introducing planet earth

Question 1

the solar system

Answer 1

a group of celestial bodies including earth orbiting around and gravitationally bound by the star known as the sun

Question 2

Name the 8 planets

Answer 2

1) mercury
2) venus
3) earth
4) Mars
5) jupiter
6) saturn
7) uranus
8) neptune

1-4 - terrestial planets
5-8- icy planets

Question 3

name the 3 dwarf planets

Answer 3

Pluto , Eris , ceres

Question 4

define asteroids

Answer 4

rocky, metallic objects that orbit around the sun in the asteroid belt between mars and Juoiter

Question 5

define comets

Answer 5

small, icy bodies that orbit around the sun

Question 6

meteoroids

Answer 6

small bodies that travel through space - stony and metallic - smaller than ase

Question 7

name earth’s inner structure

Answer 7

the crust
the mantle
outer core
inner core

Question 8

name the characteristics of the crust

Answer 8

the thinnest layer
comprised of 2 types of crusts;
1) continental crust
2) oceanic crust

the continental crust - solid layer of rocks that make up the continents and continental shelves (shallow seabed close to shore )
the oceanic crust -part of Earth’s crust that forms the ocean bed
most common elements ; oxygen , silicone , aluminium ,

the continental crust - older , lighter ,cannot sink and is permanent
the oceanic crust ; carries water ; younger , heavier , can sink - constantly being destroyed and replaced

Question 9

Characteristics of the mantle ;

Answer 9

a thick layer . Made up of oxides of silicone and magnesium . Earth’s internal heat is found here
the mantle can be divided into 2 ;
outer mantle ; consists of a solid layer below which is a layer of sow flowing molten rock in a plastic state
inner mantle - solid because of high pressures

Question 10

characteristics of the core ;

Answer 10

outer core ; a dense liquid layer - composed mainly of molten iron and nickel - controls Earth’s magnetic fields
Inner core - solid mass - nickel and iron alloy

Question 11

the lithosphere

Answer 11

includes the crust and the rigid upper part of the mantle -
the mohorovicic discontinuity - separation between crust and upper mantle-
strongest layer because it is relatively cool since it is so close to the surface
not a continuous layer but formed of plates
- 8 large plates that move constantly supported by the flowing asthenosphere

Question 12

the asthenosphere

Answer 12

part of the upper mantle that exhibits plastic properties -located below lithosphere

Question 13

how many large plates and how do they move ?

Answer 13

1) six large plates

2) They move horizontally and vertically - continuous motion driven by the convention currents

Question 14

plate tectonic theory

Answer 14

explains the movement of earth’s crust throughout the geologic time producing continental drift that has resulted in present-day positions of the continents . it also explains the locations of mountain building, earthquakes and volcanoes

Question 15

the current continental and oceanic plates ;

Answer 15

The Eurasian plate, Australian Indian plate , philippine plate, Juan De Fuca plate, Nazca plate , Cocos plate , North American plate, caribbean Plate, south american plate , African plate , arabian plate , antarctic plate and scotia plate

Question 16

plate boundaries -

Answer 16

edges of lithospheric crust where plates interact with other plates hence earthquakes volcanic activity
also mountain building and ocean ridges formation occur here

Question 17

3 types of plate boundaries ;

Answer 17

divergent boundaries
convergent boundaries
transform boundaries

Question 18

divergent boundaries- mid -ocean ridges

Answer 18

when 2 plates separate , the space created between them is filled by magma which solidifies to form basalt - new rock is formed
mid-ocean ridges are underwater mountain ranges formed as magma frim asthenosphere is forced through a crack in the oceanic crust and cools . this causes new oceanic crust - sea - floor spreading
example - MId-atlantic ridge - north american plate and eurasian plate

Question 19

sea-floor spreading

Answer 19

movement of 2 oceanic plates away from each other -formation of new oceanic crust - zone of divergence

Question 20

a divergent boundary involving two continental crusts

Answer 20

for example - african plate that is diverging from the arabian plate giving rise to the red sea

Question 21

convergent boundaries

Answer 21

occur at collision zones where plates are moving towards one another - volcanism and earthquakes

Question 22

name the 3 types of collisions

Answer 22

1) oceanic plate and continental plate
2) two oceanic plates
3) two continental plates

Question 23

oceanic plate and continental plate collision

Answer 23

two plates push against each other until the denser plate (oceanic plate) is forced into the mantle - generate earthquake activity . As the ocean plate sinks into the mantle , parts of it may melt and form magma. This magma travels upward and encounters the overlying continental crust forming a volcano .

Question 24

what happens when a plate with oceanic crust is forced against another plate with oceanic or continental crust

Answer 24

a subduction zone occurs which is forced into the asthenosphere- the subducting slap enters at an angle which gives rise to a trench

Question 25

what is a significant characteristic of the convergent boundaries

Answer 25

when the 2 plates collide , the sediments situated between them are upthrust to form a mountain range and orogery (mountain range

Question 26

Two oceanic plates

Answer 26

one may be pushed under the other and magma from mantle rises ,forming volcanoes in vicinity

Question 27

two continental plates

Answer 27

when 2 continental plates collide ,mountain ranges are created as the colliding crust is compressed and pushed upwards- the Himalayan mountain range

Question 28

conservative boundaries

Answer 28

they don’t involve the creation or destruction of plate material . The two plates slide past eachother (same or opposite direction )

Question 29

Earthquakes

Answer 29

The shaking and vibration of the Earth’s crust due to the movement of earth’s plate (sudden release of accumulated strain )
friction prevents rock on both sides of a fault form slipping , but when the force is acting on the rock exceeds the frictional resistance the sides move suddenly

Question 30

why do the plates move?

Answer 30

they move because of convention currents as a result of the very high temperature in the inner core

Question 31

what happens when the plates pass past each other?

Answer 31

stress is created , the crust will break forming a fault -
when the break occurs , the stress is released as energy that moves through the earth in the form of a seismic wave
Earthquakes can occur at all boundaries especially at convergent and conservative boundaries

Question 32

where are earthquakes most common

Answer 32

circum pacific seismic belt - ring of fire

the Mediterranean and trans-Atlantic belt which extends froms

Question 33

the focus

Answer 33

the point below earth’s surface at which the earthquake originates (point of initial movement)

Question 34

epicentre -

Answer 34

the point on the surface directly above the focus - most severe damage

Question 35

what can an earthquake be measured by ?

Answer 35

intensity and magnitude

Question 36

intensity

Answer 36

intensity assesses the strength of shaking produced by an earthquake at a certain location - determined by effects on people , building and infrastructure and natural environment - can be subjective and intensity scales are useless in inhabited areas- Mercalli scale

Question 37

Magnitude

Answer 37

calculates the amount of energy release at the source of earthquakes -seismographs - measure size of seismic waves-ritcher scale - logarithmic scale -

Question 38

primary effects of an earthquake

Answer 38

caused directly by the ground shaking and breaking in more severe cases - severe damage to building and infrastructure

Question 39

secondary effects

Answer 39

consequences of primary effects - can cause more loss of life than primary effects - landslide fires , floods etc

Question 40

Tsunami -

Answer 40

a particular secondary effect - created by sudden displacement and underwater volcanic eruptions - they star as shallow waves with a long wavelength - they move at very fast speeds from epicentre. Close to shore the waves slow down and rapidly gain height