Exam 2 Earth and space

Name two types of body waves.

P waves and S waves

How does plate tectonics differ from continental drift?

Plate tectonics not only states that Earth's plates move, it explains why they must move in terms of fundamental laws of physics.

Why are plate boundaries the sites of most geologic activity?

Plates interact with one another at their boundaries.

How do plates move at divergent plate boundaries?

Plates move apart.

What is the relationship between the crust and lithosphere?

The crust is part of the lithosphere.

How often does the Earth's magnetic field switch polarity?

every 100,000 to several million years

Which of the following is not a type of tectonic plate boundary?

fault plate boundary

Seafloor spreading provides the mechanism for continental drift, because at the spreading center

formation of new lithosphere pushes the continents

The hypothesis of continental drift was supported by the jigsaw fit of the continents, similar

fossils, matching rock types, and ancient ice sheets

Describe how tectonic plates move in terms of speed.

from 2 cm per year to about 15 cm per year

Earth Sciences 10 Describe how tectonic plates move in terms of speed

from 2 cm per year to about 15 cm per year

In the continental crust?

granitic

The ultimate cause for tectonic plate movement is

heat transfer away from Earth's interior, and gravity

What features at the surface provide evidence of plumes?

hot spots

The core of Earth is probably composed of

iron and nickel

Alfred Wegener supported his theory of continental drift by

making a connection between the rocks, rock structures, and plant and animal fossils found in both Africa and South America.

Which geologic features are associated with divergent boundaries?

mid-ocean ridges and continental rift valleys

Spreading centers occur along

mid-ocean ridges.

Convection is a

mode of heat transfer that carries heat from Earth's core toward its surface.

Describe how tectonic plates move in terms of direction.

move in different directions

Complete this statement: Divergence is to moving away as convergence is to

moving toward

Earth Sciences 8 Complete this statement: Divergence is to moving away as convergence is to

moving toward

What forms at divergent plate boundaries?

new oceanic lithosphere

When the magnetic field of Earth is reversed,

newly formed mineral grains on the ocean floor are magnetized according to the new orientation of the magnetic field.

Which geologic features are associated with convergent boundaries?

ocean trenches and volcanoes

New lithosphere is formed at

ocean trenches.

Where would you expect to see alternating bands of rock with different magnetic polarities?

on both sides of the mid-ocean ridge

In general, where do volcanoes form in subduction zones?

on the overriding plate, away form the convergent boundary

The theory of seafloor spreading is supported by

paleomagnetic analysis of the ocean's floor.

We can say that Earth's crust floats on the mantle because

part of the mantle is hot enough to flow as a plastic solid.

Convergent boundaries are areas of

plate collision.

How do plates move at transform plate boundaries?

plates move side by side

How do plates move at convergent plate boundaries?

plates move together

Continental crust is very buoyant compared with oceanic crust because continental crust is

predominantly composed of granitic rocks, whereas oceanic crust is composed of basaltic rocks.

The inner core is solid because

pressure from the weight of the surrounding layers prevents the inner core from melting.

The fastest seismic wave is a

primary wave

Seismic waves are classified as body waves and surface waves. An example of a body wave is a

primary wave (P-wave).

Earth's internal layers were discovered by studying

seismic waves.

How long does it typically take for the first earthquake waves to arrive at a seismograph after the earthquake occurs?

several minutes

The two elements that make up about 75% of Earth's crust are__________ and________

silicon and oxygen

What are the two primary types of waves generated by earthquakes?

surface waves and body waves

Earth Sciences11 What are the large, interlocking pieces of lithosphere called?

tectonic plates

What are the large, interlocking pieces of lithosphere called?

tectonic plates

The ultimate cause of tectonic plate motion is the

tendency for heat to spread out. second law of thermodynamics. escape of heat from Earth's interior.

Earth Sciences 14 Continental plates tend to move slower than oceanic plates because

their roots extend deep into the mantle

Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates closely with plate boundaries.

transform

Tectonic plates move beside one another at

transform plate boundaries.

Regions in which earthquakes are common are also regions in which

volcanoes are common.

The earthquakes that occur in Southern California generally occur above a

Fault

What accounts for most tectonic plate motion?

Forces at subduction zones

The lithosphere floats atop the

asthenosphere.

Earth Sciences 9 Where are tectonic plates located?

at Earth`s surface

What kind of rock is most common in the oceanic crust?

basalt

How are normal polarity and reverse polarity of Earth's magnetic field different?

A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity.

What is the underlying principle of seismograph construction?

A heavy weight suspended within a moving box needs to overcome inertia, resulting in a slight delay in the motion of the weight after the box moves.

In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?

A record of Earth's magnetic field is recorded in oceanic rocks, which show a clear pattern of changes in Earth's magnetic polarity.

When will reflection and refraction occur simultaneously?

A wave will reflect and refract when it encounters a boundary between two layers of different velocity.

The theory of continental drift is credited to

Alfred Wegener.

Which of the following mountain ranges are examples of continental arcs?

Andes and Cascades

Where do body waves and surface waves travel?

Body waves travel within Earth, and surface waves travel along Earth's surface.

What do vertical and horizontal surface waves have in common?

Both waves travel along Earth's surface and decrease in amplitude with depth below the surface.

The density of Earth's crust, mantle, and core increases moving toward Earth's center because

Early in Earths history, it separated into layers according to density.

Why do we say that Earth science is an integrated science?

Earth science encompasses a broad spectrum of natural science disciplines, including physics, chemistry, biology, and astronomy.

Which of the following statements about Earth's magnetic field is most accurate?

Earth's magnetic field switches polarity at irregular time intervals.

What is the relationship between temperature and density?

In general, warmer materials are less dense, and colder materials are denser.

Which of the following statements about reflection and refraction is most accurate?

Reflection is the bouncing of waves, whereas refraction is the bending of waves.

How does rock within Earth change as S waves pass?

Rocks within Earth are displaced up and down as S waves pass.

How do rocks within Earth change as P waves pass?

Rocks within Earth both expand and contract as P waves pass.

How are S waves and vertical surface waves different?

S waves are body waves, whereas vertical surface waves are surface waves. The amplitude of S waves does not decrease with depth, but the amplitude of vertical surface waves does decrease with depth.

found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.

Seafloor crust

The slowly increasing distance between South America and Africa is due to

Seafloor spreading

Layered____exposed by erosion can be seen when looking at the Grand Canyon in the United States.

Sedimentary Rock

The extremely deep ocean Marianas Trench is a result of

Subduction

What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?

The Earth would increase in volume.

What does this suggest about the rate of seafloor spreading compared to the rate of subduction?

The rate of subduction is about equal to the rate of seafloor spreading.

How will a wave change as it moves from a layer of higher velocity into a lower layer of lower velocity?

The wave will bend toward the left.

How will a wave change as it moves from a layer of lower velocity into a lower layer of higher velocity?

The wave will bend toward the right.

Why are volcanoes NOT found at transform boundaries?

Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.

What type of plate boundary is the San Andreas Fault?

Transform fault

Where are tectonic plates located?

Where are tectonic plates located?

What is convection?

a cycle of moving material formed by the rise of less-dense material and the sinking of denser material

Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a

a hot spot

What is a volcanic arc?

a row of volcanoes that forms on the overriding plate near a subduction zone

When will the first earthquake waves arrive at a seismograph station?

a short time after the earthquake occurs

What is a plume?

a zone of upwelling material originating at the outer core-mantle boundary

Where is the youngest ocean floor found?

along the crest of mid-ocean ridges

What is a seismograph?

an instrument used to record earthquake waves

The East African rift is a divergent plate boundary that is splitting the continent of Africa into two pieces. What will eventually form around this divergent boundary?

an ocean

The upper mantle can be divided into two zones, the

asthenosphere in the lower upper mantle and part of the lithosphere in the upper part of the upper mantle.

The classes of seismic waves based upon the part of Earth they travel through are

body waves (P- and S-waves) and surface waves (Love and Rayleigh waves).

Australia is composed of relatively old and thick

continental crust

In general, where do earthquakes AND volcanic eruptions occur?

convergent plate boundaries and divergent plate boundaries

Earth's layer with the most brittle behavior is the

crust.

Which of the following terms best characterizes upwelling in the asthenosphere?

diffuse

Which type of plate boundary is most closely associated with the formation of new ocean floor?

divergent

What are the three types of plate boundaries?

divergent, convergent, and transform

Plates move apart at __________ boundaries, move together at __________ boundaries, and move side-by-side at __________ boundaries.

divergent/convergent/transform

The lithosphere rides on top of the asthenosphere. Lithospheric movement causes

earthquakes, volcanic activity, and mountain building activity.

The theory of plate tectonics states that

the lithosphere is broken up into several plates that move about as a result of convective motion in the asthenosphere.

Oceanic and continental crust differ in that

the oceanic crust is mainly composed of dark basaltic rock while the continental crust is mainly composed of lighter-colored continental rock. the continental crust is thicker on average than the oceanic crust. the continental crust is less dense than the oceanic crust.