Phys 1415 Chapter 21

Tensional forces cause the crust to

Break and fracture thereby lengthening the crustal surface

In comparison to P-waves, S-waves

Can travel only through solids- not in fluids

The lithosphere includes

Continental and oceanic crust and the upper part of the mantle

The theory of seafloor spreading is attributed to

Harry Hess

The Mercalli scale measures an earthquake's

Intensity damage and overall effect

Which seismic waves produce a wave shadow?

P and S waves

The theory of seafloor spreading is supported by

Paleomagnetic analysis of the ocean's floor

Granite does not readily form near oceanic-oceanic convergent boundaries because

all of the above

Evidence to support the fact that Earth's central core is solid can be attributed to

an increase in P- wave velocity as they encounter and move through the inner core.

The theory of continental drift is supported by paleoclimatic data, the jig-saw fit of the continents

at their continental margins, and paleontology

The top of the mantle is the same as the

base of crust

The energy in an earthquake is released

before the quake, after the quake, and during the quake.

In a folded sequence of rocks we find younger rocks at the axis of the fold and older rocks away from the fold axis. The fold is

called a syncline.

The Mohorovicic discontinuity occurs because of a

change in the composition of rocks on both sides of the boundary

Earth's magnetic field is not stable; throughout geologic time it has changed direction. This change is attributed to

changes in the direction of fluid flow in the molten outer core

Reverse faults are the result of

compression

Volcanoes do not form at which type of convergent plate boundary?

continental-continental convergent boundaries

Water causes partial melting of the mantle at which type of plate boundary

convergent boundaries

Isostasy is

crustal equilibrium relative to the mantle

Volcanic activity is associated with

divergent and convergent boundaries

An anticline is a fold in which the limbs bend

downward

An Earthquake occurs as

energy released from Earth's interior travels in the form of seismic waves to Earth's surface

Earth's internal layers were discovered by studying the movement of P- and S- waves through Earth's interior. In comparison to S-waves, the movement of P- waves is

fast, compressing and expanding the rock as they move through it

A tsunami is unlike most other water waves mainly because it

has a very long wavelength

Detailed mapping of the ocean floors revealed

huge mountain ranges on the ocean floor, and deep trenches near some of the continents

The mantle is composed of

iron-rich silicate rocks

Motion in a P-wave is

longitudinal

The asthenosphere is part of the

mantle

The Mohorovicic discontinuity marks the change in rock density elasticity between the

mantle and crustal surface

Spreading centers occur along

mid-ocean ridges

As hot mantle rock rises, it expands. As it expands it cools. This cooler rock is

more dense so it sinks. This contributes to the heat flow convection process.

Mountains tend to form in long narrow ranges because

of plate convergence- plates coming together.

Secondary waves can travel through all areas of Earth except the

outer core

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

Plate tectonics differs from continental drift because it

provides a credible driving force

When rock is subjected to compressive force, it may fault. If rocks in the hanging wall are pushed up over rocks in the footwall, it is called a

reverse fault

The concept of seafloor spreading states that

seafloor is created at mid-ocean ridges and destroyed at deep ocean trenches.

The primary evidence that the outer core is molten is an abrupt

stop of S-wave propagation, and a decrease in P-wave velocity.

The San Andreas fault in California is a

strike-slip fault

The process in which one plate bends and descends beneath another plate is called

subduction

The dominant force at divergent boundaries is

tension

Divergent boundaries are areas of

tensional forces that stretch the crust and generate a spreading center

The stress that occurs when material is pulled apart is called

tensional stress

The speed of a seismic wave depends on

the type of material it travels through

Evidence to support that the inner core is solid and the outer core is liquid comes from

the wave shadow effect of P and S waves, and the increase in velocity of P-waves as they encounter the solid inner core.

The outer core is liquid because

there is less weight, and thus less pressure on it

According to plate tectonic theory, the San Andreas fault is a

transform fault

The thickness of Earth's crust

varies from 10 km under the oceans to 60 km under the continents

Regions in which earthquakes are common are also regions in which

volcanoes are common

Wegener's theory of continental drift

was not accepted by the scientific community of the early 1900s