EAPS 106 - EXAM 1 QUESTIONS AND
ANSWERS
What is a solar nebula? - Correct Answers -a disc of gas and dust surrounding all new
stars
Why are new planets hot inside? - Correct Answers -planetary accretion produces heat
due to collisions; the decay of radioactive elements under the surface
What is a rogue planet? - Correct Answers -a planet that does not orbit a star (likely due
to ejection from its parent solar system)
What are the layers of the Earth? - Correct Answers -crust, mantle, outer core (liquid),
inner core
Why is the Earth layered? - Correct Answers -differences in density: more dense layers
sink below less dense ones (called differentiation)
Why is the inner core solid despite being hotter than the outer core? - Correct Answers -
the inner core is under higher pressure than the outer core
What is the lithosphere? - Correct Answers -the rigid outer part of the earth, consisting
of the crust and upper mantle
What is the asthenosphere? - Correct Answers -an upper layer of the Earth's mantle
weakened by high temperatures that flows (like a liquid)
What is plate tectonics? - Correct Answers -the motion of large plates of the lithosphere
gliding on top of the asthenosphere
Why does the mantle below the asthenosphere not flow easily? - Correct Answers -it is
at higher pressure than the asthenosphere
What is the evidence for continental drift (3 reasons)? - Correct Answers -North and
South American coastlines fit with Europe and Africa; identical volcanic rocks appeared
on opposite sides of the Atlantic ocean; fossils of non-swimmers found on both sides of
modern oceans
, Why did scientists initially reject continental drift? - Correct Answers -the strong, rigid
crust would have to get out of the way; it wasn't obvious what tremendous force would
cause them to move
What is a magnetic reversal? - Correct Answers -when Earth's magnetic poles change
places
How do we know the magnetic poles reverse? - Correct Answers -alternating patterns in
the magnetic polarity of volcanic rock
What breakthrough observation led to the theory of plate tectonics? - Correct Answers -
magnetic reversals found in ocean rocks which enabled the determination of the age of
the ocean crust and that it had spread out from spreading centers
What is a mid-ocean ridge? - Correct Answers -mid-ocean ridges are spreading centers
where new ocean crust forms and spreads apart
What is the relative age of the ocean crust compared to the continental crust? - Correct
Answers -ocean crust is much younger (0-200 million years) than the continental crust
(> 1 billion years)
What is a subduction zone? - Correct Answers -where one plate goes under (subducts
under) another plate and part of its crust is destroyed in the mantle
What is a transform boundary? - Correct Answers -where two plates slide past each
other
What type of boundary is the San Andreas Fault? - Correct Answers -transform
boundary
What is a passive margin? - Correct Answers -a boundary between continental and
oceanic crust where there is no relative motion and no major geological activity (it is
where the continents initially separated)
Does Hawaii lie on a plate boundary? - Correct Answers -no (it does not lie anywhere
near one)
How are earthquakes triggered? - Correct Answers -the sudden and rapid release of
stress built up on areas of weaker crust (such as fault lines)
What is a supercontinent? - Correct Answers -a large continent made up of most
modern day continents broken apart by tectonic activity
What building collapses were most problematic during the Wenchuan earthquake? -
Correct Answers -the collapse of 7,000 poorly built schoolhouses called tofu-dreg
schoolhouses which killed 10,000 students
ANSWERS
What is a solar nebula? - Correct Answers -a disc of gas and dust surrounding all new
stars
Why are new planets hot inside? - Correct Answers -planetary accretion produces heat
due to collisions; the decay of radioactive elements under the surface
What is a rogue planet? - Correct Answers -a planet that does not orbit a star (likely due
to ejection from its parent solar system)
What are the layers of the Earth? - Correct Answers -crust, mantle, outer core (liquid),
inner core
Why is the Earth layered? - Correct Answers -differences in density: more dense layers
sink below less dense ones (called differentiation)
Why is the inner core solid despite being hotter than the outer core? - Correct Answers -
the inner core is under higher pressure than the outer core
What is the lithosphere? - Correct Answers -the rigid outer part of the earth, consisting
of the crust and upper mantle
What is the asthenosphere? - Correct Answers -an upper layer of the Earth's mantle
weakened by high temperatures that flows (like a liquid)
What is plate tectonics? - Correct Answers -the motion of large plates of the lithosphere
gliding on top of the asthenosphere
Why does the mantle below the asthenosphere not flow easily? - Correct Answers -it is
at higher pressure than the asthenosphere
What is the evidence for continental drift (3 reasons)? - Correct Answers -North and
South American coastlines fit with Europe and Africa; identical volcanic rocks appeared
on opposite sides of the Atlantic ocean; fossils of non-swimmers found on both sides of
modern oceans
, Why did scientists initially reject continental drift? - Correct Answers -the strong, rigid
crust would have to get out of the way; it wasn't obvious what tremendous force would
cause them to move
What is a magnetic reversal? - Correct Answers -when Earth's magnetic poles change
places
How do we know the magnetic poles reverse? - Correct Answers -alternating patterns in
the magnetic polarity of volcanic rock
What breakthrough observation led to the theory of plate tectonics? - Correct Answers -
magnetic reversals found in ocean rocks which enabled the determination of the age of
the ocean crust and that it had spread out from spreading centers
What is a mid-ocean ridge? - Correct Answers -mid-ocean ridges are spreading centers
where new ocean crust forms and spreads apart
What is the relative age of the ocean crust compared to the continental crust? - Correct
Answers -ocean crust is much younger (0-200 million years) than the continental crust
(> 1 billion years)
What is a subduction zone? - Correct Answers -where one plate goes under (subducts
under) another plate and part of its crust is destroyed in the mantle
What is a transform boundary? - Correct Answers -where two plates slide past each
other
What type of boundary is the San Andreas Fault? - Correct Answers -transform
boundary
What is a passive margin? - Correct Answers -a boundary between continental and
oceanic crust where there is no relative motion and no major geological activity (it is
where the continents initially separated)
Does Hawaii lie on a plate boundary? - Correct Answers -no (it does not lie anywhere
near one)
How are earthquakes triggered? - Correct Answers -the sudden and rapid release of
stress built up on areas of weaker crust (such as fault lines)
What is a supercontinent? - Correct Answers -a large continent made up of most
modern day continents broken apart by tectonic activity
What building collapses were most problematic during the Wenchuan earthquake? -
Correct Answers -the collapse of 7,000 poorly built schoolhouses called tofu-dreg
schoolhouses which killed 10,000 students
