EAPS 106 - EXAM 1 QUESTIONS WITH
CORRECT ANSWERS
Know Earth's four layers and their approximate relative thicknesses. - Correct Answers -
Crust (6371 km), Mantle (6336 km), Outer Core (3486 km), Inner Core (1216 km)
How the Earth acquired its internal heat. - Correct Answers -planetary accretion: Heat of
collisions plus radioactive decay leads new planets to be molten (melted) inside,
Know why the interior of the Earth is layered. - Correct Answers -planetary accretion:
Heat of collisions plus radioactive decay leads new planets to be molten (melted) inside,
which leads to differentiation as heavier elements sink to form a core and lighter
elements rise to form a crust and mantle.
Why the outer core is a liquid, but the hotter inner core is solid - Correct Answers -
Because the inner core is under more pressure
What lithosphere and asthenosphere are - Correct Answers -Lithosphere: Strong outer
shell of the Earth consisting of the crust and uppermost (coldest, strongest) layer of the
mantle. (breaking = tectonic plates)
Asthenosphere: Weakest layer of the mantle (flows readily) and underlies the
lithosphere. (allows tectonic plates to move, silly putty)
Know the evidence that Wegner used to suggest that the continents drift - Correct
Answers -North and South America coastlines fit with Europe and Africa, Identical
volcanic flows appear on both sides of the Atlantic, Fossils of non-swimmers found on
both sides of the modern oceans
How we know that our magnetic field has reversed itself many times - Correct Answers -
In the 1960s, we discovered magnetic lineations on the seafloor that reveal how ocean
crust is created at and then moves away from "spreading centers" (also called mid-
ocean ridges).
Crystals in lava record the direction to the magnetic poles at the time of each eruption.
What a mid-ocean ridge, a subduction zone, and a transform plate boundary are -
Correct Answers -Mid-Ocean Ridges: referred to as divergent margins since the plates
move away each other
Subduction Zone: Oceanic lithosphere is recycled back into the mantle at "subduction
zones", which enables continents to drift over the ocean basins
referred to as convergent margins since the plates move toward each other, where most
earthquakes and volcanoes occur.
, Transform Plate Boundary: where two plates laterally slide past each other.
What a passive plate margin is - Correct Answers -a boundary between continental
crust and oceanic crust that is not a plate boundary
What a supercontinent is - Correct Answers -one big continent with most or all of the
land mass
What caused the high topography of the Himalayas and Tibet - Correct Answers -India
colliding into Asia during continental drift and creating the tallest mountains in the world
(only time two continents collided)
What the Wilson cycle is - Correct Answers -The Wilson Cycle is describes how
continents break up and then rejoin
How plate tectonics can influence evolution (particularly whales and dolphins) - Correct
Answers -The evolution of dolphins and whales appears tied to the shallowing of the
Tethys Sea when India first collided into Asia
Whether convection can occur within a crystalline solid - Correct Answers -Earth's
mantle is a solid (it has a crystalline
structure), but deforms like a fluid on short
timescales, it thus transfers heat through
convection. This is called solid-state convection
What earthquake intensity (Mercalli Scale) measures and the factors that influence it -
Correct Answers -Mercalli Intensities: The shaking that people and buildings feel. Based
on felt reports.
Influenced by the magnitude of an earthquake, its
distance, and the local geology
Why the US Geological Survey believes there is a high seismic hazard in the midwest -
Correct Answers -Three of the largest earthquakes to occur in the contiguous U.S.
happened in the midwest.
Why earthquakes are felt farther away in the eastern US compared to the western US -
Correct Answers -The crust is more broken up in the west because it is a plate
boundary so earthquakes aren't as strong compared to the midwest where its all
compacted
The relationship between the biggest magnitude earthquakes and the deadliest -
Correct Answers -The biggest earthquakes (M8+) are not generally the deadliest — it is
often M7+ that occur in heavily populated regions with poor building practices.
What drives plate tectonics - Correct Answers -Convection in the Earth's solid-state
mantle drives plate tectonics (bottom surface is hot and top surface is cold)
CORRECT ANSWERS
Know Earth's four layers and their approximate relative thicknesses. - Correct Answers -
Crust (6371 km), Mantle (6336 km), Outer Core (3486 km), Inner Core (1216 km)
How the Earth acquired its internal heat. - Correct Answers -planetary accretion: Heat of
collisions plus radioactive decay leads new planets to be molten (melted) inside,
Know why the interior of the Earth is layered. - Correct Answers -planetary accretion:
Heat of collisions plus radioactive decay leads new planets to be molten (melted) inside,
which leads to differentiation as heavier elements sink to form a core and lighter
elements rise to form a crust and mantle.
Why the outer core is a liquid, but the hotter inner core is solid - Correct Answers -
Because the inner core is under more pressure
What lithosphere and asthenosphere are - Correct Answers -Lithosphere: Strong outer
shell of the Earth consisting of the crust and uppermost (coldest, strongest) layer of the
mantle. (breaking = tectonic plates)
Asthenosphere: Weakest layer of the mantle (flows readily) and underlies the
lithosphere. (allows tectonic plates to move, silly putty)
Know the evidence that Wegner used to suggest that the continents drift - Correct
Answers -North and South America coastlines fit with Europe and Africa, Identical
volcanic flows appear on both sides of the Atlantic, Fossils of non-swimmers found on
both sides of the modern oceans
How we know that our magnetic field has reversed itself many times - Correct Answers -
In the 1960s, we discovered magnetic lineations on the seafloor that reveal how ocean
crust is created at and then moves away from "spreading centers" (also called mid-
ocean ridges).
Crystals in lava record the direction to the magnetic poles at the time of each eruption.
What a mid-ocean ridge, a subduction zone, and a transform plate boundary are -
Correct Answers -Mid-Ocean Ridges: referred to as divergent margins since the plates
move away each other
Subduction Zone: Oceanic lithosphere is recycled back into the mantle at "subduction
zones", which enables continents to drift over the ocean basins
referred to as convergent margins since the plates move toward each other, where most
earthquakes and volcanoes occur.
, Transform Plate Boundary: where two plates laterally slide past each other.
What a passive plate margin is - Correct Answers -a boundary between continental
crust and oceanic crust that is not a plate boundary
What a supercontinent is - Correct Answers -one big continent with most or all of the
land mass
What caused the high topography of the Himalayas and Tibet - Correct Answers -India
colliding into Asia during continental drift and creating the tallest mountains in the world
(only time two continents collided)
What the Wilson cycle is - Correct Answers -The Wilson Cycle is describes how
continents break up and then rejoin
How plate tectonics can influence evolution (particularly whales and dolphins) - Correct
Answers -The evolution of dolphins and whales appears tied to the shallowing of the
Tethys Sea when India first collided into Asia
Whether convection can occur within a crystalline solid - Correct Answers -Earth's
mantle is a solid (it has a crystalline
structure), but deforms like a fluid on short
timescales, it thus transfers heat through
convection. This is called solid-state convection
What earthquake intensity (Mercalli Scale) measures and the factors that influence it -
Correct Answers -Mercalli Intensities: The shaking that people and buildings feel. Based
on felt reports.
Influenced by the magnitude of an earthquake, its
distance, and the local geology
Why the US Geological Survey believes there is a high seismic hazard in the midwest -
Correct Answers -Three of the largest earthquakes to occur in the contiguous U.S.
happened in the midwest.
Why earthquakes are felt farther away in the eastern US compared to the western US -
Correct Answers -The crust is more broken up in the west because it is a plate
boundary so earthquakes aren't as strong compared to the midwest where its all
compacted
The relationship between the biggest magnitude earthquakes and the deadliest -
Correct Answers -The biggest earthquakes (M8+) are not generally the deadliest — it is
often M7+ that occur in heavily populated regions with poor building practices.
What drives plate tectonics - Correct Answers -Convection in the Earth's solid-state
mantle drives plate tectonics (bottom surface is hot and top surface is cold)
