Lecture 2

Question 1

What does geology mean

Answer 1

• geo means earth and logy means study

- >so study of the Earth

Question 2

Are there processes analogous to Earth’s processes around the solar system

Answer 2

• 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

Question 3

What are the three main types of rocks

Answer 3

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

Question 4

What is the law of origin horizontality

Answer 4

• 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

Question 5

What is the law of superposition

Answer 5

• 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

Question 6

What is the law of cross-cutting relationships

Answer 6

• 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

Question 7

What is the law of inclusion

Answer 7

-one rock is included in another is older than the rock that includes it

Question 8

What is the law of faunal succession

Answer 8

• as you get from older to younger rocks

- >you have a change in the organisms living in the environment

Question 9

Describe the three layers of the Earth’s interior

Answer 9

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

Question 10

Differentiate the asthenosphere from the lithospere

Answer 10

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)

Question 11

What is meant by the term subduction

Answer 11

• material goes down underneath
• > gets melting of asthenosphere portion
• > erupts or forms intrusions

Question 12

What is meant by the term divergence

Answer 12

• 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

Question 13

What is meant by the term rift zone

Answer 13

• 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

Question 14

Is the inside/core of the Earth more dense than the surface?

Answer 14

• 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

Question 15

What are seismic waves

Answer 15

• 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

Question 16

How does meteorites provide us with info about the Earth’s inner core

Answer 16

• 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

Question 17

Does the law of superposition, original horizontality apply to the mantle and lower layers of the Earth

Answer 17

-no because these layers are not sedimentary

Question 18

What does tectonics refer to

Answer 18

-it refers to the movement of the lithospheric plates

Question 19

Is the Pacific Plate(oceanic) subducting under the South American plate(continental)?

Answer 19

• yes
• > this is what produces the mountains that we see
• > because of the uplift of material that used to be down

Question 20

What is folding

Answer 20

• 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

Question 21

Do you see rift zones at divergent zones

Answer 21

• yes

- >for example, at the gulf of awaba and gulf of suezq

Question 22

What are volcanic eruptions made up of

Answer 22

• they are made up mostly of water vapor

- >and some CO2

Question 23

What is mass wasting

Answer 23

• 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

Question 24

Can volcanic related earthquakes lead to volcano walls collapsing

Answer 24

-yes

Question 25

Can mass wasting and volcanic activity be combined

Answer 25

• yes
• > because as landslides occur due to mass wasting, the sides of volcanoes can collapse and volcanic material can flow out

Question 26

Describe the dendritic drainage pattern of water

Answer 26

• it is the “tree like” movement of water

- >water branches off like trees

Question 27

What are point sources

Answer 27

• they are points where wind has enough energy to pick up dust/sand sitting there
• > and it continues to pick it up into billowing storms

Question 28

Describe the characteristics of an impact crater

Answer 28

• it is highly eroded
• > can be approximately 65 km in diameter
• sometimes they are just bowl-shaped
• > other times, they are bowl shaped but have a part in the middle, which rebounds back
• this part that rebounds back is called the central uplift
• > has a moat and the central uplift with the moat on the other side

Question 29

Describe 6 geological processes

Answer 29

1) Tectonic
- convergent margins/boundaries due to subduction
- >these margins result in mountain-building, faulting, metamorphism, and igneous activity
- divergent margins
- >result in faulting(some) and volcanic activity

2) Volcanic/igneous activity
- >you can get igneous activity from heat being released from the interior
- >don’t always need the interior

3) Mass Wasting
- >anywhere you have gravity material being pushed downwards

4) Agents of erosion
- >water
- >wind
- >ice

5)Activity of Life

6) Impact cratering process
- >external type of process where something from space come in and impact the surface