science 3

Question 1

who first posed the theory of continental drift and when

Answer 1

Alfred Wegener

Question 2

what is the theory of continental drift

Answer 2

a theory that all the continents were connected to each other and then drifted away

Question 3

what is seafloor spreading

Answer 3

the formation of fresh areas of oceanic crust which occurs through the upwelling of magma at mid-ocean ridges and its subsequent outward movement on either side.

Question 4

how old is the sea floor

Answer 4

the oldest seafloor rocks found were 200million years old

Question 5

how do tectonic plates move

Answer 5

through currents on the mantle

Question 6

from core outwards, name the different layers

Answer 6

the inner core, outer core lower mantle, upper mantle, crust, lithosphere

Question 7

how thick is the crust

Answer 7

up to 75 km thick

Question 8

name the types of crust

Answer 8

oceanic crust and continental crust

Question 9

what is the oceanic crust

Answer 9

the crust found on the ocean floor

Question 10

what is the continental crust

Answer 10

the crust that forms continents

Question 11

which is denser oceanic crust or continental crust

Answer 11

oceanic crust because it contains less silicon and more iron and magnesium

Question 12

which is thicker oceanic crust or continental crust

Answer 12

continental crust

Question 13

what are the 3 types of tectonic plate movement at boundaries

Answer 13

diverging, converging, transform

Question 14

what is a diverging tectonic plate movement

Answer 14

where plates are moving apart from each other. this often leads to magma rising from the gap, cooling, and creating new crust.

Question 15

what is a converging tectonic plate movement

Answer 15

when 2 plates collide with each other. this creates volcanoes. these are also known as destructive boundaries.

Question 16

what is a transform tectonic plate movement

Answer 16

is where two plates are sliding parallel to each other but in opposite directions. when this happens there is an earthquake.

Question 17

what is magnetic striping

Answer 17

Magnetic Striping. Magma contains many materials which are magnetically affected. When this magma is ejected from the mantle and begins forming a new crust, these materials align to the earth’s magnetic field. The crust hardens, and the magnetic alignment is fixed (just as in normal magnets, made by using a similar process).

Question 18

what has the old pre-continental drift land mass been named.

Answer 18

Pangaea

Question 19

Pangaea gradually broke into two major landmasses: ____ in the north and ____ in the south.

Answer 19

Laurasia, Gondawa

Question 20

what are explosive eruptions

Answer 20

subduction, generates heat, melting rock and forming magma. The magma rises up in huge packets through lines of weakness in the crust. It accumulates in spaces called magma chambers and is occasionally released to the surface as the pressure builds up.

Question 21

What causes an earthquake

Answer 21

It is caused by the rapid release of energy as the tectonic plates move. friction between the plates must be overcome before they can move. when the force is great enough, the plates suddenly move as friction can no longer hold them.

Question 22

how would one detect an earthquake

Answer 22

Earthquakes are measured using an instrument called a seismometer.

Question 23

how did scientists find out about seafloor spreading

Answer 23

In 1872, scientists were surveying for an undersea cable, They did this by dropping down very long cables and measuring their length. they discovered a large mountain ridge in the middle of the Atlantic Ocean. The ridge was found to extend a long way in the South Atlantic, but the extent of the ridge was not investigated.

Question 24

when did Alfred Wegner think of his theory of continental drift?

Answer 24

1912

Question 25

what were the two premises of Alfred Wegener’s continental drift

Answer 25

that the continents fitted together like a jigsaw and that there were organisms spread across different continents that are known to not be able to travel that far.

Question 26

why was Wegner’s theory widely disputed by scientists

Answer 26

because there was no known mechanism that would allow continents to move.

Question 27

what are the 2 things that led to Hess’s theory

Answer 27

Flat-topped mountains in the south pacific and undersea mountains

Question 28

how many large tectonic plates are there

Answer 28

7

Question 29

how many medium tectonic plates are there

Answer 29

10

Question 30

how many small tectonic plates are there

Answer 30

60

Question 31

how are ocean currents affected by tectonic plates

Answer 31

crust splitting often leads to create new currents

Question 32

how are flora and fauna affected by continental drift

Answer 32

the isolation of flora caught between the rift of continents leads to unique species of the previous plants.

Question 33

what is a diverging plate movement known for doing

Answer 33

it is known for creating new crust through the release of magma.

Question 34

what is a converging plate movement known for doing

Answer 34

it is known for making subductions that create volcanoes.

Question 35

what is a transform plate movement known for doing

Answer 35

it is known for creating earthquakes.

Question 36

why is the crust moving

Answer 36

because of sea floor spreading