Chapter 12 - Earth's Interior & Geophysical Properties

Front 1

Gravitational force between two objects is determined by their _____ and the ____ between them.

Back 1

masses and distance

Front 2

Gravitational forces vary slightly at different locations on Earth's surface due to the shape of the Earth. Gravity is stronger at the ______ and weaker at the ______.

Back 2

Poles

Equator

Front 3

True or False. Differences in density of materials in Earth's interior produces small differences in local gravity field.

Back 3

True

Front 4

If mass above the compensation depth is uniform (isostatically balanced) with no excess or deficiency in mass, thus ____ gravity anomalies.

Back 4

no

Front 5

If mass above the compensation depth is not uniform and there is an excess mass of dense mantle below the mountain (no crustal root) then it will generate _______ gravity and thus, a _____ gravity anomaly.

Back 5

increased

positive

Front 6

If mass above the compensation depth is not uniform and there is a deficiency of mass below low area (too much crust) generates _____ gravity and a ______ gravity anomaly.

Back 6

decreased

negative

Front 7

Earth's magnetic field is generated in the Earth's _______ as it spins and convects and produces _______.

Back 7

liquid outer core

electrical currents

Front 8

Why does Earth's magnetic field change over time?

Back 8

The rotation of the outer core.

Front 9

The Earth's magnetic field inclination is _______ at the poles and ______ near the equator.

Back 9

Steeper

Horizonal

Front 10

What is "normal" polarity?

Back 10

North is north and South is South

Front 11

What is "reversed" polarity?

Back 11

South is North and North is South

Front 12

Rocks and minerals that cool through Curie temperature and stay below that temperature record magnetic field at ________.

Back 12

The time of their cooling

Front 13

the study of ancient magnetic fields in rocks and the reconstruction of past fields.

Back 13

paleomagnetism

Front 14

Magnetic alignment preserve din magnetite records ______ of Earth's magnetic field.

Back 14

orientation

Front 15

Are the lengths of magnetic periods uniform?

Back 15

No. This likely relates to turbulent flow of outer core.

Front 16

Magnetic material below the surface "add" magnetism and creates a _____ magnetic anomaly.

Back 16

positive

Front 17

What are some examples of magnetic rocks?

Back 17

iron ore, gabbro, and granite

Front 18

Removal of magnetic material from near the surface causes a _____ magnetic anomaly. (Ex. normal faulting)

Back 18

negative

Front 19

Earth's magnetic field is a self-generating and self-reversing dynamo in the _______.

Back 19

Outer Core

Front 20

What is the result of convection in the mantle?

Back 20

Warm rock rises as narrow pipe-like plumes.

Front 21

Which layer of Earth has the smallest volume?

Back 21

The Crust

Front 22

Who discovered the crust-mantle seismic discontinuity? In what year?

Back 22

Andrija Mohorovicic in 1909

Front 23

What is the best evidence of Earth having a solidified inner core?

Back 23

P waves travel faster in the inner core than in the outer core.

Front 24

Which layer of Earth does not transmit S waves?

Back 24

Outer core

Front 25

The boundary between the crust and the mantle was discovered in 1909 using ______ and now bears he name ______ after Mohorovicic.

Back 25

Seismic waves

Moho

Front 26

At the base of the crust, the velocity of P waves ________ abruptly, so Mohorovicic determined that the waves were traveling through two different layers composed of different materials.

Back 26

increases

Front 27

Who calculated the 2900 km to the core boundary depth? When? Is this value still accepted today?

Back 27

Beno Gutenberg

1914

Yes

Front 28

Who published the book "On the Origin of Continents and Oceans"? What year?

Back 28

Alfred Wegener, 1915

Front 29

Who developed the Richter magnitude scale? When?

Back 29

Charles F. Richter, 1935

Front 30

Which layer of the Earth includes the zone called the "asthenosphere" (the "weak sphere")?

Back 30

The Upper Mantle

Front 31

What does the upper mantle include? (Which "spheres")

Back 31

lower part of the rigid lithosphere and the weak asthenosphere.

Front 32

How much volume of the Earth is the mantle?

Back 32

82%

Front 33

How much volume of the Earth is the core? (outer + inner)

Back 33

16%

Front 34

Where does Earth's magnetic field originate?

Back 34

the outer core

Front 35

Which rock type is probably the closest in chemical composition to the upper mantle?

Back 35

Peridotite. It is an ultramafic rock composed mostly of the minerals olivine and pyroxene and is richer in iron and magnesium than rocks found in either the continental or oceanic crust.

Front 36

Which layer of Earth is very dense and solid and consists most likely of an iron-rich alloy?

Back 36

The inner core

Front 37

What structure in Earth is thought to be caused by a change in the mineral structure of olivine?

Back 37

The 660-km-depth discontinuity or transition zone

Front 38

At high latitudes, the force lines intersect Earth's surface at _____ angles.

Back 38

steep

Front 39

How was the diameter of Earth's core and the nature of the outer core discovered?

Back 39

Through analysis of he P-wave and S-wave shadow zones.

Front 40

What causes the P-wave shadow zone?

Back 40

Refraction of P waves crossing the mantle-outer core boundary.

Front 41

What causes Earth's magnetic field?

Back 41

Weak electrical currents associated with fluid motions of molten iron in the outer core.

Front 42

Which of Earth's layers is marked at its top by the Mohorovicic discontinuity?

Back 42

the Mantle

Front 43

Which sphere would be characterized as a zone of softened peridotite in the upper mantle.

Back 43

the asthenosphere

Front 44

What is the upper layer of the lithosphere called?

Back 44

Crust

Front 45

Which rocks are the closest to the average chemical composition of the oceanic crust?

Back 45

Basalt and gabbro

Front 46

______ are probably major components of Earth's inner core.

Back 46

Crystalline iron and nickel

Front 47

Which materials will transmit seismic waves most rapidly? (more or less rigid materials?)

Back 47

More rigid

Front 48

A seismic wave may change direction, without bouncing back, when crossing the boundary between two rock types. This phenomenon is called ________.

Back 48

Refraction

Front 49

Which is Earth's weakest layer?

Back 49

Asthenosphere

Front 50

Where do the rocks of the ocean crust form?

Back 50

At mid-oceanic ridges

Front 51

The seismic boundary between the crust and the mantle is referred to as the __________.

Back 51

Mohorovicic discontinuity

Front 52

The greatest change in the velocity of P waves occurs at the __________ boundary.

Back 52

mantle–outer core

Front 53

The source of heat that produces deep mantle plumes is believed to be located at the __________.

Back 53

outer core–mantle boundary or the "D" layer.

Front 54

Approximately how deep is Earth's core–mantle boundary?

Back 54

2900 kilometers

Front 55

How does the rotational speed of the inner core compare with the rest of the planet?

Back 55

Perhaps a century or more faster

Front 56

__________ is the transfer of heat by the mass movement or circulation in a substance.

Back 56

Convection

Front 57

It is thought that convection within the __________ of the rotating planet generates Earth's magnetic field.

Back 57

Outercore

Front 58

What are the physical properties of each layer?

Back 58

A. Solid iron and nickel composition

B. Liquid iron and nickel composition

C. Rich in the mineral perovskite

D. Composed of the ultramafic rock peridotite

E. Composition comparable to granodiorite

F. Predominantly basalt

Front 59

What did Andrija Mohorovicic do?

Back 59

He discovered the discontinuity between the crust and the mantle in 1909.

Front 60

What did Inge Lehman do?

Back 60

Discovered the boundary between solid inner core and liquid outer core in 1936.

Front 61

What did Richard Dixon Oldham do?

Back 61

Discovered the central core of the earth in 1906 using the shadow effect of P and S waves.

Front 62

What did Beno Gutenberg do?

Back 62

Calculated the depth to core boundary at 2900 km.

Front 63

Continents lose heat faster than old oceanic seafloor because they contain higher amounts of heat-producing ___________.

Back 63

Radioactive isotopes