Zusammenfassung der Ressource
Geology - 1.1
- 1.1.1
- Asteroids
- Collisions happen which creates
meteorites
- Large rocky objects left
over from the formation of
planets
- Planets
- Terrestrial
- All have similar characteristics, All 'Earth Like'
in structure
- formed in a similar
way to Earth
- Mercury, Venus, Earth, Mars
- Gas Giants
- Jupiter, Saturn, Uranus, Neptune
- All made of
Gas
- Origins
- Big Bang = 14billion
yrs ago
- Formed when a giant molecular cloud of gas
and dust collapsed. Eventually formed was a
rotating disc material was drawn towards the
centre, it triggered nuclear reactions=Sun's
formation, dust particles began to stick
together (accretion), forming larger objects,
finally resulting in planets
- Solar System = 4500million yrs ago
- 1.1.2
- Types
- Iron
- Composed of alloy of
iron and nickel, 6% of
known meteorites
- core of a small
plant-like object
- Stony
- Composed of silicate
minerals
- mantle of a small
plant-like object,
- Carbonaceous chondrites
- contains water
and organic
compounds
- Similar to
composition of
the sun but with
fewer volatiles
- Impact Craters
- Formation
- • Material to
be ejected
and quartz
grains to be
violently
shocked and
even melted
• Rock strata
to be tilted
• Material at
depth to be
broken
up• The
ejected
material falls
back to the
surface
inverted
- Evidence
- • Vaporisation and
partial melting of
host rock • Seismic
activity • Giant
tsunamis
• Wildfires • Dust in
atmosphere =
global cooling and
ecosystem collapse
- Found more
commonly in the
deserts and antarctic
- Mostly from the
asteroid belt
- Volcanic Activity
- Seen on Mars and
Venus in a similar
way to Earth's
volcanos, as similar
structure
- Gas Giants Moons,
tidal heating =
volcanism
- Dating Planets
- Can't be measured directly as
surface was originally molten
- Erosion and other processes have
dystroyed the old rocks
- 1.1.3
- The inner core from the
centre- 6371km -5100m:
The inner core is made
of a solid material due to
extreme pressures,Both
P and S waves travel
through, Mix of iron and
nickel, based on
meteorites evidence and
the idea of correct
densities.
- Lehmann Discontinuity at 5100km: Phase
boundary. Zone of about 100km where
material changes state
- OUTER CORE from 5100km to
2900km: Liquid iron and nickel ,
S waves can’t travel through. P
waves slow down due to
reduction in rigidity. Pressure in
the outer core
- Lower mantle from 2900km to 700km:
Solid as S waves can travel through it, P
waves increase steadily in velocity
because of its pressure,Same type of
silicate found in stony meteorites
- Upper mantle from 700km to an average of 35km: Contains
solid silicates but less dense than lower mantle, Main rock is
Peridotite, Consists of the asthenosphere and lithosphere
- Gutenberg
discontinuity at
2900km: Boundary
marking a change
in material from
metallic iron nickel
to stony silicate.
Also changes state.
P waves velocity
decreases, S waves
stop
- The Asthenosphere: A layer of soft but solid rock
mobile rock, with high 'plasticity', comprising the
lower part of the upper mantle from about 100 to 200
(up to 350 kilometers) beneath the Earth's surface.
- The Lithosphere: A layer of solid, brittle rock making up the outer
100 kilometers of the Earth, encompassing both the crust and the
outermost part of the upper mantle.
- 1.1.4
- Volcano’s bringing magma from depth
- Carries up rock from these layers
from depth
- Basalt layers which erupt at
mid-ocean ridges - partial melting
of the upper mantle
- Kimberlite pipes are results of
explosive volcanism from deep
mantle sources.
- Xenoliths (foreign rocks
in magma)
- Mines and Boreholes
- Boreholes go further but people
cannot go in them
- Direct access to the higher
levels of the crust by
mining/digging
- Mines become too hot to be in,
with little ventilation to go any
further
- Geothermal Gradient
- Rate of increase in
temperature per unit of depth.
- Temp gradient is lower in the mantle
because of the radioactive heat
production is concentrated in the crust,
thermal transport changes from
conduction to convection on the
asthenosphere and upper mantle and
this transports the heat differently
- The Crust
- Geological maps show what things
look like but with some debate
over detail. show varied continetal
crust materials
- Ophilite Suites
- During the collisions, continental plate that has
broken off may be thrust onto the oceanic plate
instead of going into the mantle, 7km thick
- 1.1.5
- Shadow Zones
- P and S Waves: 142 degrees
from the epicentre and
103 degrees from the
epicentre
- S Waves: 103 degrees
from the epicentre and
103 degrees from the
epicentre
- Seismic Activity
- Body Waves- travel faster if rock is
more rigid and incompressible and
slower if more dense ● S Waves -
only liquid zones ● P waves - solid
and liquid zones
- Seismic Reflection: ● Return of
some energy to the surface from
a boundary of two layers of
differing density
- Seismic Refraction: ● Occurs if
velocity differs in each layer caused
by density differences ● Bending of
waves
- Densities
- Earth density =
5.5 g/cm cubed
- Oceanic crust= 2.9 g/cm cubed
- Continental crust =
2.7 g/cm cubed
- Meteorites
- similar compositions to our
mantle and core
- Iron me. are more
dense 7-8g/cm3
- Stony me. are
more dense
3-3.7g/cm3
- 1.1.6
- Apparent Polar Wander Curves
- The continents move so it looks as
if there are 2 pole although not.
- Variation in the field
- field fades over several thousands of
years it then increases again but with
inverted poles
- Evidence = Remnant magnetism: is
magnetism shown by rocks due to
the alignment of their magnetic
minerals according to the Earths
magnetic field at the time of their
formation
- Magnetic Inclination
- latitude of a volcano at the time it erupted its
lavas by using the magnetic inclination
- is the angle of dip of the lines of a
magnetic field. It is the angle with the
horizontal made by a compass needle
- Origins of the earth’s magnetic field
- liquid core causes the magnetic field. The
convecting mass of molten Fe will make
electricity, which induces magnetism (which
repeats).
- generation and destruction allows the earth to
show a weak continuous magnetic field
- Curie point - where a rock loses magnetism so
not permanent and constantly changing in earth
- Magnetic reversals and palaeomagnetism
- Iron rich minerals in lavas align
themselves with the earths
magnetic field
- Cool through the curie point and retain there magnetism
permanently
- Act like frozen compasses showing the
direction of the poles at the time of there
formation