The Earth's Interior Flashcards
Why are there no P-waves or S-waves received in the P-wave shadow zone?
P-waves are refracted and S-waves are absorbed by Earth’s outer core.
What makes up the lithosphere?
Crust and the upper mantle
Miners dig into the Earth in search for precious rocks and minerals. In which layer is the deepest explorations made by miners?
Crust
How do you compare the densities of the Earth’s crust, mantle, and core?
The mantle is less dense than the core but denser than the crust.
The movement of the lithospheric plates is facilitated by a soft, weak and plastic-like layer. Which of the following layers is described in the statement?
Asthenosphere
Alfred Wegener is a German scientist who hypothesized that the Earth was once made up of a single large landmass called Pangaea. Which of the following theories did Wegener propose?
Continental Drift Theory
If you are a cartographer, what will give you an idea that the continents were once joined?
Shapes of the continents
Which observation was NOT instrumental in formulating the hypothesis of seafloor spreading?
Identifying the location of glacial deposits
As a new seafloor is formed at the mid-ocean ridge, the old seafloor farthest from the ridge is destroyed. Which of the stated processes describes how the oceanic crust plunges into the Earth and destroyed at the mantle?
Subduction
What are the different layers of the Earth?
Crust
Mantle
Core
In 1912, Alfred Wegener proposed a theory that the Earth is once a single landmass. What is the name of the Mesozoic supercontinent that consisted of all of the present continents?
Pangaea
Who were the two scientists who proposed the theory of seafloor spreading in the early 1960s?
Harry Hess and Robert Dietz
During the 1960s, scientists were already equipped with gadgets needed to explore the deep ocean. What discovery about the ocean floor is associated with the seafloor spreading?
The crust of the ocean is very young relative to the age of the crust
of the continents.
If the Atlantic Ocean is widening at a rate of 3 cm per year, how far (in kilometers) will it spread in a million years?
30 kilometers
Which of the following increases with distance from a mid-ocean ridge?
a. the age of oceanic lithosphere
b. the thickness of the lithosphere
c. the depth to the sea floor
Which of the following can you infer from the continuous movement of the lithospheric plates over the asthenosphere?
The continents will not be located in the same place as they are now.
If all the inner layers of the Earth are firm solid, what could have happened to Pangaea?
It remained as a supercontinent.
Why does the oceanic crust sink beneath the continental crust at the subduction zone?
The oceanic crust is pushed from the ridge.
The lithospheric plates are believed to be moving slowly. What is the driving force that facilitates this movement?
convection current in the mantle
The _____ is the middle layer of the Earth. It makes most of the Earth’s
volume and mass.
mantle
The _______ is made up of molten material and accounts for the Earth’s magnetic field.
outer core
The _______ is the deepest layer of the Earth. It is made up of solid nickel and iron. The temperature in the inner core reaches as high as 5000oC
inner core
properties of seismic waves are used by scientists to study the structure and composition of the Earth’s interior.
Speed
Refraction
Reflection
The ___________ of Alfred Wegener states that the continents were once part of a large landmass called Pangaea which drifted away from each other. The continents moved away from each other towards their current positions.
Continental Drift Theory
_____________ is believed to occur as hot magma rises at the rift in the mid-ocean ridge. This magma cools down and becomes the new seafloor as it pushes the former.
Seafloor spreading
The ___________ is destroyed at the subduction zone and melts inside the mantle.
old seafloor
The _________________ in the ocean floor support the Seafloor Spreading Theory.
age of rocks
magnetic stripes
The ______________ helps explain the formation and destruction of the Earth’s crust and its movement over time.
Theory of Plate Tectonics
Scientists believe that the plates’ movement is due to ___________ in the mantle.
convection currents
soft, weak upper portion of the mantle where the lithospheric plates float and move around
Asthenosphere
states that all the continents were once one large landmass that broke apart, and where the pieces moved slowly to their current locations
Continental Drift Theory
current in the mantle because of the heat from the inner layers of the Earth, and is the force that drives the plates to move around
Convection Current
the topmost, solid part of the Earth that is composed of several plates
Litosphere
the moving, irregularly-shaped slabs that fit together to form the surface of the Earth
Lithospheric plates
area in the middle of the ocean where a new ocean floor is formed when lava erupts through the cracks in the Earth’s crust
Mid ocean ridge
the boundary that separates the crust and the mantle
Mohorovičić Discontinuity (Moho)
the ability of solid to flow
Plasticity
process by which new ocean floor is formed near the mid-ocean ridge and moves outward
Seafloor Spreading
the process in which the crust plunges back into the Earth
Subduction
branch of geology that deals with the movements that shape the Earth’s crust
Tectonics
Elements of Crust
Oxygen Silicon Aluminum Iron Calcium Sodium Potassium Magnesium Titanium Hydrogen
2 layers of crust
Upper layer: Granite
Lower layer: Basalt
An S-wave shadow zone is formed as seismic waves travel through the Earth’s body. Which of the following statements does this S-wave shadow zone indicate?
The outer core is liquid
