Earth Science Chapter 17 Review

The supercontinent from Wegener's theory of continental drift is called __________ A. Gondwanaland B. Pangaea C. North America D. Laurasia

B. Pangea

What is an isochron? A. a line on a seafloor map that connects points of equal age B. a point on a seafloor map that has a magnetic reversal C. a line on a seafloor map that connects points of equal elevation D. a part of a mid-ocean ridge

A. a line on a seafloor map that connects points of equal age

The map shows where the continents are likely to move in the next 50 million years. The shaded area represents their present position. According to the data on this map, what kind of boundary is found between the Americas and Africa? A. subduction B. divergent C. transform D. convergent

B. divergent

Places where two tectonic plates are moving away from each other are called __________. A. convergent boundaries B. divergent boundaries C. earthquake boundaries D. transform boundaries

B. divergent boundaries

Which mineral may preserve magnetic patterns on the ocean floor which would help support tectonic plates? A. quartz B. magnetite C. feldspar D. mica

B. magnetite

An expedition finds a sample in the rock on the seafloor thought to be 4 million years old. What was the polarity of the Earth at that time, according to the figure? A. nonexistent B. reversed C. normal D. half-reversed

B. reversed

What is the study of Earth's magnetic record? A. magnetometer B. paleogeography C. paleomagnetism D. paleontology

C. paleomagnetism

The thickness of ocean sediments that are close to a mid-ocean ridge is __________ the thickness of ocean sediments that are far from mid-ocean ridges. A. more than B. the same as C. always 100 times D. less than

D. less than

What two topographic features of the ocean floor were discovered only with the use of sonar? A. shallow sea trenches and volcanic islands B. volcanic islands and mid-ocean ridges C. mid-ocean ridges and earthquakes D. mid-ocean ridges and deep sea trenches

D. mid-ocean ridges and deep-sea trenches

When a divergent plate boundary forms on continents, a __________ forms. A. crater B. volcano C. midcontinent ridge D. rift valley

D. rift valley

__________ is a device that can detect changes in the strength of the magnetic field. A. GPS B. Sonar C. Magnetometer D. Satellite

C. Magnetometer

How are the convection currents set in motion? A. slab push and ridge pull B. slab push C. the heat from radioactive decay D. spreading mid-ocean ridges

A. slab push and ridge pull

The __________ states that Earth's crust and ridged upper mantle are broken into plates that move at different rates and in different directions. A. theory of plate tectonics B. hypothesis of continental movement C. theory of seafloor spreading D. hypothesis of continental drift

A. theory of plate tectonics

An expedition brings up a piece of rock from the Gauss normal epoch. According to the figure, what is the probability that it came from a time when the magnetic field is the same as today? A. very likely B. unlikely C. likely D. highly unlikely

A. very likely

What causes the seafloor to spread? A. sinking magma B. rising molten magma C. earthquakes D. drifting continental crust

B. rising molten magma

Where are the youngest rocks on the seafloor located? A. at the mid-ocean ridges B. along the continental shelves C. in the Mariana Trench D. near the Hawaiian Islands

A. at the mid-ocean ridges

The subduction of an oceanic plate beneath a continental plate produces a(n) _________ A. chain of volcanic mountains B. chain of non-volcanic mountains C. inland sea D. rift valley

A. chain of volcanic mountains

The tremendous amount of heat within Earth powers _________ A. plate tectonics B. ocean currents C. weather patterns D. all of the above

A. plate tectonics

Rocks close to mid-ocean ridges are __________ rocks far from mid-ocean ridges. A. younger than B. a different composition than C. older than D. the same age as

A. younger than

What is the process called when one plate is forced beneath another at a convergent plate boundary? A. transformation B. subduction C. convergence D. subtraction

B. subduction

Much of Earth's internal heat comes from ___________________ A. ultraviolet radiation absorbed by rocks B. the decay of radioactive elements C. lightning strikes D. rotation of Earth's core

B. the decay of radioactive elements

According to the data shown in the figure, what was Earth's magnetic polarity like 5 million years ago? A. there was no magnetic field B. the reverse of today C. the same as today D. pointing in an east-west direction

B. the reverse of today

During the time of Pangaea, what had the greatest impact on Earth's climate? A. All the continents were at the equator. B. All the continents were near the poles. C. It was a time of a giant global ocean. D. Temperature varied greatly form the coast of Pangaea to the inner regions.

C. It was a time of a giant global ocean

What is the polarity of a magnetic field that has the same polarity as the present magnetic field? A. an isochron B. a magnetic reversal C. a normal polarity D. a reverse polarity

C. a normal polarity

What is the name of Alfred Wegener's hypothesis about moving landmasses? A. continental movement B. plate tectonics C. continental drift D. seafloor spreading

C. continental drift

Wegener proposed that the continents were __________ A. plowing through oceanic crust B. formed at deep ocean trenches C. formed at midocean ridges D. floating on top of oceanic crust

C. formed at mid-ocean ridges

Harry Hess' theory of __________ explained how ocean crust is generated and destroyed. A. continental drift B. continental movement C. seafloor spreading D. plate tectonics

C. seafloor spreading

A place where two plates slide laterally past each other is called a __________ A. convergent boundary B. mid-ocean ridge C. transform boundary D. divergent boundary

C. transform boundary

Identify the subduction zone in the figure A. A B. C C. B D. D

D. D

What was one reason that Wegener's hypothesis of continental drift was rejected? A. He could not explain what was moving the continents. B. He could not support the idea that climates of certain landmasses had been different . C. He could not support that the continents were once adjacent. D. He could not explain where the continents had moved.

D. He could not explain where the continents had moved

According to the figure, where is an earthquake's focus most likely to occur? A. near the south pole B. in the middle of the Pacific Ocean C. in northern Eurasia D. along the west coast of North America

D. along the west coast of North America

Where do tectonic plates interact? A. at mid-ocean ridges B. in deep sea trenches C. at plate centers D. at plate boundaries

D. at plate boundaries

What is thought to be the driving mechanism of plate movement? A. volcanoes B. conduction of heat in the mantle C. continental drifting D. convection currents in the mantle

D. convection currents in the mantle

What evidence did Wegener use to estimate the time of Pangaea's break up? A. magnetic isochrons B. coal deposits C. ocean floor topography D. fossil data

D. fossil data

Which type of information was NOT collected by Wegener to support his continental drift hypothesis? A. fossils B. seafloor magnetic data C. rocks D. glacial deposits

D. glacial deposits

The geologic features on the ocean floor in this region resulted from _______ A. colliding plates in the lithosphere B. sinking iron and magnesium in the lithosphere C. cooler temperatures in the mantle D. rising convection currents in the magma

D. rising convection currents in the magma