Geology Test 1 Structure of Earth and Continental Drift and Plate Tectonics
Earth's core
generates Earth's magnetic field
The rate at which temperature increases as depth increases is the
geothermal gradient
Which of the following groups of elements make up most of the mass of the Earth?
iron, oxygen, silicon, and magnesium
Asthenosphere
is warm enough to flow slowly
The geothermal gradient
refers to the rate of increase in temperature with increasing depth in the Earth
Which of the following was used as evidence by Wegener to develop the theory of continental drift?
the presence of matching mountain chains on continents currently separated by oceans
Order the steps of continental volcanic arc formation
1. A subduction trench forms where the subducting plate bends downward into the mantle 2. An accretionary prism begins to form 3. Magma, created by flux melting of the mantle, rises through the overriding plate 4. Lava erupts onto the surface, forming volcanoes
Order the steps of volcanic island arc formation
1. A subduction trench forms where the subducting plate bends downward into the mantle 2. An accretionary prism begins to form 3. Magma, created by flux melting of the mantle, rises through the overriding plate 4. Lava erupts onto the surface, forming volcanoes
Place Earth's layers in order from highest to lowest density
1. Inner core 2. Outer core 3. Mantle 4. Crust
Identify statements true of Pangaea
1. Rates of seafloor spreading in the Atlantic Ocean are compatible with what is known about the breakup of Pangaea 2. Pangaea was one of several supercontinents that have formed and broken up during Earth's history 3. The regional-scale folds visible in the Appalachian Mountains are remnants of Pangaea's formation
Order the steps in supercontinent formation and breakup
1. Subduction consumes an ocean basin 2. Continents collide and form a supercontinent 3. Rifting takes place 4. Seafloor spreading produces new litosphere, and continents move apart
Order the steps that lead to seafloor spreading
1. The asthenosphere beneath diverging plates rises and melts 2. A mag,a chamber forms beneath the ridge axis 3. Magma rises to the surface and erupts via submarine volcanoes 4. Newly formed crust is moved laterally away from the ridge
Order the steps in continental rift formation
1. The litospheric mantle begins to stretch horizontally and thin vertically 2. The crust fractures, and faults develops 3. Large fault blocks of crust slide down into widening rift 4. Magma erupts as lava, creating volcanoes along and near the center of the rift
As the map below shows, the oldest seafloor is generally less than 200 million years old. Why?
All oceanic lithosphere eventually gets subducted beneath the continents by the time it is 200 million years old
Sort outcomes of continental collision versus those related to ocean-ocean (oceanic) convergence
Continental Collision crustal thickening mountain building Oceanic Convergence subduction volcanism
Match the geologic activity to the plate boundary where it occurs
Convergent deep and shallow earthquakes recycling of old oceanic crust volcanic arcs Divergent new oceanic crust shallow earthquakes and volcanic activity Transform earthquakes but no volcanic activity
Decide which type of plate boundary the following items would most likely be associated with
Divergent Boundary crustal thinning Convergent Boundary andesitic volcanism crustal thickening Transform Boundary shear stress
The lithosphere and asthenosphere are known as physically different layers of the Earth because they behave very differently when deformed.Sort the items below into the correct boxes based on characteristics of the lithosphere and asthenosphere
Lithosphere mantle and crust brittle colder Asthenosphere mantle only ductile warmer
Sort statements as being true of the lithosphere or asthenosphere
Lithosphere outermost layer relatively rigid Asthenosphere higher density relatively soft (plastic)
Which of the following statements about lithosphere and asthenosphere is TRUE?
Lithosphere consists of the crust and the upper mantle, and behaves like a hard layer that breaks and bends
The boundary separating the crust from the mantle is called the
Moho
Why is the lithosphere rigid while the asthenosphere is not?
The temperature in the asthenosphere is higher than the lithosphere so the rock is softer
describe where Earth's three most abundant elements (iron, oxygen, and silica) are located
The majority of oxygen is located in the crust and mantle The majority of iron is located in the core Silica is abundant in the mantle and crust
Why is Earth's mantle solid?
The pressure is so high that molecules cannot vibrate enough to form freely moving liquid
Plate tectonics theory took decades to be accepted because
Wegener couldn't explain how continents moved
The Himalayas are currently growing because at their location
a continental plate is colliding with another continental plate
Seafloor spreading is driven by volcanic activity that occurs
along mid-ocean ridges
Alfred Wegener proposed the idea of continental drift after he observed evidence from fossils, glacial deposits, and the fit of the continents that suggested all of the continents were once
combined to form a supercontinent (which he termed Pangaea) in the late Paleozoic through the Mesozoic
Which of Earth's layers is the thinnest?
crust
The Moho is the boundary between Earth's
crust and mantle
Which of Earth's layers accounts for most of the volume of Earth?
mantle
The center of a mid-ocean ridge is where
new oceanic lithosphere is being created
During the process of seafloor spreading
new seafloor is formed at ridges and destroyed at trenches
The two most common gases of Earth's atmosphere are
nitrogen (N2) and oxygen (O2)
The Earth's magnetic field is generated by which of the following layers?
outer core
Which layer of the Earth's interior is completely molten?
outer core
Which layer or sublayer of the Earth would you find at 4700 km below the surface?
outer core
Which of the following has faulting but no volcanic activity?
transform plate boundary
A subducting (or downgoing) plate
will have a trench associated with it