Structure and Composition of the Earth and Plate Tectonic Theory

Question 1

What is the layer between the crust and the mantle?

Answer 1

The Moho

Question 2

What is the density of oceanic crust?

Answer 2

2.9 g/cm3

Question 3

How thick is oceanic crust?

Answer 3

5-10km

Question 4

What is the composition of oceanic crust?

Answer 4

Basalt

Question 5

What is oceanic crust rich in?

Answer 5

Fe and Mg

Question 6

What is the density of continental crust?

Answer 6

2.7 g/cm3

Question 7

How thick is continental crust?

Answer 7

90km

Question 8

What is the composition of continental crust?

Answer 8

Granite

Question 9

What is continental crust rich in?

Answer 9

Al and Si

Question 10

What is the density of the mantle?

Answer 10

3.3 g/cm3

Question 11

What is the composition of the mantle?

Answer 11

Peridotite

Question 12

What is the density of the core?

Answer 12

12 g/cm3

Question 13

What is the composition of the core?

Answer 13

Iron and nickel

Question 14

Where is the 1,300 degree isotherm?

Answer 14

Between the lithosphere and asthenosphere

Question 15

What state is the lithosphere?

Answer 15

Rigid

Question 16

What state is the asthenosphere?

Answer 16

Rheid

Question 17

Where is the Gutenberg Discontinuity?

Answer 17

Between the mantle and the outer core

Question 18

Where is the Lehmann Discontinuity?

Answer 18

Between the outer and inner core

Question 19

What state is the outer core?

Answer 19

Liquid

Question 20

What state is the inner core?

Answer 20

Solid

Question 21

Define Lithospheric Plates

Answer 21

Regions of the Earth’s crust and upper mantle that are fractured into plates that move across a deeper plasticine mantle

Question 22

What are the seven major tectonic plates?

Answer 22

African, Antarctic, Eurasian, Indo-Australian, North American, Pacific, South American

Question 23

What are the four classifications of rock by Victor Goldschmidt?

Answer 23

Lithophile (rock loving), Siderophile (iron loving), Chalcophile (ore loving), Atmophile (gas loving)

Question 24

What is a limitation of Goldschmidt’s Classification?

Answer 24

It can depend on temperature, pressure and the chemical environment e.g. pH

Question 25

Define Minerals

Answer 25

Naturally occurring inorganic chemical compounds or elements with compositions that can be expressed as chemical formulae

Question 26

What can minerals be identified through?

Answer 26

Compositions, Atomic structures, Physical properties

Question 27

Define Silicates

Answer 27

Minerals that contain a fundamental building block called a silica tetrahedron

Question 28

What is a silica tetrahedron made from?

Answer 28

Four oxygen bounding a single silicon

Question 29

What are the five types of silica tetrahedron?

Answer 29

Single (e.g. olivine), Single chain (e.g. augite), Double chain (e.g. hornblende), Sheet (e.g. mica), Framework (e.g. quartz)

Question 30

What eight diagnostic properties of minerals?

Answer 30

Colour, Crystal shape, Lustre, Hardness, Cleavage, Relative density, Streak, Reaction with acid

Question 31

What are the four types of lustre?

Answer 31

Metallic, Vitreous, Greasy, Pearly

Question 32

What is the hardness of a fingernail on Mohs Hardness Scale?

Answer 32

2.5

Question 33

What is the hardness of a copper coin on Mohs Hardness Scale?

Answer 33

3.5

Question 34

What is the hardness of a steel pin on Mohs Hardness Scale?

Answer 34

5.5

Question 35

What are four pieces of direct evidence for the structure and composition of the earth?

Answer 35

Rocks at the surface, Boreholes and mines, Ophiolites, Volcanic rocks with xenoliths

Question 36

What is P wave velocity affected by?

Answer 36

Rigidity and incompressibility

Question 37

What is S wave velocity affected by?

Answer 37

Density and rigidity

Question 38

Define Shadow Zone

Answer 38

Region of the earth that receives no or just some of the different seismic waves

Question 39

What causes P wave shadow zones?

Answer 39

Due to the change from solid mantle to liquid outer core causing the P waves to slow down and refract from this surface

Question 40

What causes S wave shadow zones?

Answer 40

Due to the change from solid to liquid outer core, the liquid doesn't allow the S waves to propagate through it

Question 41

What is the average density of the earth?

Answer 41

5.5 g/cm3

Question 42

What are the two main types of meteorite found on earth?

Answer 42

Iron meteorites and Stony meteorites

Question 43

What do iron meteorites represent?

Answer 43

The core

Question 44

What do stony meteorites represent?

Answer 44

The crust and the mantle

Question 45

What three things does the earth's magnetic field change in?

Answer 45

Strength, Position of the poles relative to the axis, N and S poles intermittently switch positions

Question 46

Define Geotherm

Answer 46

A line that shows temperature variation of rock with depth

Question 47

Define Geothermal Gradient

Answer 47

Change in temperature over a given depth

Question 48

When the geotherm is higher than the solidus...

Answer 48

The rock partially melts

Question 49

What are four pieces of evidence which confirms the earth is hotter inside than at the surface?

Answer 49

Temperature in mines, Hot springs, Volcanic activity, Surface heat flow

Question 50

What are two sources of internal energy/heat?

Answer 50

Initial heat from the Big Bang, Break down of radiogenic elements

Question 51

What are six pieces of evidence to define plate boundaries?

Answer 51

Earthquake zones, Volcanoes, Trenches and rifts, Mountain belts, Heat flow, Variation in gravity readings and anomalies

Question 52

What are three mechanisms for plate movement?

Answer 52

Convection currents, Ridge push, Slab pull

Question 53

When are negative magnetic anomalies induced?

Answer 53

When the rock cools and solidifies with the Earth's north magnetic pole in the southern geographic hemisphere

Question 54

What are four factors affecting gravity?

Answer 54

Radius of the earth, Latitude, Altitude, Density of the rocks