What does geology mean
- geo means earth and logy means study
- >so study of the Earth
Are there processes analogous to Earth’s processes around the solar system
- yes
- > eg; Saturn’s moon(Titan) and Pluto
- the cold liquids on the surface of Titan are methane and ethane as opposed to liquid water
- Pluto has flowing nitrogen ice(similar to but not the same as the flowing glacial ice on Earth)
- > this is because the temperature is so cold
What are the three main types of rocks
1) Metamorphic
- >changed through pressure and temperature in solid state
- >you can start with any other rock type
- >the change is from a solid state to another solid state
- >there is recrystallization/change in the minerals in the rock
2)Igneous
>solidified from molten
3) Sedimentary
- >formed by erosion, transported and deposited in sediments
What is the law of origin horizontality
- sedimentary layers are deposited horizontally
- layers are horizontally continuous
- > the way that water/ice transports the sediments is not in a block formation
- > it is horizontally continuous
What is the law of superposition
- in a sequence of sedimentary rocks, each layer of rock is older than the layer above it
- > and younger than the layer below it
-note this law is applicable to any rock layers deposited at the surface
What is the law of cross-cutting relationships
- if a fault or a body of rock cuts through another body of rock
- > then that fault must be younger than the rock through which it cuts
-note if the lave flow cuts through the fault, it is younger than the rock layer it cuts through
What is the law of inclusion
-one rock is included in another is older than the rock that includes it
What is the law of faunal succession
- as you get from older to younger rocks
- >you have a change in the organisms living in the environment
Describe the three layers of the Earth’s interior
1) Crust
- outermost layer on top of mantle
- different composition from the mantle
- >the boundary between the mantle and the crust is the compositional difference
- note the crust can be oceanic and continental
2) Mantle
- >there is an upper and lower layer
- >includes the asthenosphere
- >has iron and magnesium minerals
- >eg; olivine and pyroxene
3) Core
- >mostly iron metal(very dense)
- >solid inner, liquid outer
Differentiate the asthenosphere from the lithospere
Lithosphere
- > includes the rigid part of the mantle and the overlying crust
- > ten to several hundred km thick
- > rides on plastic asthenosphere, causing plate tectonic movement
Asthenosphere
- > the top part of the upper mantle(10-250 km)
- > it is weak(plastic and able to flow)
- > note it is partly molten
- note the asthenosphere is not a magma body
- > it is not completely molten/liquid
- the source of magma ascends into the crust and may erupt on the surface(volcanic activity)
What is meant by the term subduction
- material goes down underneath
- > gets melting of asthenosphere portion
- > erupts or forms intrusions
What is meant by the term divergence
- plates pull apart
- > new crust is being created
- parts close to the surface and are close to their melting point will partially melt
- > they cool and then become new crust
What is meant by the term rift zone
- rift is a part of the continental crust
- >this is where new crust is formed by sediments and magma coming in and filling it in
Is the inside/core of the Earth more dense than the surface?
- yes
- > something has to exist that will make it heavier
- surface densities are smaller than the average bulk density
- > mantel is like an average
- > the core is very dense
What are seismic waves
- waves of energy from earthquakes
- velocities of the waves change
- > this depends on the rigidity and density of the layers
- in a liquid, S waves are not transmitted but P waves are
- > therefore, S waves will not go through the liquid outer core
- > note that P waves slow down in the outer/inner core
- S waves can go through the solid inner core because P waves can convert into S waves
- both waves slow down in the asthenosphere
How does meteorites provide us with info about the Earth’s inner core
- iron meteorites thought to represent fragments of the core of a now-disrupted planetary body
- stony meteorites thought to represent the mantle of the body
- by analogy, the Earth must have an iron-rich core and a stony mantle
Does the law of superposition, original horizontality apply to the mantle and lower layers of the Earth
-no because these layers are not sedimentary
What does tectonics refer to
-it refers to the movement of the lithospheric plates
Is the Pacific Plate(oceanic) subducting under the South American plate(continental)?
- yes
- > this is what produces the mountains that we see
- > because of the uplift of material that used to be down
What is folding
- as plates collide(tectonic activity)
- > the rocks are squeezed and become deformed in a way that is plastic
- > it allows them to change direction and orientation
-note folding follows the law of original horizontality
Do you see rift zones at divergent zones
- yes
- >for example, at the gulf of awaba and gulf of suezq
What are volcanic eruptions made up of
- they are made up mostly of water vapor
- >and some CO2
What is mass wasting
- the action of gravity to cause landslides, rockfalls, etc
- > any downfall movement
- > the water percolates into the rocks on the side of the volcano
- > water vapor weakens the volcano walls, which can cause landslides
-mass wasting varies from planet to planet due to differences in gravity
Can volcanic related earthquakes lead to volcano walls collapsing
-yes
