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
