalayas is especially _______: A) basaltic; B) radioactive; C) thick; D) thin; E) non-radioactive.
The ages of ocean island volcanoes are used to measure the __________ of plates: A) relative motions; B) poleward motions; C) longitudinal motions; D) latitudinal motions; E) absolute motions.
If you had to find a very old rock, where would be the best place to look? A) near the mid-Atlantic ridge; B) in Iceland; C) off the New Jersey coast; D) in the middle of Africa; E) on the floor of the Pacific Ocean.
A piece of evidence that Wegener did NOT know about when he formed his theory of continental drift was: A) paleomagnetism; B) fossils; C) rocks formed by ancient glaciers; D) the fit of the continents; E) all of the preceding.
When seismic waves encounter rocks that transmit the waves at a different velocity, they are bent, which is called _______: A) refraction; B) gravimetry; C) tomography; D) S-wave absorption; E) P-wave absorption.
Some earthquakes cause water-saturated sediment to lose all of its strength, a process called ________: A) rock fall; B) seiche; C) tsunami; D) consolidation; E) liquefaction.
How do we know that the earth's outer core is liquid? A) S-waves do not pass through it; B) plate tectonics; C) the existence of the magnetic field; D) A and C; E) A and B.
"Wallace's line" in Indonesia separates ________: A) a subduction zone from a mid-ocean ridge; B) two mid-ocean ridge segments; C) two areas with different life forms that have been brought together by plate tectonics; D) two areas with different types of volcanoes that have been brought together by plate tectonics; E) none of the preceding - Wallace's line is in the East African rift.
Coal, which contains fossils of tropical plants, exists in Antarctica because ________: A) the earth used to be much warmer; B) plate tectonics moved Antarctica to the south; C) the earth's magnetic poles reversed; D) transform faults tend to make the climate warmer; E) active volcanoes in Antarctica were unusually active.
What type of rocks form the youngest pre-1991 deposits near the summit of Mt. Pinatubo? A) thick pyroclastic flows; B) thin pahoehoe lavas; C) pillow basalts; D) granite batholiths; E) granite plutons.
What is the minimum number of seismometers needed to locate the epicenter of an earthquake? A) 1; B) 2; C) 3; D) 5; E) the question is misleading: the epicenter is determined with a gravimeter.
The map above shows the magnetic stripes around a mid-ocean ridge. What is the direction of relative plate motion of the Hoover plate? A) north; B) south; C) east; D) west; E) you can't tell without a hotspot track.
The most recent switch of the earth's magnetic poles was about 700,000 years ago. Roughly, what is the velocity of the Pitcher plate relative to the ridge? A) 30 meters/year; B) 3 meters/year; C) 10 centimeters/year; D) 3 centimeters/year; E) 3 millimeters/year.
The Hoover and Pitcher Plates must have similar relative velocities because ______ : A) the lengths of the transforms are similar; B) the magnetic stripes are offset; C) the ridge is oriented nearly east-west; D) the magnetic stripes are the same width on either side of the ridge; E)
What type of rock would likely be found on the Hoover plate near the ridge? A) granite; B) rhyolite; C) basalt; D) andesite; E) sandstone.
