earths structure

Question 1

why is interstellar space like a vacuum?

Answer 1

as it contains very little matter

Question 2

how does the geothermic gradient change?

Answer 2

depending on where you are on earth. differences in depth, change in pressure and temperature.

Question 3

what are seismic waves?

Answer 3

earthquake waves

Question 4

what is the epicentre?

Answer 4

the projection of the focus onto the surface of the earth.

Question 5

what are the 2 types of earthquakes which travel through solid earth?

Answer 5

P waves and S waves.

Question 6

what are the differences between P and S waves?

Answer 6

P waves are faster than s waves, they are compressional, analogous to sound waves and travel through solid and liquid. s waves (shear), hold the particle motion they don’t occur in liquids, and hence you can tell where liquids are.

Question 7

how can you use seismological evidence for the structure of the earth?

Answer 7

if no direct s waves, then there is no liquid in that pathway. you get some diffraction of p and s, and then in the middle- no longer transmits s waves. therefore, there is a liquid outer core.

Question 8

what is the earth made out of in terms of organic materials?

Answer 8

oil, protein, fat, rubber, carbon containing material.

Question 9

what is the earth made out of in terms of minerals?

Answer 9

solid substances in which atoms are arranged in an orderly pattern.

Question 10

what is the earth made out of in terms of glasses?

Answer 10

solid in which atoms aren’t arranged in an orderly pattern. glass forms when a liquid freezes so fast that atoms don’t have time to organise themselves.

Question 11

what is the earth made out of in terms of rocks?

Answer 11

aggregates mineral crystals or grains. sedimentary rocks or metamorphic rocks

Question 12

what is the earth made out of in terms of metals?

Answer 12

forms when solid material becomes hot and transform into a liquid.

Question 13

what is a sedimentary rock?

Answer 13

from from grains that break off pre-existing rocks and become cemented together.

Question 14

what are metamorphic rocks?

Answer 14

create when pre-existing rocks undergo changes such as growth of new minerals due to heat change or pressure.

Question 15

what is the earth made out of in terms of melts?

Answer 15

form when solid materials become hot and transform into a liquid. molten rock is a type of melt.

Question 16

what are the 4 classes of silicate rock?

Answer 16

Felsoc, intermediate, mafic, ultramafic.

Question 17

what are earths 3 distinct types of structures?

Answer 17

dry land, oceans and ice covered land.

Question 18

what is topography?

Answer 18

variations in elevation.

Question 19

what is earths layered interior?

Answer 19

crust (continental and oceanic), mantle (upper, transitional and lower), and core- outer liquid and inner liquid.

Question 20

what is the deepest anyone has drilled?

Answer 20

12 km in Russia. this is inly 0.03% of the earth.

Question 21

how do you measure the earths density?

Answer 21

find out the earth’s mass, by deflection of an object attached to a surveying instrument. the angle of deflection caused by the gravitational attraction of a mountain indicates the magnitude of gravitational attraction exerted by mountains mass relative to the gravitational attraction of earth mass.

Question 22

what is the continental crust?

Answer 22

underlies the continents. thickest is under mountain belt.

Question 23

what is Moho?

Answer 23

this is at the base of the continentl crust, which is a difference in density.

Question 24

what is the oceanic crust?

Answer 24

this is the crust which is much thinner and underlines the seafloor.

Question 25

what are “ophiolites”?

Answer 25

places where slices of the oceanic crust have been incorporated into mountians, and therefore exposed to air

Question 26

what layers do the oceanic crust have?

Answer 26

at the top there is a blanket of sediment- clay and tiny shells. beneath this, the crust holds basalt and gabbro.

Question 27

what is the difference in thickness between continental and oceanic crust?

Answer 27

continental is 5x thickness of oceanic.

Question 28

what are rifts?

Answer 28

plate motions can cause continents to stretch in narrow bands called rifts. the continental crust contains many rock materials.

Question 29

whare are the compositions in the crusts?

Answer 29

mafic, felsc in compisiotn, more felsic (granite) composition. oxygen is the most abundant elemnt 93 % of the crust.

Question 30

what is the mantle?

Answer 30

the mantle is the largest part of the earth in volume.

Question 31

how thick is the mantle?

Answer 31

3000km thick surrounding the core.

Question 32

whar are the 3 sublayers of the mantle?

Answer 32

upper mantle, transition zone and lower mantle.

Question 33

what is the mantle made of?

Answer 33

almost all solid rock. made up of entirely ultramafic rock- peridotite.

Question 34

why is it not all solid rock in the mantle?

Answer 34

so hot, that it is soft enough to flow very slowlu. therfore, mantle can change shape like wax

Question 35

what does the melt in the mantle cause to slow down?

Answer 35

causes seismic waves, to slow the melting down.

Question 36

why does convection occur in the mantle?

Answer 36

as it is hot and therefore it sinks and coolrock replaces its place.

Question 37

what is the core made out of?

Answer 37

iron alloys.

Question 38

why do earthquake waves bend pass the core?

Answer 38

cannot pass through the outer part of the core.

Question 39

what are the 2 areas of the core?

Answer 39

outer core and inner core

Question 40

what is the outer core made out of?

Answer 40

liquid iron alloy, with some iron, nickel, and solicon. its a liquid because the temperature is so high that even at great pressures, its not a solid.

Question 41

what is the inner core made of and why is it solid?

Answer 41

solid iron-nickel alloy. even though it is hotter than outer, the inner is solud due to being deoer and even greater pressure. restricts th movement.

Question 42

what is the atmosphere?

Answer 42

an envelope of gas.

Question 43

what is the atmosphere made out of?

Answer 43

78% nitrogen, 21% oxygen.

Question 44

what is the troposphere?

Answer 44

most winds and clouds in the lower level, air undergoes convection.

Question 45

what is the magnetic field?

Answer 45

is the region affected by the force emanatating from a magnet. this force grows progressively stronger as you appraoch the magnet (earth)

Question 46

why is the earth a magnet?

Answer 46

it is a large dipole, we can draw magnetic field lines. can attarct or repel another magnet and can cause charged particles to move.

Question 47

what is “magnetosphere”?

Answer 47

the region inside the magnetic field. without this shoeld, the solar winds would push radiation into the earths atmosphere.

Question 48

what does the solar wind do to the magnetosphere?

Answer 48

distorts it, its shaped like a teardrop, and forms a shield aroumd the earth, deflecting the solar wind and protects the earth.

Question 49

what are Van Allen belts?

Answer 49

concentrate the plasma coming from the sun. they consist of solar wind particles and cosmic rays nuclei of atoms that have been emitted during supernova explosions. they move so fast that they were able to penetrate the weaker part of the magnetic field. the expand and contract depending on the activities of the sun.

Question 50

how many van allen belts are there?

Answer 50

inner proton and electosn. outer- mostly electrons.

Question 51

what causes the northern lights?

Answer 51

magnetic field released by spectacular aurorae. some charged particles make it past the van Allen belts, and this causes the northern lights. the ionized atmospheric gases in polar regions cause it to glow.

Question 52

why are there 2 magnetic poles on earth?

Answer 52

the stronger the magnet, the greater its magnetisation. north and south, causes a dipole.

Question 53

why are there 2 norths?

Answer 53

due to the earths tilt, the planets rotational axis causes the compass to not point true north. the geographical poles of the planet dont coincide with the magnetic poles.

Question 54

what is magnetic inclination?

Answer 54

they dont stray more than 15 dgress off true north. the needles angle of tily is called magnetic inclination. the lines tilt at an angle to the surface at mid-latitude.

Question 55

what is basalt?

Answer 55

sark-coloured, magnetite-containing igneous rock that forms volanoes,

Question 56

is lava a magnet?

Answer 56

cools and solidified. when a volcano erupts, the lava is very hit and thermal energy makes its atoms wobble. each atom acts like a dipole. when this occurs, the magnetic force exerted by one atom cancels the force of another atom, so the lavas a whole isn’t magnetic. however, as the temperature decreases below the boiling point, basalt rock solidifies, as the magnetic crystals begin to form and cool, the dipoles become parallel with the earth’s magnetic field. the dipoles lock position, pointing in the direction of the magnetic pole, and it becomes a permanent magnet.

Question 57

how can you use basalt to predict where the earths magnetic pole was at the time of eruption?

Answer 57

the basalt provides a record for the orientation of the earth’s magnetic field lines, as the time which the rock cooled. this is called paleomagnetism.