GEOL MIDTERM Flashcards
1
Q
What is the definition of Geology/geoscience?
A
The science that pursues an understanding of the earth and other planets.
2
Q
What are the 2 main areas of geology? Give a description of each.
A
- Physical Geology (Examines the materials that make up the planets and tries to understand the processes acting on these materials, as well as what’s formed as a result. It looks at what makes up the earth; what is happening on and beneath the ground.)
- Historical Geology (Examines earth’s history and understanding the origin of earth and its development through time; the history of life on earth. Deals more with the life on earth.) Ex) Looking at fossils.
3
Q
What are some problems that geology addresses?
A
Natural hazards, resources, world population and growth, and environmental issues.
4
Q
What are the 2 different ideas of how the earth is shaped? Give a description of each.
A
- Catastrophism: Says catastrophes are responsible for the earth’s creation. Believes in sudden processes. (Things like volcanoes shape the landscape)
- Uniformitarianism: Says Geological processes that operate today have also operated in the geologic past. It takes time, it’s not sudden: processes today have happened in the past.
5
Q
How old is the earth?
A
Around 4.6 billion years old.
5
Q
The present is key to the past: Natural processes have been uniform through time. True or false?
A
True.
5
Q
Are geologic changes slow or fast?
A
Very slow. Earth processes take a long time to create or destroy major landscape features.
6
Q
What is relative dating?
A
Dates are placed in their proper sequence/order without knowing the exact age in years.
7
Q
What do Geologists use with relative dating?
A
With geologic time scale to ‘time’ things, and apply Principles of Superstition and Fossil Succesion.
8
Q
What is the Geologic Time Scale?
A
It’s Earth’s calendar; it summarizes Earth’s history. It exists because the Earth involves vast amounts of time, and humans are only a tiny part of it.
9
Q
What are the different stages of the Geologic Time Scale?
A
Each eon is divided into an era, nad each era is divided into periods, and each period is divided into epochs.
1. Eons (The largest subdivision of time: Hundreds of thousands of Ma)
2. Eras (65 to hundreds of Ma)
3. Periods (2 to 70 Ma)
4. Epochs (0.011 to 22 Ma)
10
Q
Why oes the Precambrian section take up 88% of the time scale?
A
Because it’s harder to specifically ‘time’ those fossils, if any were found.
11
Q
How much of earth’s history do humans occupy?
A
0.000001%
12
Q
What are the 4 different eons?
A
- Phanerozoic: Visible life, from 542 to 0 Ma.
- Proterozoic: Before life, from 2.5 to 0.452 Ga.
- Archean: Ancient, from 3.8 to 2.5 Ga.
- Hadean: Hell, from 4.6 to 3.8 Ga.
12
Q
What are the 3 different eras?
A
- Cenozoic: Recent life. The Era we’re in.
- Mesozoic: Middle life.
- Paleozoic: Ancient life.
12
Q
What does Ga mean?
A
Giga annum: Billions of years.
12
Q
What does Ma mean?
A
Mega annum: Millions of years.
13
Q
What does Ka mean?
A
Kilo annum: Thousands of years.
14
Q
What 3 major eons is the Precambrian stage divided into?
A
Hadean, Archean, and Proterozoic.
15
Q
What 3 major eras is the Phanerozoic eon divided into?
A
Paleozoic, Mesozoic, and Cenozoic.
16
Q
What is the goal of science?
A
To discover patterns in nature and use this knowledge to make predictions or generate an understanding of phenomena.
17
Q
Why do we look for patterns in science?
A
Because we assume that nature is consistent and predictable.
18
Q
What is a hypothesis?
A
An untested explanation.
19
Q
What is a theory?
A
A well-tested and widely accepted view that scientists agree best explains certain observable facts.
20
How are geological questions investigated?
With deductive reasoning and scientific methodology. Any question or idea in geology must be tested.
21
What is the scientific method? What are its stages?
It uses observations and experiments to build and refine hypotheses that explain phenomena. Any explanation for a process/phenomenon must be testible.
22
What are the 4 stages of the scientific method?
1. Observation (Use inductive reasoning)
2. Build/modify your hypothesis/model.
3. Make a prediction (the result you're expecting).
4. Design an accurate test, and then test your prediction.
23
What does it mean to 'pass the test' in stage 4 of the scientific method? What does it mean to fail?
To pass means that you got the expected results, and it can become a theory when repeatedly tested.
To fail means you got unexpected results, so you can modify (go back to step 2) or reject your hypothesis.
24
The theory of plate tectonics is the worst explanation for how the earth 'works'. True or false?
False, it's the best explanation.
25
How many rigid plates are on earth?
At least 15.
26
How does plate motion define the 3 types of plate boundaries (It provides a unified mechanism that explains what)?
1. The distribution of earthquakes and volcanoes.
2. Changes in past positions of continents and ocean basins.
3. The origins of mountain belts and seamount chains.
4. The origins and ages of ocean basins.
27
What are plate boundaries? How were they identified?
Places on earth where tectonic plates meet.
They were identified by concentrations of earthquakes.
28
What phenomena are associated with plate tectonics?
Things like Volcanoes and Earthquakes; they become more and more common the closer you get to the plate boundaries. Plate interiors are almost earthquake-free.
29
What was Alfred Wegener's Continental Drift Hypothesis?
Pangea; a former supercontent that split into the continents we have now from continental drifts.
30
What were the Continental Drift Hypothesis' 3 major evidence points?
1. The fit of the continents (if you squish them together, they fit like a jigsaw puzzle)
2. Distribution of fossils (fossils from specific animals were found in both Africa and South America where, if his hypothesis was correct, the 2 continents would've touched.
3. Matching geologic units (Mountain ages and rock types are the exact same in North America, Greenland, Europe, and Africa.
It was not widely accepted because he had no credible hypothesis for 'how' the continents had moved.
31
Why was the continental drift hypothesis not widely accepted? Who later provided a framework for how they moved?
It was not widely accepted because he had no credible hypothesis for 'how' the continents had moved.
Henry Hess's theory of Seafloor Spreading later provided an explanation.
32
What 2 things is the universe made up of? What are their definitions?
1. Matter (A substance of the universe that takes up space and is made of mass, density, and weight.)
2. Energy (The ability to do work that's made of heat, light, and the pull of gravity.
33
What is the Hot Big Bang Theory?
A theory of the formation of the universe: It exploded in 13.8 Ga and has been expanding ever since. When the big bang happened, all the mass and energy was extremely dense and the temperature was more than 10 to the power of 32 kalvin. Galaxies didn't form until 1-2 billion years after the big bang.
34
What is inflation?
The rapid expansion of the universe.
35
What is Nebula? Over time, what happens to it?
A rotating cloud of gas and dust.
Over time, it contracts and clumps. It condenses and becomes more dense; it starts collapsing because of gravity. These contractions and rotations will form a disk.
36
What is gas made up of?
Hydrogen and helium.
37
What is dust made up of?
Iron, magnesium, and silicon.
38
What is one light year?
The distance light travels in a year (9.46 trillion km)
39
What is a proto-sun/star?
A flat, rapidly rotating disk will form with the matter concentrated at the centre, and the matter in the middle is the proto-sum/star. When it collapses, the movement will increase the density, temperature, and rotation, and the energy can convert to heat or light.
40
What is the mass-to-energy conversion?
The sun 'burns' helium
657 tons of H/meter = 653 tons of He/minute
41
What is the protoplanetary disk?
The disk of remaining gas and dust where planets will eventually form.
42
What are planetesimals? How do they form?
They're accretion of small clumps of dust.
Away from the Proto-sum, dust starts with coalesce and forms planetesimals, which clump into a lumpy protoplanet.
43
When did planets form?
Around 4.56 Ga
44
What does Homogeneous mean?
That it's uniform all the way throughout; it has no layers.
45
What is the earth believed to be very similar to? What is it made with?
Chondrite meteorites.
They're made with minerals like O, Si, Mg, Fe, and metals.
46
What are the 5 parts of early earth formation?
1. During the middle-to-late stages of earth's accretion, a Mars-sized body hit the earth.
2. The giant impact propelled a shower of debris from both the impacting body and the earth into space. (125 parts were dispelled into space).
3. The impact sped up the earth's rotation, and tilted the 'true north' by 23 degrees.
4. The earth re-formed as a molten body.
5. The debris from the collision clumped together and formed the moon.
47
What has a very similar composition to the earth's mantle?
Moon rock.
48
What are 3 sources of heat in the earth's interior?
1. Accretion. (From the objects that accreted to form earth)
2. Compression (Compressing a planet under its own weight causes heat. The earth grew and increased in density and compression, causing the materials to heat)
3. Radioactive Decay (Disintegration of radioactive elements. Elements decay to produce new elements, and some of this mass will turn into energy, which is heat)
49
What allows the earth to differentiate on the basis of density?
The earth partially melted.
50
What is the density segregation of liquids?
Iron and nickel blobs (the denser blobs) coalesce and migrate to the centre of the earth, and lighter silica-rich materials float towards the outer layers of the earth.
51
How many layers of the earth are there and what are they? What are their densities?
There're 4.
1. The solid iron inner core
2. The liquid iron inner core.
(The above 2 are made of very dense iron in the centre of the earth)
3. The mantle
(Has very intermediate density)
4. The crust
(Has very low density)
52
Low density sinks to the core and high density floats to the surface. True or false?
False. Low density floats and high density sinks.
53
How did oceans form?
When the earth got cool enough, moisture condensed and accumulated to form oceans.
54
Photosynthetic Algae formed free oxygen around 3.8 Ga. True or false?
True.
55
What are the 3 goals of maps?
1. To locate places
2. To see patterns by looking at the distribution of geological features across a space/area
3. To compare and contrast information
56
What is a topographic map?
A 2D representation of a 3D landscape.
57
What does DEM stand for? What maps are they used on?
Digital Elevation Model. It has contour lines and looks like it'd feel bumpy.
It's used on a topographic map.
58
What features does a topographic map have?
1. Topography/relief. Shown by means of contour lines that show mountains, valleys, slopes, and depressions.
2. Hydrography/water features. Shows lakes, rivers, streams, swamps, rapids, and falls.
3. Culture. Shows buildings, urban development, roads, trails, railways, and bridges.
4. Land boundaries. Shows international, provincial/territorial, and geographical boundaries.
5. Toponymy. Shows places, water features, landforms, and boundary names.
59
What is a benchmark (BM)?
How high a point is in real life.
60
What 3 things can you find on a map?
1. A title
2. A legend (Tells you what each symbol means)
3. A map scale (Size of map distance compared to the real-life distance)
61
Where are contour lines drawn?
Where a horizontal plane intersects the land surface.
62
What's a contour interval?
The difference in elevation between any 2 adjacent contour lines.
63
What's the datum?
The reference level. It's usually sea level: All contour lines represent elevations above sea level.
64
What's interpolation used for?
To estimate the elevation of a point located between 2 points of known elevation.
65
What's extrapolation used for?
To estimate a point that's located in line beyond points of known elevation.
66
Will contour lines ever cross each other?
No, except when an overhanging cliff is present.
67
When can contour lines merge to form a single contour line?
Where there's a vertical cliff or wall.
68
What are index contours?
They generally have the elevations printed on them; it's every 5th line, and it's usually bolded.
69
What represents a uniform slope?
Evenly spaced contour lines of different elevations.
70
What makes depression contours stand out?
They have hachure marks on the downhill side, representing a closed depression.
71
How do you use contour lines to indicate streams?
You use a V pattern. The inside of the V always points upstream.
72
What is the gradient? How do you find it?
The measure of the steepness of a slope.
It's expressed in m/km
Lines that're spread further apart represent a gentle slope; closer together means it's steep.
To find the gradient of a surface on a map, you divide the relief by the distance measured between 2 points.
73
What's relief?
The difference in elevation between 2 points.
74
What are the 3 types of map scales?
1. Fractional scale (Ratio)
2. Bar/Graphic Scale
3. Verbal Scale
75
What's a small-scale map vs a large-scale map?
Small-scale covers a global region. It shows little detail because it covers so much area.
Large-scale: A local scale; it shows more detail because it covers less area.
76
What are cross-sections?
A diagram that shows changes in elevations of the land surface along any given line. Used to observe geological features in 3D.
(When you put a paper on a topographic map and mark all the elevations)
77
What is vertical exaggeration? What is the formula for finding it?
Exaggeration of the vertical dimension of the profile than how it appears in nature compared to the map dimension.
Some lines are exaggerated in order to help you better see the landscape on a map.
Horizontal scale/Vertical scale = VE
78
What 2 coordinate systems are commonly used?
Geographic coordinates (latitude/longitude)
UTM (Universal transverse Mercator)
79
What's a great circle? What's the word that describes 1/2 of a great circle?
Results when any plane passes through the centre of the globe and the North and South Poles.
Meridians: they run in the North-south direction from one pole to another (Longitude)
80
What does the equator do?
Divides the earth into its north and south hemispheres.
81
What are parallels or latitudes?
Imaginary lines that're parallel to the equator.
82
How many zones does the UTM divide the earth into? Where does zone one start?
60 zones.
Anything west of the Prime Meridian is called west longitude, and anything east is east longitude.
Zone one starts at 180 degrees west.
83
Where are easting and northing measured from on the UTM?
Easting is measured from the edge of the zone you're looking at, and nothing is measured from the equator.
84
What are the 4 different projections of the earth onto a map that we can have?
Equal-area proportions, which keeps the areas of continents in their correct proportions.
Conformal Map projection: The outline of the continents and oceans mapped over a large area are distorted.
Azimuthal maps: Can be equal-area or conformal, but are constructed around a specific point.
Mercator Projection: Wrapping a piece of paper around a map and outlining the areas. Distorts because it can't keep the shape of the earth.
85
What is planetary differentiation?
Segregation of different layers.
86
How do we know the earth is layered?
Because of the density; denser parts (Iron and nickel blobs) sink to the core of the earth, and less dense parts (lighter silica-rich materials) float away from the centre, creating layers in the earth's interior.
87
What does coalesce mean?
Coming together to form one mass.
88
What material is under the continents and the ocean?
Under the continents is granite, and under the ocean is basalt. These 2 make up the earth's crust.
89
What does the core look like it's made of? What does the mantle look like it's made up of, and how does it come up to the earth's surface?
The core looks like iron meteroite, and the mantle looks like perodite, which volcanoes can bring to the surface.
90
Seismic wave velocities change with density. True or false?
True.
91
What happens when earthquake waves hit the fault plane?
The fault plane splits the rock and creates an earthquake.
92
What are 2 things that change the deeper you go into the earth?
Pressure (The weight of the rocks above increases with depth)
Temperature (Heat is made in the earth's interior)
93
What is Geothermal Gradient?
The amount that the earth's temperature increases with depth.
It varies around the globe because the thickness of the crust varies depending on whether it's a continent or ocean that you're looking at.
More pressure means an increase in heat.
94
What are the different temperatures of the earth's layers?
The centre may reach 4700 degrees
The crust is around 20-30 degrees, plus 10 degrees at greater depths.
95
Where is the earth's crust thickest/thinnest?
Thickest under mountain ranges (70 km), and thinnest under mid-ocean ridges (7 km).
96
What is the average thickness of the continental crust? What's it made out of?
The average thickness is 35-40 km.
It's felsic (granite)
97
What is the average thickness of the oceanic crust? What's it made out of?
Average thickness is 7-10 km, denser than continental crust.
It's mafic (basalt and gabbro)
98
What's the moho discontinuity?
The base; the seismic velocity change between the crust and upper mantle. It's the line separating the crust an mantle, because there's an abrupt change of seismic velocity.
99
What is the crust made of?
98.5% of it is made of 8 elements: Oxygen is the largest of them
Most minerals seen in the crust are made of silicate (silicone and oxygen)
100
What is the largest layer of the earth? What's it made of?
The mantle.
It's made mostly of solid rock, consists entirely of peridotite (an ultramafic rock), and takes up 82% of the earth's volume and is 2885 km thick.
101
What are the 3 layers of the mantle?
1. Upper Mantle: This is just below the crust and is 660 km deep.
2. Lower Mantle: From 660 km to 2900 km.
3. Transition Zone: From 410 to 660 km.
102
What mixes the mantle?
Mantle convection: Convection below around 100km. The mantle rock softens and flows like silly putty.
103
What is the core and how big is it? What are the 2 parts of it, and what are they made of?
It's an iron-rich sphere with a radius of 3471 km.
1. Outer Core: Made of liquid. It's so hot that the liquid flows. It's 2,255 km thick.
2. Inner Core: Made of solid iron-nickel alloy. It's solid because of the pressure and has a radius of 1,220 km.
104
What is the lithosphere? How deep does it go? What's it made up of?
The outermost 100-150 km of earth. It's rigid and doesn't flow. It's what makes up tectonic plates.
It's made of the crust and upper mantle.
105
What is the asthenosphere? How deep does it go? Where is it shallow/deep?
The mantle below the lithosphere, and goes down around 700 km.
It's shallow under the oceanic and deeper under the continental lithosphere.
106
What are 2 ways we can classify the earth's layers?
1. By chemical composition (The core, mantle, and crust)
2. By physical properties (Inner/outer core, mesosphere, asthenosphere, lithosphere, and ocean).
107
What are the 2 theories of mantle convection?
1. Whole mantle convection. Says the earth is heated by the whole core (it rotates through the whole inner core).
2. Stratified convection. The boundary near 700 km separates the 2 convection systems (the lower mantle connects more sluggishly than the upper mantle)
108
What are the 2 types of lithosphere? What are their characteristics?
1. Continental. Around 150 m thick, made of felsic to intermediate crustal rocks that're around 25-70 km thick. It's light, less dense, and more buoyant, so it floats higher because the crust is made of lighter silica materials.
2. Oceanic. Around 100 km thick, made of mafic crust (basalt and gabbro) that're around 7-10 km thick. It's heavier and more dense and less buoyant, so it sinks lower.
109
What do I mean when I say that the continental crust floats higher?
That it rises above sea level instead of sinking.
110
The asthenosphere bends elastically when loaded. True or false?
False. The lithosphere does.
The asthenosphere flows plastically when loaded. (It flows out of the way when the lithosphere bends)
111
What is gravitational equilibrium?
The gravitational force that pulls the lithosphere down is counterbalanced by the buoyance force that pushes it up.
112
What is subsidence?
The gradual sinking of an area of land. It's very slow; like 1 km/year.
113
What is isostasy?
The concept of subsidence and rebound due to ice loading and deglaciation.
114
What is the geographic pole?
The line on which the earth spins.
115
How does the Magnetic Field resemble the field produced by a giant dipole bar magnet?
Because the field has North and South ends, it grows weaker with distance, and the magnetic force is directional.
116
The North pole of the bar is near the earth's geographic South pole. True or false?
True. The North compass arrow points to the bar magnet south pole.
117
What is a magnetosphere? What distorts it?
When magnetic field lines form a shield around the earth. They're important for sustaining life; without them, the earth would be too hot.
Solar wind distorts it.
118
Do magnetic poles intersect the earth's surface? What are their characteristics?
Yes.
They're located near geographic poles and move constantly.
119
Geographic and magnetic poles are parallel. True or false?
False. They are not parallel.
120
What is declination?
The difference between the geographic and magnetic North.
121
What is inclination?
The angle between the magnetic field line and the surface of the earth.
It depends on the latitude.
122
The polarity of the magnetic field doesn't stay constant; sometimes it flips. True or false?
True. We don't know why it flips.
123
Where is the reversed North magnetic pole?
Near the south geographic pole
124
What are chrons and subchrons when looking at the magnetic reversal time scale?
Chrons: Longer intervals (500 to 700 or more Ka)
Subchrons: Shorter intervals (around 200 Ka)
125
What are industrial minerals?
Raw materials for manufacturing.
126
What are ore minerals?
Sources of valuable metals
127
What are gem minerals?
They attract human passions.
128
What do minerals mean to mining companies and nutritionists?
Miners: Anything taken out of the ground
Nutritionists: Anything with a nutritional element.
129
What do minerals mean in geoscience?
A naturally occurring, formed geologically, solid, crystalline structure with a definite, but not necessarily fixed, chemical composition, inorganic.
130
What does naturally occurring mean?
It's formed by natural processes without the benefit of human action or intervention.
131
What does it mean for a mineral to be formed geologically?
It's formed by a geologic process, like freezing from a melt, precipitation from a dissolved state in water, and chemical reactions at high pressures and temperatures.
132
What are biominerals?
Minerals are produced by living organisms. Also known as biogenic minerals.
133
What does it mean for a mineral to be solid?
It's a state of matter that can maintain its shape indefinitely.
134
What's a crystalline structure?
Atoms in a mineral are arranged in a specific order. This atomic pattern is called a crystal lattice.
135
What is an amorphous/mineraloid mineral? An example?
A solid with disordered atoms.
EX) Glass. It doesn't have a crystalline structure, so it's not a mineral.
136
What is a definite chemical composition in a mineral?
Minerals that can be defined by a chemical formula. Every mineral must have a chemical formula. However, they're not always necessarily fixed; the ratio of elements must always be the same, but some elements can substitute for each other because they have similar properties.
137
What does it mean when a mineral is organic? Are minerals supposed to be organic?
Most minerals have carbon-hydrogen bonds, and other elements may be present (they're common products of living organisms).
No, minerals are supposed to be inorganic.
138
What 3 things are required for minerals to grow?
1. The elements needed to make mineral crystals must be present in sufficient abundance and appropriate proportions. (Elements must be present, with the right amount of them.)
2. Physical and chemical conditions must be favourable.
3. There must be sufficient time for the atoms to become arranged into a lattice.
139
What is a crystal?
A continuous, single piece of crystalline solid. It's compounds of atoms bonded together
Crystal faces grow naturally as the mineral forms. The angles and faces reflect the crystalline structure.
If it's more than one piece, it's considered a mineral.
140
What is the crystal lattice?
The atomic arrangement.
141
What defines the crystal structure?
The way the atoms are packed.
142
What 3 things do the physical properties of minerals depend on?
1. The identity of the atoms
2. The arrangement of atoms
3. The nature of the atomic bonds.
143
What are minerals?
Compounds of atoms that're bonded together.
144
What are atoms? What 2 parts are they made of?
The smallest particles of matter that can't be chemically split.
They're made of the nucleus and electron clouds.
145
What's an element?
A group of the same kinds of atoms.
146
What are the charges of protons, neutrons, and electrons?
Protons: Charge of plus one and a mass of plus one.
Neutrons: Charge of zero and a mass of plus one.
Electrons: Charge of -1 and no mass.
