plate tectonics

Question 1

give 3 facts about the core

Answer 1

1. made of dense iron and nickel alloy
2. outer core is molten (5000 degrees)
3. 5100km deep

Question 2

what is primordial heat?

Answer 2

heat remaining from the earths formation

Question 3

what is radiogenic heat?

Answer 3

heat from decaying isotopes

Question 4

what 2 ways heats the core?

Answer 4

1. primordial heat
2. radiogenic heat

Question 5

give 3 facts about the mantle

Answer 5

1. the thickest layer
2. 2900km deep
3. made up of molten and semi molten rock

Question 6

what is the athenosphere?

Answer 6

the fluid, upper part of the mantle which the lithosphere sits on

Question 7

give 4 facts about continental crust

Answer 7

1. 30-70 km deep
2. 1500m + years old
3. 2.6 density
4. composed of granite, alluminium, silicon and oxygen

Question 8

give 4 facts about oceanic crust

Answer 8

1. 6-10km deep
2. less than 200m years old
3. 3.0 density
4. composed of basalt, silicon, magnesium and oxygen

Question 9

what is paleomagnetism?

Answer 9

a record of the earths magnetic field preserved in magnetic minerals

Question 10

what does the plate tectonic theory state?

Answer 10

the theory the earth is made up of 7 rigid plates which all move

Question 11

who discovered the Pangea theory?

Answer 11

Alfred Wegener

Question 12

what is Pangea?

Answer 12

a theory of a supercontinent 300 million years ago

Question 13

how did pangea split?

Answer 13

through continental drift

Question 14

what is a plume?

Answer 14

a hot column of magma that arises from deep in the earth

Question 15

what is a rift valley?

Answer 15

a long deep valley found at a fault line

Question 16

what is a fault line?

Answer 16

a crack in the earth caused by tectonic movement

Question 17

what is sea floor spreading?

Answer 17

the theory that the ocean floor is moving away from the mid oceanic ridge

Question 18

what is a mid oceanic ridge?

Answer 18

an underwater mountain range where the crust is activiely spreading apart

formed via plate tectonics

Question 19

give 3 pieces of geological evidence for continental drift

Answer 19

1. jigsaw fit between continents e.g South America and West Africa
2. similar glacial deposits in sotuh africa, india and antartica
3. similar rock sequences in north scotland and east canada

Question 20

give 2 biological reasons for continental drift

Answer 20

1. fossils in india are similar to those in Australia
2. identical plant fossils in india and antartica

Question 21

what is the lithosphere?

Answer 21

the combination of the crust and upper mantles

Question 22

what does the plate tectonic theory suggest?

lithosphere and athenosphere

Answer 22

the lithosphere can slide over the athenosphere to create plate movement

Question 23

what occurs to counteract sea floor spreading?

Answer 23

subduction in ocean trenches to destroy crust

Question 24

what are convection currents?

Answer 24

heat driven cycles which support the movement of lithospheric plates

as well as causes ridge push and slab pull

Question 25

what is ridge push?

Answer 25

at constructive plate boundaries, oceanic ridges create a denser lithosphere, causing it to slide on the sloped athenosphere through gravity.

Question 26

what is slab pull?

Answer 26

at destructive plate boundaries older, colder oceanic plates are denser than the underlying mantle, causing it to subduct through gravity | the force on the sinking edge is known as slab pull

Question 27

what are ocean trenches?

Answer 27

subduction of an oceanic plate causing a trench

Question 28

what are young fold mountains?

Answer 28

where settlement is accumulated on the continental plate during subduction and is then folded and uplifted

Question 29

what is a hot spot?

Answer 29

an area of crust heated by a mantle plume away from a plate boundary

Question 30

how do island arcs form?

Answer 30

as tectonic plates move over hotspots, it takes the previously formed volcanic island with it, creating another volcanic island. | eventually causing a curved chain