3: Earth History Flashcards
1
Q
What are original remains?
A
Organisms that have been ambered in stone.
2
Q
What is the mnemonic to remember the order of the geological time scale?
A
Cold Oysters Seldom Develop Many Precious Pearls, Their Juice Conceal Too Quickly
2
Q
What is angular disconformity?
A
When new rock deposits on top of an old rock that has been tilted. Where the old jagged rock and the new horizontal rock join, this is called the angular disconformity.
3
Q
What is the principle of original continuity?
A
When rocks are separated by a large basin, even though there is a large gap between layers, they are still the same layer.
4
Q
What is an epoch?
A
Smallest divide of time in comparison to others (i.e.: Era/Period, etc)
4
Q
What is the principle of succession?
A
When forming rocks, they form one on top of another with the eldest at the bottom and the youngest at the top.
5
Q
What does mya mean?
A
A million years before the present time.
5
Q
What is a classic example of a place where the rocks may have taken a million years to develop?
A
Grand Canyon
5
Q
What are the key points of an angular disconformity?
A
- The old rock is not horizontal, it is jagged
- The new rock forms in parallel and horizontal layers.
6
Q
What are the 5 steps to relative dating?
A
- Principle of Superposition
- Principles of Original Horizontality
- Principle of Cross Cutting
- Principle of Original Continuity
- Principle of Faunal Succession
7
Q
What are the 4 eons the geological time scale is separated into?
A
Precambrian, Paleozoic, Mesozoic, and Cenozoic.
8
Q
What are the name(s) of the eons?
A
Proterozoic Era, Mesozoic Era, Cenozoic Era (current era)
9
Q
What are casts and molds?
A
These are usually caused by organisms that have hard shells or the like. The underlayer is usually very soft, so when the shell or the bones sit on top, they create a mold. Then, the soil hardens giving time for the shell to disintegrate. It will then be filled with minerals, and the like.
10
Q
What is an eon?
A
A large period of time where there was a mass extinction
12
Q
What are the 3 stages that are under precambrian?
A
Hadean, Archean, and Proterozoic
13
Q
How long ago was the Earth created?
A
4.55 billion years ago
13
Q
What is catastrophism?
A
The thought that everything on Earth was created by some supernatural force of power.
14
Q
What does the mnemonic stand for?
A
Cambrian, Ordovician, Silurian, Devonian, Mississipian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Tertiary, Quaternary
15
Q
Why do varves occur more often in freshwater lakes than saltwater lakes?
A
Saltwater Lakes tend to cause a homogenous mixture of the substance (uniform).
15
Q
What happens to varves in the summer months?
A
Water and sediment take up more room. They are usually a lighter colour. The amount of sediment flowing back and forth is relatively large.
16
Q
What is nonconformity?
A
When the igneous or the metamorphic rock is exposed to the surface, a new layer of rock forms on top of it. Where the igneous/metamorphic rock meets the new rock, is known as nonconformity.
18
Q
What are the 5 types of fossils?
A
- Original Remains
- Casts and Molds
- Carbonization
- Permineralization
- Trace Fossil
20
Q
What happened during the Cenozoic Era?
A
Lots of mammals
21
Q
What are 2 things that eras are separated by?
A
Time and structure of organisms
22
What is the principle of cross cutting?
Faults are caused by intrusions or earthquakes. The rock layers that surround this intrusion are older than the fault itself.
23
What are the key points of nonconformity?
1. The contact between new and old rock is formed in parallel layers.
24
What are varves?
Layers that have deposited in one year. They usually occur in freshwater lakes rather than saltwater lakes.
25
What happened during the Proterozoic Era?
Happened 248 million years ago with extinction of 90% of Marine Animals
26
What are the key points of disconformity?
1. Disconformity: Boundary between old rock and new rock
2. Contact between the old and new rock is an irregular surface
27
What is disconformity?
The youngest horizontal layers erode, revealing the older layers. New rock is then deposited. Where the old and the new rock join, this is known as disconformity.
29
What type of thing was very prevalent at the end of the Hadean time?
Bacteria
30
What happened during the Mesozoic Era?
The Dinosaurs were all killed due to a meteorite impact.
31
What was Hutton's evidence?
Geological processes that he witnessed were so complex that it would not be able to form in a short amount of time.
32
What is one thing that varves may tell us about the temperature of a certain time period?
The thickness of layers can help determine the temperature or the climate of a certain time period. A very thick light coloured layer would then represent a very long and warm summer.
33
What is the principle of original horizontality?
The Principle of Superposition relies very much on this principe which says that when the Earth's Crust shifts the different layers, it may look like it is not horizontal. However, when it was first deposited and created, it was.
34
What are the characteristics for a good fossil?
1. Wide Distribution of Fossil
2. Fossils are abundant
3. Fossil appears in a narrow time span
36
When did mammals first appear?
Triassic Period
38
What did William Whewell do?
Claimed Hutton's observations at "uniformitarianism".
39
What is the KT boundary?
The time period in which the dinosaurs roamed the land and the Earth to when there were terrestrial mammals walking about.
40
What are the three types of unconformities?
1. Disconformity
2. Angular Disconformity
3. Nonconformity
41
Who suggested that the Earth was much older?
James Hutton
42
What happens to varves in the winter months?
The flow is reduced significantly because they are all frozen. Also, the particles are usually much darker.
43
Name 2 epochs:
Either:
* Holocene
* Pleistocene
* Pilocene
* Miocene
* Oligocene
* Ecoene
* Paleocene
44
What is the principle of faunal succession?
The evolution and extinction of life has produced many different distinct fossils. The age of the rock can help determine the age of fossils. You would only find organisms or fossils that pertain to that time period.
45
When was cyanobacteria start forming?
Archean and Proterozoic
46
What are the 5 main pieces of evidence that supports Pangaea?
Perfect puzzle, fossils, fossilized bones, tillite, and mountain ranges.
47
How can paleoclimates be measured?
Ice, dendroclimatology, and fossils and living organisms.
48
What is the role of ice in paleoclimatology?
The materials inside the core allow us to estimate the chemical composition at that point in time.
49
What is the role of dendroclimatology in paleoclimatology?
It is the measuring of tree rings and the age of trees. It can help determine precipitation and many other things.
50
What is the role of fossils and other organisms in paleoclimatology?
The species can change based on the temperature.
51
What are the main things that happened during the Precambrian Period?
* Harsher Climate
* Global temperature were much warmer
* "Snowball Earth" at the end of the period.
52
What are the main things that happened during the Paleozoic Climate?
* Ice sheet covered most of Gondwanaland.
53
What are the main things that happened during the Mesozoic Era in paloeclimatology?
* Climate stayed relatively warm
* Warmed a lot in the first Cretaceous period
* Temperature differences in poles were very small
* End of Mesosoic Era - cooled down
* Asteroid Impact
* Volcanism
54
What are the main things that happened during the Cenozoic Era related to paleoclimatology?
* Relatively cool in comparison to the rest of the Earth
* Multiple ice ages in the last 2 mya
* Most of the ice sheets melted 100 000 years ago.
55
What is the thing that Milankovitch is trying to explain?
Cyclic "rotation" or changing of glaciers.
56
What are Milankovitch's 3 main points?
* Eccentricity
* Axial Tilt
* Precession
57
What is eccentricity?
The Earth's orbit is not entirely circular, it is often changing between elliptical and circular.
58
What happens when the earth's orbit is more circular?
The season conditions in both regions wil be relatively the same.
59
What happens when the earth's orbit is more elliptical?
There will be significant differences in temperature (ie: one will have very hot summers and very cold winters while the other will have mild summers and winters).
60
What is axial tilt? What is another name for it?
Synonym: Obliquity
What is it? The tilt of the Earth going around the Sun changes, so the amount of Sun coming into Earth's atmosphere also changes.
61
What happens when the axial tilt is at its maximum?
More solar radiation entering the earth causing more extreme weather conditions (hot summers and cold winters).
62
What happens with axial tilt is at its minimum?
Summers and winters are both relatively cool.
63
What is precession?
When the earth rotates around the sun, it also turns on its own axis. However, it creates a bit of a wobble while it is doing this.
Precession measures the distance between the Earth and stars that are in fixed locations (Polaris).
64
What will a decrease in carbon dioxide cause?
* Global temperatures increase due to the abundance of carbon dioxide
65
What will an increase in oxygen cause?
* Increase in ice
* Glaciers could move ~ 30 degrees
* Caused Ice Ages
66
What will an increase in carbon dioxide cause?
* Warmer air temperature
* Warmer water temperature
* Lot less oxygen in water
* Less water in regions around the equator
* Less currents
* Atmosphere rich in carbon dioxide and hydrogen sulphide.
67
What are 3 types of plate boundaries?
Divergent Boundary, Covergent Boundary and Transform Boundary
68
What is a divergent boundary?
Two plates are moving apart. As the plate moves, magma from under the rock seeps upward. It ends up restrengthening the plate.
69
What is a covergent boundary?
When 2 plates move towards each other.
70
What are the 3 types of covergent boundaries?
1. Oceanic Plates and Continental Plate moving towards each ohter
2. Two Oceanic plates
3. Two Continental Plates
71
What happens when an oceanic plate and a continental plate move towards each other?
The ocean plate slips below the continental plate, which causes mountain formation on the continental plate and trenches on the ocean plate.
72
What is a subduction zone?
When an ocean plate descends below a continental plate.
73
What happens when two oceanic plates move towards each other?
They form very deep trenches. There is usually evidence of volcanoes, islands, or arcs.
74
What happens when two continental plates move towards each other?
Both rocks push upwards creating mountain ranges.
75
What is a transform boundary?
When 2 plates slide past each other.
76
What is relationship between plate tectonics, earthquakes and volcanism?
Almost all of the earthquakes and volcanoes are situated on the boundaries of plate tectonics or on faults within the plate.
77
What are the 3 processes that can move plate tectonics?
Mantle Convection, Slab Pull, Ridge Push
78
What is mantle convection?
Magma is extremely hot and dense, causing it to rise to the surface. It brings the plate tectonic along with it. When convection currents come along, the water rises in the middle, cools then sinks to the bottom.
79
What is ridge push?
When magma rises in the mid-ocean ridges (when it is not). Gravitational forces cause it to slide away from the ridge, pushing the oceanic crust on a lower slope.
80
What is slab pull?
On the boundary of a subducting plate, it is often cooler and heavier than the mantle. When it sinks, the plate is pulled along with it. Eventually, the subducting plate will pull the continental plate from the table.
81
What is seismology?
Study of earthquakes and after-quakes and seismic wave activity through the earth.
82
What are the 2 types of seismic waves?
Body waves and surface waves
83
What are body waves?
These are waves that travel through and under the earth's crust.
84
What are 2 types of body waves?
Primary waves and secondary waves.
85
What are primary waves? What are their characteristics?
They travel through both liquids and solids. They are often compressional.
86
What are secondary waves? What are their characteristics?
They can only travel through solid rock.
87
What are surface waves?
The body waves reach the surface of the earth and then radiate outwards. After an earthquake, most of the damage is caused by this type of wave.
88
What are 2 types of surface waves?
Love Waves and Rayleigh Waves.
89
What are Love waves?
These are named after A. H. Love, a British Mathematician who discovered waves that move vertically.
90
What are Rayleigh Waves?
This is named after Lord Rayleigh who discovered surface waves in 1855.
91
What are some myths about earthquakes?
1. Earthquakes cause a big gap to open in the ground, and people get swallowed whole.
2. Mexico: Earthquakes occur because the god ripped the ground open so his minions and follows could cause mischief.
3. Peru: God came down because he wanted to count the people, and it was his footsteps that caused the earthquakes
4. Assam: People live under the crust of the Earth, and they bang on the "ceiling" to see whether anyone lives above.
5. Mozambique: The Earth is like a creature that experiences fever and chills. It's becuase Earth is sick that it's causing the earthquakes.
6. New Zealand: Mother Earth is carrying a baby in her womb, and the baby is kicking.
92
Where are the 2 main places earthquakes occur?
Along faults and plates.
93
Why are the boundaries btwn plate tectonics so prone to earthquakes?
When plate slide into each other, the surface is not flat or smooth, so they catch onto each other. Due to the excessive amount of force and pressure, it builds up until an earthquake can release that. The plates keep sliding until they get caught, and the cycle repeats.
94
Name 3 types of faults:
1. Strike-Slip Faults
2. Normal Faults
3. Reverse Faults or Thrust Faults
95
What are strike-slip faults?
Cracks that are formed when two plate are sliding past one another.
96
What are normal faults?
A plate is sliding downwards from another rock. These usually only occur when plates slowly shift apart and move away from each other.
97
What are reverse or strike-slip faults?
When one plate is exerting pressure on another plate, cracks in the rock appear and parts of the plate drop below other parts.
98
What are the names of the 2 scales that can measure earthquakes?
Richter Scale and Mercalli scale
99
How is the Richter scale measured?
It is calculated by the largest amplitude on the seismogram. It is a logarithmic scale.
100
How does the mercalli scale work?
Uses the observations from people who were there to guestimate the magnitude. This method is not as scientifical and the margin of error is very large because people could be in shock and over-exaggerate certain points.
101
How can you find the epicentre using primary and secondary waves?
The P and S waves travel at different speeds. We can find the time difference in the lag time between each. The closer the station is to the earthquake, the lower the distance (and vice versa).
102
Name 2 notable earthquakes in our history.
Any two of:
1. January 23, 1556: Shaanxi (China) Region had an Earthquake with a magnitude of 8. There were 830000 fatalies
2. July 27, 1976: Tangsha (China) had an earthquake with a magnitude of 7.8. There were 265000 fatalities
3. October 18, 1989: Loma Prieta (California) had an earthquake with a magnitude of 7.1. There were 63 fatalities. This earthquake was the first to be recorded on television for the warmup game 3 of the 1989 World Series (it ended up being delayed 10 days)
4. October 8, 2005: An earthquake with a magnitude of 7.6 killed 80261 people in Pakistan.
103
Name 2 notable tsunamis in the history of the Earth.
Any two of:
1. 1883 Krakatau Eruption between Sumatra and java caused series of tsunamis in 165 villages. It killed 36000 people. The Global Climates of this year dropped 3ºC, dubbing “Year Without Summer”
2. December 26, 2004: An earthquake with a magnitude of 9.1 on the coast of Sumatra produced tsunamis resulting in 225000 fatalities. It is the deadliest tsunami in history. Nearly 3.5 times as many people died compared to the one that happened in 1755, causing 60 000 deaths.
3. December 6, 1917: There were 200 fatalities in Nova Scotia
4. November 18, 1929: Tsunamis crashed into the coast of Newfoundland killing 29 people.
104
Name 2 notable volcanic eruptions in Earth's history.
1. 79 AD: Mount Vesuvius erupted, burying Pompeii, Italy. There were 3360 fatalities.
2. April 1815: The Tambora Volcano erupted in Indonesia. The massive volcano cloud blocked out the Sun, and global temperatures dropped 3ºC. 92000 people died due to starvation.
3. 1902: Mount Pelee in Martinique killed 30 000 people.
1985: Nevado del Ruiz (Columbia)’s high temperatures melted the snow and ice on top of the Andean Mountains (5390m). There were many mudflows which buried Armero, killing 25000 people.
4. June 15, 1991: Mount Pinatubo erupted sending ash flying out in a radius of 40km. The global temperatures were significantly cooler. There were 350 casualties.
105
The Earth has many layers - what are 2 ways we can classify them?
Chemical and physical.
106
How do we classify the layers chemically?
Crust, Mantle, Core
107
What is the role of the crust?
Outermost layer of the Earth. Anywhere from 35-70km in continents and 5-10 km in oceans. Elements in this region are much less dense, often rocks that have silicon or aluminum
108
What is the role of the mantle?
Composed of rocks that contain silicon, iron,a nd aluminum. It is 2900 km in thickness; divided into upper mantle and lower mantle. The movement of plate tectonics often originates from the mantle.
109
What is the role of the core?
There are 2 layers in the core: outer liquid core and inner solid core. The outer core is creatd by iron and nickel and is 1200 km thick. The inner core is entirely solid and contains almost all iron.
110
In terms of physical properties of the Earth, what are 5 ways of separating it?
1. Lithosphere
2. Atmosphere
3. Mesosphere
4. Outer Core
5. Inner Core
111
What is the role of the lithosphere?
Solid layer on the earth (includes the crust). It is separated into the plate tectonic boundaries.
112
What is the role of the atmosphere?
This is the plastic layer that the lithosphere floats on. It is partly solid but partly liquid.
113
What is the mesosphere?
This is mostly solid, very hot, and flows very slowly.
114
What is the outer core?
This is in an liquid state. There is much less pressure than the inner core; high temperatures keep the rock in molten states.
115
What is the inner core?
The Inner core is solid because of the high pressure from the rest of the Earth. Temperatures of the inner core can reach up to 9000ºC.
116
What is isostasy?
This is caused by the depressing or bending of the crust because of the mass on top (glacier, etc).
117
How does sound navigation and ranging help in the study of the Earth?
Scientists bounce sonar signals back and forth, so they can find the depth and the 'texture' of the 'ground.'
118
What is LITHOPROBE?
a scientific project (international) that is attempting to investigate evolution and nature of the lithosphere below Canada’s landmass and the oceans around
119
Ocean Drilling
A program that attempts to explore the structure and composition of ocean basins
120
What are 3 types of weathering?
Chemical weathering, mechanical weathering and biological weathering.
121
What is chemical weathering? What are the 3 main types of chemical weathering?
It measures the chemical change of the chemicals in the rock. It relies on heat and moisture.
Processes: dissolution, hydrolysis and oxidation.
122
What is dissolution?
It happens when rock breaks up into molecule sized particles and it dissolves into water. It is sped up by the presence of natural acids. This is the most common cause of cave formations.
123
What is hydrolosis?
It affects materials that contain silicates the most. The carbonic acid and the water react with the silicates, forming solid particles. The particles expand against the crystals due to their surroundings, slowly weakening the crystals.
124
What is oxidation and how does it help in chemical weathering?
When elements such as iron is exposed to oxygen for long periods of time, it starts to break down chemically into rust. Oxidized material is less sturdy unonxidized elements. It weakens it for mechanical weathering.
125
What is mechancal weathering? What are the 6 types of it?
This is when we break down materials into visibly smaller pieces without affecting the chemical composition.
* Exfoliation
* Thermal Contraction and Expansion
* Crystal Formation
* Abrasion
* Slaking
* Frost Wedging
126
What is exfoliation?
When rock layers start peeling off, the layers underneath have a lot less pressure on them. Layers of rock expand, crack, and peel.
127
What is thermal contraction and expansion?
Thermal cycling is due to the temperature change during the day and at night. During the day, it is much warmer and starts to expand and then cools down or contracts at night. It makes the rock relatively unstable.
128
What is crystal formation?
In intertidal areas, saltwater travels back and forth between rock and crystal. When it dries, the crystals dry and break off.
129
What is abrasion?
This is when there is physical contact between two things, ending up in the rock being scraped. We can see this evidence when glaciers travel along rocks, grinding and pulverizing it. We can also see this in fast-flowing water and large particles grinding the ocean floor.
130
What is slaking?
This is the constant cycle between wet and dry. If water happens to accumulate near crystals, the cohesiveness of the water can force the parts of the rock apart, promoting mechanical weathering.
131
What is frost wedging?
This is when water enters cracks in rocks, freezes, then expands. When it is warmer, there is an empty cavity. There is evidence of this everywhere on the road from the formation of potholes.
132
What is biological weathering?
This is what happens when the chemicals of something are changed. For instance, if there are plants that grow in between the rocks, and it expels organic acids whether it was meant for itself or it is dying, it would change the chemical formula of the rock in that section.
133
What is erosion?
Erosion is when loose particles move because of wind, water, or ice.
134
What are 3 ways that soil and particulates can be carried?
Suspension, Saltation, Traction
135
What is suspension in terms of erosion?
Relying on the Earth's elements to carry something without actually touching the earth's surface. It can occur in wind, water and ice.
136
What is saltation in terms of erosion?
This is when medium sized particles bounce around the earth's atmosphere. It kickstarts the movements of others as well. It can happen in wind and water.
137
What is traction in terms of erosion?
This is when large particles are moved. It can happen when sliding along earth's surface. This can happen in wind, water and ice.
138
What are 2 types of glaciers?
Alpine Glaciers (mountain ranges) and Continental Glaciers (ice sheets).
139
What are the 2 ways that glacier erosion can occur?
Basal Slip and Plastc Flow
140
What is basal slip?
In some glaciers, the pressure from the top can cause the bottom to start melting. It creates a bit of a slushy bottom, making the initial movement eaiser and faster.
141
What is plastic flow?
In colder regions, basal slip doesn't occur because it is not warm enough for it to melt. Instead, the ice crystals are constantly changing shape, eventually becoming relatively flat to offset gravity.
142
What is till?
The material is transported with the glacier and any deposition of glacial material.
143
What are the 3 important erosional processes for glaciers? What are their roles?
1. Plucking: When parts of glaciers fall off, ice at the bedrock starts to melt. The melted water surrounds the rock, and as the glacier passes, the rock remains.
2. Abrasion: When glaciers slide over rocks to smooth their surface.
3. Striation: When glaciers carrying rock scrape the bedrock, showing the direction of glacier movement.
144
What are the important terms of alpine glaciers?
1. Cirques: Horshoe shaped depressions formed by the erosion of glaciers.
2. Tarn: Ice melting forming small lake.
3. Horn: Several cirques erode causing sharp peak.
4. Arete: Two cirques eroding causing sharp ridge
5. Moraine: glacial rock appearing at the end of glaciers.
6. Lateral Moraine: moraines that form along glaciers.
145
What are the important terms of retreating glaciers?
1. Kettles: Chunks of ice that are left to form lakes.
2. Esker: When glaciers retreat, sand, gravel and boulders are left behind
3. Kames: Ponds and depressions caused by the glacial ice
4. Drumlins: egg shaped structures that are shaped in the direction of the flow. There is often deposition of till.
5. Terminal morraine: Deposits that have accumulated farthest in advance
146
What are the fluvial processes?
Solution Load: Dissolving small rock and minerals into the water
Hydraulic Action: Loosening of materials due to the movement of the water.
Abrasion: Large objects moving on the ocean floor
147
What is aggradation?
Sediment deposited in raised levels of the bed.
148
How can particles be transported by the wind?
Suspension: Small particles are transported through the air.
Saltation: Downwind movement bounce particles around
Creep: After salation, larger grains of sand are also moved around
