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Geo 102 > mid term 3 > Flashcards

mid term 3 Flashcards

1
Q

Acid volcanos

A
  • Zones of the ocean and continental crust (subduction)
  • creates andesite, Rhyolite rock
    2 kinds:
  • Lava domes formed only of lava layers, round shape
  • Stratovolcano’s formed from lava and ash cone shape
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2
Q

Basaltic volcanoes

A
  • Widespread low layers of lava
  • Spreads over a wide distance
  • Looks like a hill side very flat
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3
Q

Caldera

A

Volcano that has collapsed
* Empty magma chamber causing
ground to sink
* Cauldron-like depression

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4
Q

Hazards

A
  • Pyroclastic flow
  • Lahars
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5
Q

Lahars

A
  • Mudflow or debris flow
  • Composed of pyroclastic material, rock
    debris and water
  • Caused from mixing with snow, lake
    water, wet soil
  • Density of wet concrete
  • Highly destructive
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6
Q

Pyroclastic flow

A
  • Collapse of part of a lava dome while it’s still active
  • Fast-moving current of hot gas and volcanic material
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7
Q

Jökulhlaups

A
  • Glacier outburst flood
  • Some are caused by subglacial volcanic eruption
  • Lava melts large quantities of water
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8
Q

Seismic waves

A
  • The movement of the two pieces of crust (cm to meters)
    releases seismic energy into the surrounding crust.
  • The shockwaves radiate outward from the focus and epicenter.
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9
Q

Seismographs

A

Detects and records the motion of the ground
* P-waves (body waves) arrive first, followed by S-waves
* A network of seismographs or
seismometers can allow you to pinpoint the quake’s origin

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10
Q

Foreshock

A
  • A foreshock can happen before the
    main shock.
  • Can be minutes, days or even
    years!
  • Occurs for about 40% of
    moderate to large earthquakes
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11
Q

Aftershock

A
  • An aftershock or a series of
    aftershocks may occur after
    the main shock.
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12
Q

Focus

A
  • A focus (or hypocenter) of
    an earthquake is the
    subsurface area along a fault
    plane, where the motion of
    seismic waves are initiated
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13
Q

epicenter

A
  • An epicenter is the area at
    the surface directly above
    the focus
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14
Q

Richter scale

A
  • Based on amplitude of seismic waves, which is related to
    energy released.
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15
Q

Moment magnitude scale

A
  • the scale measures earthquake energy by fault movement, rupture size and rock strength
  • Calculated from:
  • a) the distance a fault is moved
  • b) the amount of force required to move it.
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16
Q

Damage potential

A

based on
- the location of focus and epicenter
- duration and amount of shaking
-soil and rock type in the area
- near slopes that can have land or mudlsides
- tsunami is near the ocean
- population concentration

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17
Q

Liquifaction

A
  • Water saturated, unconsolidated
    sediments become liquid
  • Caused by shaking from seismic
    waves
  • Can cause significant damage with
    collapse of infrastructure
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18
Q

Damage

A
  • Fires
  • Landslides
  • Building collapse
  • Infrastructure
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19
Q

What is a glacier

A
  • A moving mass of ice,
    flowing downhill like a slow
    river
  • Ice moves downhill due to
    gravity
  • Two major ice sheets:
    Greenland and Antarctic
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20
Q

How to make a glacier

A
  • Cold enough for snow to last
    year round
  • Over time the snow
    accumulates and increases in
    density (snow gets
    increasingly squished the
    more it is buried by newer
    snow)
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21
Q

PROCESSES OF SNOW
METAMORPHISM

A
  • Molecules transfer
    between snow grains,
    reducing the surface area
  • Thermodynamically unstable
    (until a sphere shape)
  • Compaction causing
    density increase
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22
Q

Firn to ice transition

A

Snow → Soft and fluffy (low density, loose crystals).
Firn → Firm and airy (compacted but air can still move).
Ice → Solid and sealed (high density, air trapped as bubbles).

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23
Q

Ablation
(removing mass)

A
  • MELTING
  • Affected by air temperature
  • Albedo: very reflective surfaces reflect more sun (depends how
    dark the ice surface is. Fresh
    snow is the most reflective)
  • Ice can’t be above 0oC…just
    melts more
  • Latent heat warms snow and ice
  • CALVING
  • Where blocks of ice break off the front of glaciers that flow into the sea or into lakes
  • Creates icebergs
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24
Q

Glacier Mass balance

A
  • Mass balance: change in mass of an ice body or glacier over a period of time
  • Positive mass balance: cold periods with lots of snow.
    Snow build up > glacier melt. Glacier builds up and
    advances down the valley.
  • Negative mass balance: warm periods with lots of melt. Melt > snow build up. Glacier thins and retreats up the valley.
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25
Q

Glacier mass balance

A
  • Accumulation at higher
    elevations
  • More snow
  • Colder temperatures
  • Less melt
  • Ablation at lower
    elevations
  • Warm enough to melt
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26
Q

Types of Glaciers:

A
  • cirque
    -Valley (Alpine) glacier
    -Tidewater
    glaciers
  • ice cap
  • ice sheets (Greenland)
  • Ice sheets
    (Antarctic)
  • Ice shelves
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27
Q

cirque

A
  • Bowl-shaped feature
  • This is where glaciers
    begin to form
  • Very high up in the
    mountains
  • Tend to be North
    facing in the N.hemisphere
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28
Q

Valley (Alpine) glacier

A
  • Flows through the
    mountains (controlled by
    topography)
  • Erodes and removes
    material changing a v-
    shaped (river) valley into a
    u-shaped
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29
Q

Tidewater
glaciers

A
  • Glaciers that flow into the
    ocean
  • As they move into the deep
    water, the ice starts to
    float
  • These glaciers ‘calve’ and
    produce icebergs that float
    out to sea
  • Sensitive to warming ocean
    waters (cause melt and
    the retreat of these glaciers)
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30
Q

ice cap

A
  • When there is enough ice
    to cover topography (i.e
    ‘capping’ the underlying
    rock)
  • Forms a dome shape
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31
Q

ice sheets (Greenland)

A
  • 81% of Greenland is
    covered in ice
  • The ice sheet is up to 3
    km thick!
  • Lots of lakes form on the
    surface of the ice in the
    summer
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32
Q

Ice sheets
(Antarctic)

A
  • The Antarctic is the coldest and the
    driest place in the world
  • Largest ice sheet in the world (60 m
    of sea level rise if it all melts)
  • Has the oldest ice in the world (up to
    1 million years giving us a record of
    past climate)
  • Divided into the West Antarctic Ice
    Sheet (WAIS) and the East Antarctic
    Ice Sheet (EAIS)
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33
Q

Ice shelves

A
  • When glaciers or ice streams
    flow into the ocean but don’t
    break off they become ice
    shelves
  • Floating on the ocean so
    melt more when the ocean
    waters warm up
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34
Q

Supraglacial:
rivers

A

Moulin = Nature’s water slide

Surface water enters the glacier through moulins, like a slide leading water straight to the glacier bed.
Summer = Water on the go

Warmer temperatures mean more melting, so there’s lots of water moving during the day in summer.
Winter = Almost no show

Usually no meltwater in winter, but occasionally there’s some depending on the conditions.
Antarctica = Too cold to flow

No surface water here because it’s simply too cold for melting to happen.

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35
Q

hwo do glaciers move

A
  • when ice is under pressure it has lots of ice lying on top of it it becomes soft
  • this is called ice creep
  • In the top 30m of
    the glacier, the ice is
    brittle (as it’s not
    under enough
    pressure to flow)
    and so it cracks.
  • the cracks are called crevasses
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36
Q

Supraglacial:
Lakes

A
  • Can either overflow into a river (like a normal lake).
    Or crack through km’s of ice to the bed.
  • Millions of m3 of water is added to the bed of the ice in a matter of hours
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37
Q

Subglacial
(water at the base of the ice)

A
  • Water can flow by spreading
    out at the bottom of the ice
    either over the rock or into
    sediments
  • Lots of lubrication for the ice
  • Causes fast flow
  • Sometimes the water melts
    out large channels into the
    base of the ice that removes
    the rest of the water quickly
  • Less lubrication for the ice
  • Causes ice flow to slow down
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38
Q

Glacial erosion

A
  • When ice moves across a
    surface, material is eroded by:
  • Abrasion
  • Plucking
  • Also glacio-fluvial action (i.e.
    water)
  • Erosion is helped by weakness in the rock, such as cracks or
    joints.
39
Q

Abrasion caused by Glacial movement

A
  • Rocks frozen in the ice drag
    along the bedrock
  • Create scratches in the rock
    called striations
40
Q

Glacial plucking

A
  • Subglacial rocks are broken up by freeze-
    thaw action.
  • Ice freezes onto rock at the base and pulls
    it away as it flows downhill.
  • The rocks frozen in the ice later act as
    abrasion and erosion agent
41
Q

U-shaped Valley

A
  • Glaciers produce valleys with “U”
    shaped cross-section, steep walls
    and generally broad & flat floor
  • Steepened, deepened and widened
42
Q

Fjords

A
  • U-shaped valleys filled with sea water
  • Due to sea level rise as the large ice sheets melted after the last
    glacial period
43
Q

Hanging valley

A
  • A former tributary above a U-shaped
    glacier valley
  • Higher than the floor of the main valley
  • Main glacier cuts off end of valley = truncated spur
    Milford Sound, New Zealand
    Truncated spur
44
Q

Erratics

A
  • Rocks of varying shapes & sizes
  • often fall on the surface of the
    glacier from the mountains that it
    flows through
  • Moved a long distance by glacier
    (or iceberg )
  • Often identifiable from their
    different composition compared to
    where they are deposited
45
Q

Glacial sediments

A

All ice-related deposits are called
glacial drift. Two main types:
- Till (primary deposition)
- Stratified drift (secondary
deposition)

46
Q
  1. Till (primary deposition)
A
  • Sediment deposited directly by glacier
    ice without disturbance
    – Texture: Unsorted, very angular,
    mixture of fine and coarse material
    – Structure: Unstratified (all mixed up)
47
Q
  1. Stratified drift (secondary
    deposition)
A

Formed by: Water from melting glaciers (glacial meltwater).
Texture: Well sorted mix of clay, silt, sand, gravel, and boulders.
Structure: Layered (stratified) from water flow, with parallel layers.

48
Q

Moraines

A

Ground moraine = Bottom blanket
End moraine = Glacier’s stop sign
Lateralmoraine = Side stripes
Medial moraine = Middle merge stripe.

49
Q

Terminal moraine

A
  • The glacier acts as a bulldozer
  • Location of the moraine shows maximum
    extent of the glacier
  • May have ridge form
  • And, terminal moraines often impound
    proglacial lake
50
Q

Lateral moraines

A
  • Till ridges along valley
    sides
  • Mostly angular & unsorted
    material
  • Mark previous “width” of
    the glacier
51
Q

Eskers

A
  • Sinuous, meandering ridge made of course sand
    and gravel.
  • Deposited from englacial/subglacial rivers
  • Show the direction of glacial water flow
52
Q

kettle lakes

A

Formed by: Melting ice blocks buried under sediment.
Process: As the ice melts, the depression gets bigger.
Characteristics: Round, deep, and often found in clusters.
Common in: Southern Ontario.

53
Q

Drumlines

A
  • Elongated ridges of till
  • Formed under the ice and shaped by ice flow
  • Parallel with flow
  • Steep end (oval or rounded) faces where ice
    came from
  • Lee side (downflow side) tapers
54
Q

Geomorphology

A
  • Geomorphology (morph means shape or form) is the
    science of landforms including origin, evolution, form, and spatial distribution of landforms.
55
Q

Denudation

A
  • Process that wears
    away or rearranges
    landforms
  • Weathering
  • Mass movement
  • Erosion
  • Transportation
  • Deposition
56
Q

Slope stability

A

For material to move: Gravity needs to overcome friction, resistance to movement, and how the particles stick together.
Movement happens if:
The slope is steep enough for gravity to push the material.
Rain or wind can loosen the material.

57
Q

Weathering

A
  • Weathering = process
    that breaks down rocks
    1. Physical weathering
    (mechanical
    weathering)
    2. Chemical weathering
    (dissolves rock)
58
Q

Regolith

A
  • Regolith: Broken up material and rock on the surface of bedrock
    due to weathering
  • Bedrock: Consolidated, solid rock = PARENT ROCK
59
Q

Parent Material

A

The material soils form from, like loose sediments or weathered rock

60
Q

Physical weathering: Frost weathering

A
  • Freeze-thaw action
  • Water expands when it freezes (by 9%), and fractures rock
  • Dominant process in arctic and high-mountain environments
61
Q

Physical weathering: Salt weathering

A
  • Water evaporates from sandstone pores, leaving salt
    crystals behind.
  • Crystals grow and disintegrate rock grains.
  • Occurs in arid and semiarid regions, and coastal regions.
62
Q

Physical weathering: Pressure-release

A
  • Exfoliation: rocks peels or slips off in sheets (also called sheeting)
  • Rock is exposed at the surface, releasing pressure, so rock expands slightly
63
Q

Chemical weathering

A
  • Chemical breakdown of minerals in rock through exposure to
    precipitation and water
  • Most effective in warm, moist climates
64
Q

Chemical weathering: acid rain

A
  • Water vapour can dissolve carbon
    dioxide producing carbonic acid
  • Rain acidity has been increasing
    in Europe since the industrial
    revolution
65
Q

Chemical weathering: spheroidal
weathering

A
  • Edges of rocks become rounded
  • Water penetrates the rock joints and
    dissolves weaker minerals
  • Rocks can shed shells like an onion
66
Q

Chemical weathering: oxidation

A
  • ‘rusting’ – iron oxide
  • Iron is removed from the minerals in the rock
  • Rock is then more susceptible to disintegration
67
Q

Chemical weathering: carbonate
dissolution

A

Rain contains carbonic acid that dissolves limestone, a process called carbonation. This shapes landscapes with limestone, creating karst topography

68
Q

Karst: sinkhole

A
  • Circular depressions in
    the ground
  • Either from collapse
    into underground
    cavern
  • Or slow subsidence of
    surface material
    because of dissolving
    of limestone
69
Q

Karst: caves and caverns

A

Formed by: Water dissolving limestone.
Location: Just below the water table.
Speleothems: Calcium carbonate redeposits in the caves, forming structures like stalactites and stalagmites.

70
Q

Karst: speleothems

A
  • Stalactites grow down
    from the ceiling
  • Stalagmites grow up
    from the floor
  • They can join to form a
    column
71
Q

Mass Wasting Processes

A
  • Steepness of slope determines when loose material comes to rest, depending on size and
    texture of grains
  • Driving force: gravity – steepness of slope
  • Resisting Force: shear strength of material, cohesiveness and internal friction working against
    mass movement
  • Angle of repose: balance of driving and resisting forces
72
Q

Causes of mass wasting

A
  • Weathering (e.g. freeze-
    thaw action weakens rock
    joints)
  • Saturation of slope (e.g.
    heavy rain)
  • Oversteepening from
    erosion (river or ocean
    erodes base)
  • Earthquake shakes debris
    loose or fractures rock
73
Q

Classes of mass movement

A
  • Material can:
    1. Fall
    2. Slide
    3. Flow
    4. Creep
74
Q

types of mass wasting

A

Dryer & Slower:

Soil Creep: Gradual downhill soil movement.
Moderate Speed:

Translational Slide: Moves along a flat surface.

Rotational Slide (Slump): Moves on a curved surface, often due to water on clay layers.
Faster & Wetter:

Earthflow: Slow to moderate flow of saturated soil.
Debris Avalanche: Rapid movement of loose debris.

Mudflow: Fast-moving flow of water and fine sediments.
Fastest & Steepest:

Rockfall: Sudden free fall of rocks from cliffs.

75
Q

Initiation of rivers

A
  • Water moves downslope over the surface = overland flow –> Sheetflow – thin film over the surface —>Rills – small grooves eroded into the soil by water —-> Gullies – rills eroded into larger features —-> Streams – water flow in valley floors fed by gullies —-> Rivers – larger systems fed by many streams
76
Q

Drainage Basin

A
  • Also called a watershed
  • The land area that feeds a
    particular river system
  • Separated by high ground
    called ridge
77
Q

Continental
divide

A
  • Separates drainage
    basins that empty into
    different oceans/seas
    surrounding a continent
  • These major drainage
    basins are made up of
    multiple smaller
    drainage basins
  • Size of drainage basin
    impacts available water
    resources
78
Q

Stream gradient

A
  • Slope of the channel
  • Drop in elevation over a distance
  • Generally steeper slope at the headwaters and shallower
    downstream
  • the gradient determines how fast the water will flow
79
Q

Base level

A
  • Lowest level that a stream can erode its valley to
  • Ultimate base level = sea level
  • Local base level can limit regional erosion (e.g. lakes,
    dams)
80
Q

Stream discharge (Q)

A
  • Discharge (or runoff) is the
    streamflow volume
    passing a point (e.g., outlet of a
    watershed) in a
    given unit of time.
  • Discharge is calculated as:
    Q = w × d × v
  • where w is width and d is depth for a specific
    cross-section of the channel, and v is the velocity.
81
Q

The Hydrograph

A
  • Base flow: low discharge during dry periods, from groundwater
  • peek flow: Highest discharge after rainfall
  • Lag time: delay between rainfall and peek flow, influenced by watershed surface
82
Q

erosion

A
  • Erosion in fluvial systems is the process by which
    water dislodges, dissolves, or removes weathered
    surface material.
  • Affected by discharge and the channel gradient
83
Q

Hydraulic action

A
  • Performed by water alone
  • The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks
    and gradually wears it away.
84
Q

Abrasion

A
  • rocks carried along by the river wear down the
    river bed and banks
  • Rocks have to be a stronger material than the
    bed
85
Q

Attrition

A
  • Rocks being carried by the river smash together and
    break into smaller, smoother and rounder pieces of
    rock.
86
Q

Corrosion/solution

A
  • Rocks and
    sediments dissolved
    by acid in the water
  • Chemical
    weathering
  • E.g. limestone,
    soluble salts
87
Q

Transportation/sediment load

A
  • Suspended load: light, fine material is carried
    within the river flow as long as velocity >0
  • Traction: large boulders and rocks are rolled
    along the bed
  • Saltation: small pebbles and stones are bounced
    along the bed
  • Solution load: dissolved load is carried along
    with the river flow.
88
Q

Flood sediment
transport

A

Larger discharge = larger
erosion and transport rates
* Degradation = channel
erodes (i.e. when flood water
build)
* Aggradation = deposition (i.e.
flood waters drop, energy
reduced and sediment
accumulates at the bed)

89
Q

depostion

A

landforms of material caused by river meanders

90
Q

river meanders

A
  • Where channel slope is
    gradual
  • Finding the path of least
    effort/resistance
91
Q

Floodplains

A
  • flat, low-lying area adjacent to a
    channel
  • subjected to recurrent flooding when
    flow is high
  • Receding water leaves alluvial deposits
92
Q

levees

A

-formed when rivers overflow and deposit sediment along banks
- create natural ridges that reduce future flooding but can trap floodwater

93
Q

Alluvial fans

A
  • Found in arid areas where streams exit mountains
  • Flash floods slow down on flat valleys, dropping sediment in layers at the mountain base.

Arid: very dry with little no rainfall, making it difficult for plants to grow. common in desserts

94
Q

Delta

A
  • At the mouth of the river where it reaches the base level
  • River slows down quickly as it enters a lake or the ocean
  • Reduced energy = deposition of sediment
  • Deposition plain = delta

Geo 102 (3 decks)

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