ISS Chapter 2

Question 1

What are the three main compositional layers of the Earth?

Answer 1

Core, mantle, and crust.

Question 2

What is the composition of the Earth’s solid inner core?

Answer 2

Iron with around 4% nickel.

Question 3

What is the composition of the Earth’s liquid outer core?

Answer 3

Iron, nickel, and a lighter element (which is most likely oxygen or sulphur).

Question 4

How deep can the deepest mines go into the crust of the Earth?

Answer 4

About 15 km.

Question 5

What is plate tectonics?

Answer 5

The study of the movement of the Earth’s plates.

Question 6

What are plutonic rocks?

Answer 6

Rocks formed at great depths within the Earth.

Question 7

How are deeply formed rocks brought to the surface of Earth?

Answer 7

They are carried to the surface by molten lava and preserved when the lava hardens.

Question 8

What are xenoliths?

Answer 8

Rocks unusual to the Earth’s surface and usually brought in from deeper underground by lava flows.

Question 9

What is self-compression?

Answer 9

The compacting of rock or another material due to the weight or pressure from an overburden.

Question 10

What is the SI unit of pressure?

Answer 10

The pascal or Pa.

Question 11

What is the pascal converted to other SI units?

Answer 11

1 Pa = 1 N m^-2 = 1kg m^-1 s^-2

Question 12

The kbar is often used to describe pressure on other planets. How many times Earth’s atmospheric pressure at sea level is 1 kbar?

Answer 12

The pressure af sea-level is 1 bar and 1kbar is 1000 times the sea-level pressure.

Question 13

How do crystal structures change under the influence of pressure?
Hint: there are two ways in which they change.

Answer 13

1. The atoms are rearranged to form a more dense crystalline structure
2. Chemical reactions change the material to produce a denser material.

Question 14

What is peridotite?

Answer 14

A mineral from deep within the Earth brought to the surface by lava flows.

Question 15

What is the difference between a meteor, a meteoroid, and a meteorite.

Answer 15

A meteor is a fiery object travelling through the atmosphere.
A meteoroid is a small object travelling through space.
A meteorite is a meteor that has survived to strike the surface.

Question 16

What is a chondrule?

Answer 16

Mineral droplets within a rock that are around 0.1 to 2mm in diameter.

Question 17

What are CI carbonaceous chondrites?

Answer 17

A class of meteorites that contain chondrules and are believed to be the most primitive of meteorites.

Question 18

What are primitive meteorites?

Answer 18

Primitive means their composition resembles that of material that condensed from the Solar Nebula.

Question 19

What is chondritic composition?

Answer 19

A material has a chondritic composition if it has the same elements as chondritic meteorites.

Question 20

What is used to detect the layers of the Earth?

Answer 20

Seismic waves.

Question 21

What are p-waves?

Answer 21

Pressure/compression waves.

Question 22

What are s-waves?

Answer 22

Shearing waves.

Question 23

What materials can p-waves and s-waves travel through?

Answer 23

P-waves: solids and liquids.
S-waves: only solids.

Question 24

What is the Mohorovicic discontinuity (Moho)?

Answer 24

The compositional boundary between the Earth’s mantle and crust.

Question 25

S-waves cannot propogate through the outer core, why?

Answer 25

Because it is a liquid.

Question 26

What is a magnetic dipole?

Answer 26

An object with similar properties to a bar magnet.

Question 27

Which of the terrestrial planets has the strongest magnetic field?

Answer 27

Earth.

Question 28

What is the most important consequence of Earth's magnetic field?

Answer 28

High energy ionized particles from the Sun's solar wind are deflected.

Question 29

What is the space around a planet which affects ionized particles called?

Answer 29

The magnetosphere.

Question 30

What is the composition of the Earth's core?

Answer 30

Nickel and iron.

Question 31

What is the composition of the Earth's mantle?

Answer 31

Peridotite which is dominated by olivine and pyroxene minerals.

Question 32

What is the composition of the Earth's crust?

Answer 32

Ocean crust: mostly basalt Continental crust: broadly speaking granite-like in composition.

Question 33

What are refractory substances?

Answer 33

Those with the highest tolerance for heat, or the highest condensation/vaporisation point.

Question 34

What are volatile substances?

Answer 34

Substances with the lowest condensation/vaporisation point.

Question 35

What is a condensation sequence?

Answer 35

A progression from the most refractory substances to the most volatile.

Question 36

What is differentiation in the context of a planet/body?

Answer 36

The seperating out of elements or substances dependent on their chemical properties.

Question 37

What is partial melting?

Answer 37

When a rock melts different materials within will melt at different temperatures.

Question 38

What is element partitioning?

Answer 38

The exchange of elements between solid and liquid states.

Question 39

What model currently best describes the formation of the Moon?

Answer 39

It is believed to be the leftover material from impacts between the early Earth and another planetary embryo.

Question 40

What are tektites?

Answer 40

Droplets of glass formed from instantaneous melting of target rock and an impactor.

Question 41

What is accretional heating?

Answer 41

Heat generated from impacts and the resultant melting.

Question 42

What is tidal heating?

Answer 42

Heating created by shape distortions resulting from mutual gravitational attraction.

Question 43

What is radiogenic heating?

Answer 43

Heating resulting from radioactive decay.

Question 44

What is radiometric dating?

Answer 44

A method of using radioactive decay to age an object.

Question 45

What is the half-life of a radioactive element?

Answer 45

The time taken for half of the atoms in a sample of the material to decay into another element.

Question 46

What is the surface area to volume ratio?

Answer 46

Surface area/volume.

Question 47

What is conduction?

Answer 47

Heat moves through one material and into another.

Question 48

What is convection?

Answer 48

Heating a material makes it less dense and it rises through the surrounding material taking heat with it.

Question 49

What is solid-state convection?

Answer 49

Convective flow in an otherwise solid appearing material, such as within mineral crystals.

Question 50

What is the asthenosphere?

Answer 50

The protion of the mantle where heat and pressure allow convective flow and heat transfer to exist.

Question 51

What is the lithosphere?

Answer 51

Solid crust which cannot permit flow.

Question 52

What seperates the asthenosphere and lithosphere?

Answer 52

A difference in mechanical properties, ie flow.

Question 53

What is the low velocity zone?

Answer 53

A partially liquid area of the Earth's mantle where the velocity of both p-waves and s-waves decrease.

Question 54

What is advection?

Answer 54

A physical transer of heat by magma moving from a deeper area upwards through fractures and transfering heat as it cools.

Question 55

What is a mid-ocean ridge system?

Answer 55

Areas where new crustal material is added from below.

Question 56

What is a subduction zone?

Answer 56

An area where one tectonic plate is drawn underneath another and recycled into the mantle.

Question 57

What is plate recycling?

Answer 57

Where crust is subducted into the mantle and remelted.

Question 58

What is a mantle plume?

Answer 58

An area of upwelling of hot material from deep within the mantle that causes bulges in the overlying lithosphere.

Question 59

What are hot spots?

Answer 59

Areas of increased volcanic activity.

Question 60

What are the Moon's maria?

Answer 60

The darker 'lunar sea' areas of the moon.

Question 61

What are the highland regions of the Moon?

Answer 61

Thet are the brighter heavily cratered areas.