Chapter 2. Internal Energy and Plate Tectonics Questions

____ in the mantle form when hot mantle material rises, moves laterally, and then sinks when it becomes cold. (Enter only one word per blank.)

Convection cells

True or false: The best fit of the continents to form Pangaea occurs when you match the shorelines.

False

True or false: The oldest Solar System materials are approximately 4.57 billion years old, the same age as Earth.

False

The edges of the tectonic plates can easily be defined by mapping the locations of

earthquakes

The oldest Earth material, dated at 4.37 billion years old, is a(n) ______.

grain of zircon from Australia

As Earth pulled into a dense mass during its early formation and then differentiated into layers of different density, ______ energy was released.

gravitational

Impacts, radioactive decay, gravity, and differentiation all provided ___ which transformed early Earth.

heat

A ____ is a place on Earth where a plume of magma has risen up from the mantle and through a plate to reach the surface. (Enter only one word per blank.)

hot;spot

The four outer planets of the Solar System are mostly composed of ______.

hydrogen, helium, and other frozen materials

The heat produced by masses colliding to form Earth is referred to as ______ energy.

impact

Water depths ___ systematically with seafloor age

increase

The continents make up approximately _____ of Earth's total volume.

0.1%

Geologic studies suggest that the outer layers of Earth were active in the process of plate tectonics by at least _____ billion years ago.

1.5

The oldest rocks on the ocean floors are approximately _______ years old.

200 million

It is likely that oceans and small continents existed on Earth by ____ billion years ago and that life was present by ____ billion years ago.

4.4; 3.5

Earth appears to have begun as an aggregating mass of particles and gases about ____ years ago.

4.6 billion

Examine this figure. Assuming there are 5000 atoms, of the parent isotope, how many would remain after three half-lives?

625

Examine this figure, which shows the breakup of Pangaea into two supercontinents separated by a sea. Match the letters A, B, C with the correct labels.

A: Laurasia B: Tethys C: Gondwanaland

Match the upper layers of Earth to their correct locations.

Continental crust Mantle Lithosphere Asthenosphere

Where are the oldest seafloor rocks found?

At the edges of ocean basins

Which of these is an example of a volcanic continental arc formed when an oceanic plate is subducted beneath a continental plate?

Cascade Range

Why is it difficult to study the early history of the Earth?

Early Earth rocks are difficult to find due to plate tectonics.

The most current hypothesis for how the Moon was formed would suggest that it is mostly made up of material from ______.

Earth's mantle

True or false: The Earth formed its compositional layers (core, mantle, crust, atmosphere) by accretion in stages: first iron-rich materials, followed by rocky materials, and finally by ices.

False

Which of the following are consequences of collisions of large objects during the formation of the Solar System? (Select all that apply.)

Formation of even larger objects Melting of rock Loss of volatiles to space

What led James Hutton to propose the the Earth must be extremely old?

He noted that natural processes, such as erosion, were very slow.

Which of the following astronomers introduced the most widely accepted hypothesis regarding the origin of the Solar System?

Immanuel Kant in 1755

Which of the following are sources of heat generated during the formation of Earth? (Check all that apply.)

Impact energy Gravitational energy Differentiation into layers Radioactive decay

Which of these has the lowest density?

Oceans

Which of the following was the only process to occur during the last 65 million years?

India rammed into Asia.

Why are sequences of layered lava flows, such as the one shown here, so useful in the construction of the timescale of magnetic reversals? (Select all that apply.)

Lavas contain radioactive elements that can be used to date them. Lavas become magnetized as they cool below the Curie point.

______ is the reaction in which two or more atomic nuclei collide and join to form a new type element.

Nuclear fusion

Which of these are features that form when an oceanic plate subducts beneath a continental plate? (Select all that apply.)

Oceanic trench Volcanic continental arc

Why do ocean water depths increase away from the midocean ridges? (Check all that apply.)

Older oceanic crust is denser and thus sits lower on the asthenosphere. The accumulation of sediments over time adds weight to the seafloor.

What is the name of the process marked with the letter A on this diagram?

Seafloor spreading

______ is the effect of a down-going plate at a subduction zone on the lateral motion of the plates.

Slab pull

______ is the force per unit area applied to an object.

Stress

What kind of plate boundary is most commonly associated with deep earthquakes?

Subduction zone

According to this image, which of the following statements about the age of the seafloor are correct? (Select all that apply.)

The seafloor gets progressively older away from the midocean ridges. The youngest oceanic rocks are found at the midocean ridges. The oldest rocks of the seafloor are approximately 180 million years old.

What feature forms when one oceanic plate subducts beneath another?

Volcanic ocean arc

Where are the deepest parts of the ocean found?

Where the seafloor is oldest

The lateral movement of the tectonic plates occurs as they ride along on top of ______ in the mantle.

convection cells

The Aleutian Islands of Alaska are an example of a volcanic island arc that forms when _______.

an oceanic plate subducts beneath another oceanic plate

The ___ is the part of the upper mantle that behaves in a plastic, mechanically weak manner.

asthenosphere

A precursor to the theory of plate tectonics, ______ was proposed by Alfred Wegener in 1915. (Enter only one word per blank.)

continental drift

The flow of energy from Earth's interior has its source in radioactive ___, gravitational energy, and ___ energy

decay; impact

The three types of strain (deformation) are ____, ____, and ____. (Enter only one word per blank.)

elastic; plastic; brittle

The breakthrough that led to the development of the theory of plate tectonics was the _______.

exploration of the ocean floors

Compared to continental rocks, some of which are more than 4 billion years old, the rocks of the ocean floor are _______.

extremely young

Liquids and gases are both considered to be

fluid

This image demonstrates the principle of ______.

isotasy

The widths of magnetized seafloor stripes correlate well with the ________ reversals of Earth's magnetic field.

lengths of time between

Hydrogen and helium, the two main constituents of the Sun, are both ______ elements.

lightweight

The tectonic plates are made up of the _________.

lithosphere

The ______ rides upon the ______ and is composed of both the ______ and the uppermost ______.

lithosphere; asthenosphere; crust; mantle

The deepest parts of the oceans occur in elongate narrow trenches that are associated with ______.

subduction zones

The ______ formed through collisions of particles that fused together, forming larger objects.

planets

Examine this figure. If you measure the width of one of the magnetic stripes and you know the ages of the magnetic reversals, then you can calculate the ________.

rate of seafloor spreading

The four inner planets of the Solar System are mostly composed of ______.

rocky material

The paleomagnetic timescale and the patterns of magnetism on the seafloor provide compelling evidence for ______.

seafloor spreading

The continental crust was formed by _________.

separation of low-density elements from the mantle

Earth's core, which is composed mostly of iron, is divided into the ____ inner core and the ____ outer core.

solid; liquid

The great mountain ranges that extend more than 65,000 km across the ocean bottoms are formed at _________.

spreading centers

The lithosphere, asthenosphere, mesosphere, outer core, and inner core are layers of Earth that are distinguished from one another by their _______.

strengths

Earthquakes that occur along inclined planes adjacent to deep-ocean trenches are evidence for _______.

subduction

The movement of molten iron inward to form Earth's core resulted in __________.

the release of gravitational energy, which converted to heat

According to plate tectonic theory, the initiation of a rift zone is caused by _______.

the rise of hot mantle material toward the Earth's surface

Away from the oceanic ridges the layer of sediment covering the seafloor becomes ______.

thicker