
Scientific data suggest that the age of the Earth is about
A.  100 million years. 
B.  650 million years. 
C.  3.5 billion years. 
D.  4.6 billion years. 
ANSWER: D

Which of the following statements about the ocean is false?
A.  It covers about 71 percent of the Earths surface. 
B.  It holds about 80 percent of the Earths water. 
C.  Its average temperature is about 4 degrees C (39 degrees F). 
D.  Its average depth is about 3800 meters (12,500 feet). 
ANSWER: B

A scientific theory is
A.  the same thing as scientific speculation. 
B.  a proposed idea not yet supported by much convincing observation or experimentation.
C.  supported by a good deal of evidence and is widely accepted. 
D.  one of many contradictory explanations of a natural phenomenon. 
ANSWER: C

A test of a hypothesis is called 
A.  a variable. 
B.  an experiment. 
C.  a model. 
D.  a theory. 
ANSWER: B

Which of the following lists of elements represents the main components of the Earths crust?
A.  hydrogen, uranium, thorium 
B.  oxygen, silicon, uranium 
C.  oxygen, silicon, aluminum 
D.  iron, aluminum, carbon 
E.  iron, hydrogen, nitrogen  
ANSWER: C

Oceanic crust is
A.  composed primarily of basalt rock. 
B.  similar in composition and features to continental crust. 
C.  covered everywhere with thick layers of sedimentary rock. 
D.  composed of granite layers extending deep into the Earths mantle. 
ANSWER: A

The principal force driving the lithospheric plates is believed to be
A.  magnetism. 
B.  polarity. 
C.  the pull of the sun and the moon. 
D.  deep water currents pulling on the ocean basins. 
E.  convection cells in the upper mantle. 
ANSWER: E

The magnetic striping of the seafloor is considered evidence of seafloor spreading and 
A.  subduction down the rift valleys. 
B.  spreading centers in the trenches. 
C.  changes in the Earths axis of rotation. 
D.  periodic reversals in the polarity of the Earths magnetic field. 
E.  periodic collapses of the Earths gravitational field. 
ANSWER: D

New crust is being generated
A.  in the deep trenches. 
B.  in submarine canyons. 
C.  in the rift valleys of mid-ocean ridges. 
D.  at the centers of large continents. 
E.  in all of these places. 
ANSWER: C

The speed at which most plates move is about
A.  3 kilometers per hour. 
B.  3 kilometers per thousand years. 
C.  3 centimeters per hour. 
D.  3 centimeters per year. 
E.  3 centimeters per million years. 
ANSWER: D

Continental crust is _____ than oceanic crust.
A.  thinner and denser 
B.  thinner and less dense 
C.  thicker and denser 
D.  thicker and less dense 
ANSWER: D

The oldest rocks of the continents are over 3 billion years old, while the oldest rocks from the seafloor are only about 200 million years old.  This is because
A.  the breakup of Panthalassa has destroyed all ancient seafloor. 
B.  the continents are remnants of ancient mantle before the crust hardened. 
C.  all the older seafloor exists as a basal layer under present conditions. 
D.  new seafloor eventually subducts in deep-sea trenches, which is a process that usually takes place in less than 200 million years. 
ANSWER: D

Land-based evidence for plate tectonics can be seen in
A.  the distribution of the Glossopteris flora. 
B.  evidence of ancient glaciation. 
C.  the lineation of mountain ranges. 
D.  the correlation of rocks in now widely separated continents. 
E.  all of the above 
ANSWER: E

The Earths lithosphere consists of the
A.  mantle and the core. 
B.  uppermost mantle and the crust. 
C.  lowermost asthenosphere. 
D.  mesosphere and the asthenosphere. 
ANSWER: B

Which of the following statements about subduction zones is true?
A.  They have active volcanism and produce new seafloor. 
B.  They are located adjacent to mid-ocean ridges. 
C.  They are associated with belts of deep-focus earthquakes. 
D.  Their tectonic activity is caused by plumes and magma rising from the deep mantle.  
ANSWER: C

The zone of earthquakes found along the region where one plate subducts under another is called a
A.  Wadati-Benioff zone. 
B.  Richter zone. 
C.  liquefaction zone. 
D.  fracture zone. 
ANSWER: A

Convergent plate boundaries are zones where
A.  plates are subducted or collide. 
B.  plates are subducted or shifted sideways by transform faulting. 
C.  plates are rifted and shifted sideways. 
D.  mid-ocean ridges and trenches form. 
E.  plates are compressed and shifted sideways. 
ANSWER: A

The movement of the Pacific Plate past the North American Plate along the San Andreas fault is an example of this type of plate boundary:
A.  continent-continent collision. 
B.  ocean-continent collision. 
C.  divergent. 
D.  transform fault. 
ANSWER: D

Which of these was formed by a convergence of two continental plates?
A.  Himalaya Mountains 
B.  Marianas trench 
C.  Aleutian Islands 
D.  Chesapeake Bay 
ANSWER: A

The Atlantic ocean
A.  is currently shrinking in size. 
B.  has been widening for millions of years. 
C.  is widening between Africa and South America and narrowing between Europe and North America. 
D.  is widening between Europe and North America and narrowing between Africa and South America. 
ANSWER: B








