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