Unit 1 - Plate Tectonics

Question 1

crust

Answer 1

solid, thin outermost layer

Question 2

mantle

Answer 2

• two parts (upper and lower)
• solid that behaves like a liquid (it flows)
• thickest layer of the Earth

Question 3

outer core

Answer 3

• liquid layer of iron and nickel

Question 4

inner core

Answer 4

• solid dense ball of mostly iron
• innermost layer of earth

Question 5

solar nebula

Answer 5

• a disc of gas and dust that surround all new stars
• Earth formed from the accretion of metal from a solar nebula

Question 6

why inner core is solid and outer core is liquid

Answer 6

• denser elements (like iron) sink to the center
• formed inner core, intense pressure from the rest of the Earth keeps inner core from melting

Question 7

differentiation

Answer 7

• the sinking of metals to form the core and the rising of materials to form the crust/mantle comes from different densities of liquid
• also happens because of the force of gravity

Question 8

plate tectonics

Answer 8

the process by which pieces of of a strong lithosphere (rigid plates) move around over a weak asthenosphere (weaker substrate)

Question 9

lithosphere

Answer 9

• Aka rigid plate, made up of crust/upper mantle
• Earth’s surface is a mosaic of 18 plates
• Very rigid/strong

Question 10

asthenosphere

Answer 10

• weak substrate, allows plates/lithosphere to move
• crust is solid, but asthenosphere acts like a liquid to allow them to move (like silly putty)

Question 11

why hotter mantle below asthenosphere doesn’t flow as easily

Answer 11

The hotter mantle beneath the asthenosphere does not flow as easily because of the significantly higher pressure at that depth

Question 12

evidence of continental drift by Alfred Wegener

Answer 12

• North and South America coastlines fit with Europe and Africa
• identical volcanic rocks appear on both sides of the Atlantic
• Fossils of non-swimming animals found on both sides of the modern oceans

Question 13

why few scientists accepted Wegener’s theory of continental drift

Answer 13

• it requires strong oceanic crust to get out of the way of the moving continents
• was not clear what force would cause continents to move

Question 14

magnetic reversal

Answer 14

• crystals in lava flows act like tiny compasses and show that the north and south magnetic poles often switched places
• volcanic rocks have allowed us to track magnetic reversals back hundreds of millions of years

Question 15

observation that led to theory of plate tectonics

Answer 15

• magnetic reversals in volcanic oceanic crustal rocks on the seafloor were found
• allowed us to use the volcanic rock on land to determine their age
• revealed spreading centers on seafloor where new ocean crust forms and moves
• mobility of ocean crust meant that continents could move around without plowing into oceans

Question 16

mid-ocean ridge

Answer 16

magma from below reaches the surface, cools to form new ocean lithosphere, then moves outwards from the ridge

Question 17

subduction zone

Answer 17

-Earth isn’t growing, so ocean crust must also be destroyed
- happens at subduction zones where ocean plates dive (subduct) back into the Earth’s interior
- give rise to the highest mountains, deepest trenches, largest earthquakes, and most of earth’s volcanoes

Question 18

kind of plate boundary San Andreas is

Answer 18

• San Andreas fault is a transform plate boundary between the Pacific and North American plates
• not all boundaries between continental and oceanic crust are plate boundaries (called passive margins)

Question 19

transform plate boundary

Answer 19

tectonic plates that slide past each other on the surface of the Earth horizontally

Question 20

conduction

Answer 20

heat transfer through a solid through the spread of vibrations on the atomic scale

Question 21

convection

Answer 21

• heat transfer through fluid motions of liquids and gasses & solids that flow like a liquid
• leads to fluid circulation as hot volumes rise and cool volumes sink

Question 22

radioactive heat

Answer 22

heat transfer through electromagnetic waves (light) through a transparent (clear) medium

Question 23

when a solid can convect

Answer 23

• Earth’s mantle is a solid (crystalline structure) but flows like a fluid and thus transfer heat through convection
• called solid state convection

Question 24

what drives plate tectonics

Answer 24

• plate tectonics is the surface expression of mantle convection (circulation of hot/cold fluid)

Question 25

what caused a magnetic field to be produced

Answer 25

- the motion of electrons in all atoms gives rise to small magnetic fields - if fields are randomly oriented, no net magnetic no net magnetic field will form - if fields are aligned a net magnetic field will form

Question 26

how a permanent magnet is created

Answer 26

A "permanent" magnet can be created by temporarily placing a metal (ferromagnetic material) inside a strong magnetic field, like the iron nail in this setup.

Question 27

true magnetic poles vs. geographic

Answer 27

true magnetic poles are opposite of the geographic (true north is south and vice versa)

Question 28

what protects us from radiation of the sun's solar wind

Answer 28

- Earth’s magnetic field protects us from solar wind—a stream of deadly charged particles emanating from the Sun—by deflecting it - charged particles that do get through are stopped by atmosphere

Question 29

aurora lights

Answer 29

The interaction of the solar wind with our atmosphere excites the nitrogen and oxygen, causing the aurora lights

Question 30

how we know the Earth is not hollow

Answer 30

- The passage of seismic waves shows no voids - The magnitude of our gravity requires a dense continuous interior to our planet - We have a magnetic field that can only be generated by a liquid iron core

Question 31

type of volcanic eruption that diamonds to the surface

Answer 31

Diamonds come from a rare type of volcanic eruption called a kimberlite eruption that brings them up within cooler surrounding rock at great speed before the magma can damage the diamonds.