Final (PPTs: After Midterm) Flashcards
Skipped Some Slides (Oct 23-25)
Earth’s magnetic field, inclination (distance from pole) and declination (direction to pole), linear magnetic anomalies
What does remnant magnetism do?
Some ancient rocks were (weakly) magnetized when formed - “Remanent magnetism”
• “Fossil compass needles”
• If age of rocks is known, remanent magnetism indicates the ancient location of the pole; apparent pole position.
What does APWP stand for?
Apparent polar wander path.
Different continents show different APWPs, so the continents must move
What is the Vine-Matthews hypothesis?
Magnetic anomalies result from remanent magnetism acquired during spreading of ocean-floor while magnetic reversals occurred.
What are some ways to measure ground shaking?
- Ancient seismic detector
- Traditional seismograph
- Seismometer
How is the intensity of an earthquake measured?
The intensity is the strength of the ground skaing at a point and depends on factors such as distance from focus. Measured through modified Mercalli scale?
How is the magnitude of an earthquake measured?
Magnitude is a measure of total energy released and is measured using a modern scale based on Richter’s. It is a log scale whereby each step on scale multiplies energy by sqrt(1000).
What are the different seismic waves?
Body waves (P):
• 3-7 km/s in the crust
• Similar to sound waves
• Compression and expansion (‘dilation’)
• Vibration direction parallel to propagation
• Pass through solid, liquid or gas.
Body waves (S):
• 1.5- 5 km/s in the crust
• Shear waves
• Vibration direction perpendicular to propagation
• Solids only
Surface waves (L/Rayleigh):
– Surface waves form when body waves reach the surface
– Slower but larger than body waves
– Cause most damage
What is the difference between epicentre and focus?
Focus is origin of earthquake and epicentre is location on surface above focus.
Describe Tsunami waves.
• Tsunami: surface waves on ocean – Low on open ocean (~ 1 m) – 600 km/hr + – In shallow water, slow down, get higher (>10 m) – Devastate coastal communities
Describe earthquakes.
- Earthquakes result from – Elastic strain followed by… – Brittle fracture (or brittle failure).
- These processes occur in cold rocks, typically < 70 km deep (>100 km at subduction zones)
What are the S and P wave shadow zones?
S: 105-180
P: 105-142
What are some ways to directly measure plate movement?
- GPS
- Re-occupied sites
- Plate movement velocities in agreement with magnetic anomalies
Skipped Some Slides (Oct 25-Nov 3)
Velocity within channel, turbulent flow upstream vs laminar. terraces, superimposed drainage, oxbow lake, natural levees, alluvial fans, delta and classification, lakes.
Small streams (tributaries) typically merge downstream. The area drained by a major river and its tributaries is a ___ ___. These are separated by ___ ___.
Drainage basin. Drainage divides.
Streams show variability in gradient, width, depth, velocity, and discharge. What happens to the former 4 as discharge increases (farther downstream)?
Width increases.
Depth increases.
Velocity increases.
Gradient decreases.
Streams show variability in gradient, width, depth, velocity, and discharge. What happens to the former 4 as discharge increases (farther downstream)?
Width increases.
Depth increases.
Velocity increases.
Gradient decreases.
What are the 2 types of stream erosion?
Downcutting and lateral erosion.
What is mass wasting and what are examples?
Mass wasting is due to gravity, with or without assistance of transporting medium.
-Creep, landslides(rotational and translational), rockfalls and avalanches, debris flow.
What is volcanically triggered debris flow called?
Lahar.
What is base level?
The level at which a stream enters the sea or a lake.
What are types of drainage patters?
Dendritic, parallel, radial, rectangular, trellised.
What rock types form steeper slopes?
Erosion-resistant.
Describe buttes vs mesa (formations formed by more stable rock)?
Mesa has a width that is substantially longer than height in comparison to Butte.
What are the different forms of sediment transport?
- Bedload (rolling, sliding, saltation)
- Suspended load
- Dissolved load (ions in solution)
What are the features on the inside and outside of a meander?
Inside is point bar and outside is cut bank. Meanders tend to migrate downstream.
What is a recurrence interval?
Frequency of past floods can be plotted, calculating the average time interval between two floods of equal magnitude.
What is channelization?
River channels are often modified for the purpose of flood control.
Down cutting may leave old floodplains as ___.
Terraces.
What are braided channels?
Habe multiple channels separated by bars. Typically form where discharge is variable and banks are easily eroded. Common in glacier-fed rivers.
In general, an obstacle to flow is necessary to produce a lake (geologically short lived). What are some causes of lakes?
– Glacial erosion & deposition
– Volcanic activity
– Tectonism
– Deposition and erosion of sediment by water (e.g. oxbow lakes in meandering river systems)
What are the typical sediments of open and closed lakes?
Open: muds, with sand near shores.
Closed: salt from evaporation.
Groundwater is likely less than ___% of Earth’s water.
1%
The elements dissolved in groundwater consist of …? (dissolve from common rock-forming mineral, varies depending on surround rock)
Chlorides, sulfates, and bicarbonates of calcium, magnesium, sodium and potassium.
Groundwater flows between pore spaces by ___.
Percolation.
Percolation flow depends on porosity and permeability of rock. What are these?
– Porosity: the percentage of the total volume of rock that consists of open pore spaces
– Permeability: a measure of how easily a solid allows fluids to pass through it
What are the zones of groundwater?
- Zone of aeration: pore spaces partly filled by water
- Zone of saturation: pore spaces entirely filled
- Water table: the surface that separates these zones
Skipped Some Slides (Nov 3-6)
Groundwater flow, recharge and discharge, springs, confined vs. unconfined aquifer, cement.
What is the Hydraulic head?
Measures pressure difference driving flow.
What are aquifers and aquicludes?
Aquifers are porous rock units that have enough permeability to supply water at a rate useful to humans
An aquiclude is an impermeable unit with permeability low enough to form a barrier to flow
When will a cone of depression form (unconfined aquifer)?
If the rate of withdrawal exceeds the rate of local groundwater flow in an aquifer.
If it has high hydrostatic pressure, it is an ___ aquifer, freely flowing.
Artesian (confined aquifer).
Water level rises in wells due to the hydraulic head, reaches level close to water table in recharge area (potentiometric surface).
___ dissolved in rainwater makes it slightly acidic.
CO2.
Groundwater solution creates distinctive landscape features in limestone and other soluble rock types. Name some.
- Cave systems are very large pore spaces formed by solution
- Sinkholes form where the roof of a cave collapses
- Karst topography is characterized by numerous sinkholes and/or pillars of rock isolated by solution
Mineral deposits (typically calcite) form in air-filled portions of caves. What are they?
- Stalactites resemble icicles hanging from ceiling
* Stalagmites are corresponding pillars growing from cave floor
Skipped Some Slides (Nov 6-8).
Annual snow line, glaciers as envir. records, flow of glaciers (temperate and polar), deforming stress (alignment of crystals). terminus of glaciers, accumulation and ablation, equilibrium line, mechanisms of erosion (plucking = main), sea ice effect on ocean circ. and envir. (albedo)
What affects the location of the snow line?
Temperature and moisture.
What is the defn on glaciers?
Ice masses that flow under the influence of gravity are glaciers. Form from snow that has compacted until it is so dense it is impenetrable to air (considered a rock).
What are the 6 types of glaciers?
– Cirque glacier – Valley glacier – Fjord glacier – Ice cap – Ice sheet – Ice shelf
Greenland and Antarctica include ___% of Earth’s glaciers and reach 3000 m thick.
95%
The most recent glaciation ended …?
~10 ka. However, there have been many glacial and interglacial periods in last 2 Ma.
How does glacier ice form?
- Evaporation occurs at points of snowflakes
- Moisture freezes between points
- Granular snow is called firn
- Snow gradually loses interstitial air to become glacier ice
In glaciers, grain size ___ downward.
Increases as ice recrystallizes.
Top ___ m of glacier is brittle, does not flow.
50m
What are the temp profiles are the two types of glaciers?
– Polar glacier is below freezing point throughout
– Temperate glacier is close to freezing point, and has liquid water at base
Why might glaciers experiences surges (several km/yr)? Rapid retreats?
- Surges may be related to water at base buildup
- rapid retreat may occur when fjord glaciers retreat from a sea-floor shoal and experience calving
What are some erosional surface features/landforms of glaciers?
- Rock surfaces with striations and chatter marks
- U-shaped valleys
- Cirques
- Hanging valleys
- Arêtes
- Horns
What are some glacial deposits?
- Till
- Terminal and lateral moraines
- Medial moraines
- Drumlins (ice sheets)
- Eskers (below)and kames (above0
Describe the formation of sea ice.
- Air temperature falls below freezing point of salty water
- Initially small needles of ice form: frazil ice
- Eventually freeze together to make continuous ice cover
- Subsequent freezing adds ice to base • Melting and sublimation removes ice from surface
- Upward movement of ice – typically 45 cm/yr
What are the two zones of ice?
Perennial and seasonal.
Describe some features of sea ice movement.
- Sea ice typically moves several km per day
- Ice may crack producing leads of open water
- Leads may freeze to make a complex mosaic
- Convergence of ice masses produces pressure ridges
- Large openings in sea ice are Polynyas
What does AABW and NADW stand for?
Antarctic Bottom Water
North Atlantic Deep Water
Permafrost, permanently frozen ground, contains ice that froze during glacial ages. It extends down ___ m in Siberia and ___ m in Canadian arctic.
1500m
1000m
Where is permafrost thickest?
In areas not covered by insulating ice sheets.
What is the active layer?
Active layer on top of permafrost melts in summer (wet/mobile). Underlying permafrost is impermeable.
Ocean covers ___% of Earth’s surface.
71%
Give the properties of the ocean water depth.
- Maximum depth 11 km
- Average depth 4.5 km
- Volume of ocean water 1.35 x 10^18 m^3
- Varies over time (melting of ice)
What is the total salinity of the sea (contains a variety of ions)?
~3.5% or 35 psu.
Sodium 30.62% and chloride 55.07%
What is the origins of dissolved ions in oceans?
- Introduced by rivers as dissolved load
* Introduced from submarine volcanic activity
Skipped Some Slides (Nov 8-20)
Changes in composition of seawater over time, tides, flood and ebb currents. changes in relative sea level (eustatic/worldwide and local), deltas, beaches, descriptions of continental shelves, slopes, rises.
What is the thermocline and halocline and pycnocline?
- Cold water is denser, sinks
- Thermocline is zone of rapid temp. change
- Saline water is denser, sinks
- Halocline is region of rapid salinity change. (Not present everywhere)
- Pycnocline is zone of rapid density change
What are the forces driving ocean currents?
- Air currents (wind) on surface
- Sinking of denser (cold or saline) water
- Rotation of Earth
What are the thermohaline currents?
• High salinity descending currents – AABW Antarctic Bottom Water – NADW North Atlantic Deep Water • North flowing surface currents • AAIW (Antarctic Intermediate Water)
Due to the Coriolis effect, the surface of solid Earth is rotating slightly about vertical axis (everywhere except at equator). In what directions?
- Counterclockwise (CCW) in N hemisphere – Clockwise (CW) in S hemisphere
- Objects moving in a straight line appear to curve relative to solid Earth beneath them – Right in N hemisphere – Left in S hemisphere
What is the Ekman effect?
Because of Coriolis effect, wind driven current in N hemisphere is slightly CW of actual wind direction. Deeper currents are progressively rotated CW.
Overall average water movement is ___ CW of wind.
90º
What is the Ekman transport.
Based on wind direction, current is 90º.
• Upwelling where Ekman transport is offshore
• Downwelling where Ekman transport is onshore
Surface circulation is dominated by Coriolis-driven ___.
Gyres.
Deep circulation is driven by density (___) effects.
Thermohaline.
Waves result from wind action on water surfaces. Motion of water follows looping ___. Motion decreases downward to ___.
Orbitals.
Wavebase.
Define wave height and wave length.
Wave height: vertical difference between crest and trough next to it, typically less than 1 m (L/2)
Wave length: resultant difference between 2 subsequent crests (L)
Wave orbitals flatten in shallow water due to drag on sea floor. Wave crests overtake deeper water in ___ zone.
Surf zone.
Describe longshore transport.
- Waves approaching shore obliquely
- Oscillating motion is converted to longshore current
- Sediments are carried along shore: longshore drift
Most areas experience high tide every ~___ hrs. Tide rises and falls
~12 hrs 50 mins.
<1m.
The Sun also causes tides, but only ~half as effectively as the moon. What are spring and neap tides? (14 day cycle from spring to spring)
Spring tides are when the sun and moon are in-line and effects are combined. Neap tides are when Sun and moon are at 90 degrees and effects are opposed.
Define estuaries.
Wide-mouthed rivers typically form in areas of high tidal range. Low animal diversity due to fluctuations in freshwater conditions.
Descibe carbonate shorelines and atolls.
- In clear tropical seas, organisms build reefs: structures of Calcium Carbonate built up from sea floor
- Deposition can keep pace with tectonic subsidence
- Produces atolls around former volcanic islands
- Forms lagoons, recall oolites
What are some type of sediment gravity flows on continental slopes and rises?
– Debris flows: particles supported by plastic mud
– Turbidity currents: particles supported by fluid turbulence
Continental shelves go to depths of
<200m.
What are submarine fans?
Sediment deposits on the continental rise. Alluvial fan equivalent of deeper water settings.
What are pelagic sediments and describe the three types.
Pelagic sediments: deposited far from land influence.
• Calcareous ooze: Remains of planktonic (suspended) organisms with calcium carbonate skeletons
• Siliceous ooze: Similar, but radiolarian instead of plankton and silica instead of calcium carbonate
.• Deep-sea clay: most common clastic sediment in deep sea
Lowest ___ km contains 50% of atmosphere. Lowest ___ km contains 99% of atmosphere.
5.5 km
32 km
Skipped Some Slides (Nov 20-24).
Barometers (Hg and Aneroid), Dalton’s law of partial pressures, latent heat, saturation, distribution of high and low pressure (polar and tropic highs and lows), polar front
What is average pressure at sea level?
101.325 kPa, defn of isobars
How does pressure vary?
Decreases upwards and varies slightly from place to place.
Define temperature vs heat.
- Temperature measures average kinetic energy of molecules
* Heat refers to total energy of all molecules
Atmosphere is divided on basis of temperature into 4 layers. What are they? (~500 km above surface merges with space)
Troposphere (temp decreases with altitude):
• ~16 km thick at equator
• ~10 km at poles
• Top surface is tropopause
• Heated from below, by heat reradiated
• Contains most weather
Stratosphere (increases):
• Extends from top of troposphere to ~50 km
• Temperature increases upward due to absorption of solar UV energy by ozone O3
• Upper boundary is stratopause
Mesosphere (decreases):
• Temperature decreases upward to ~80 km
• Upper boundary is Mesopause
• Coldest layer
Thermosphere (increases):
• Heating by particles from Sun
• Temperature is high but molecules are scarce, so total heat content very low
• 80-~500 km
What is adiabatic temp change (origin of chinooks)?
- As air masses rise, pressure falls, and expansion occurs
- This expansion involves conversion of heat energy into mechanical energy
- Temperature falls
What is the adiabatic lapse rate?
Rate of temperature change with elevation is 1ºC per 100 m, or 10ºC/km (reduced if moisture present and clouds form)
What are the components of the atmosphere?
• Gases – Nitrogen (78%) – Oxygen (21%) – Argon – Carbon dioxide – Water vapour – etc. • Aerosols– Water droplets– Ice particles – Solid particles • Salt • Windblown dust • Smoke particles • etc.
What are the 5 greenhouse gases?
CO2, water vapour, methane nitrous oxide, ozone
Total amount of water vapour varies between ~___% and ~___%.
~0.3% and ~4%.
Saturation pressure ___ with temp.
Increases.
What is relative humidity?
- The relative humidity is the actual vapour pressure of water divided by the saturation pressure
- If relative humidity is 100%, condensation can occur
- Relative humidity may be raised by increasing the amount of water vapour or by reducing temperature
What is the dew point?
For a given amount of moisture in the air, the dew point is the temperature at which
– The relative humidity would be 100%
– Condensation would start to occur
Adiabatic cooling of rising air is a common cause of condensation. Describe.
- Condensation releases latent heat energy, which offsets adiabatic cooling
- Lapse rate is reduced for condensing air
What is the ITCZ?
Inter tropical convergence zone. Migrates with seasons.
When flow is parallel to isobars, pressure gradient is ___ by Coriolis effect. Flow becomes a straight geostrophic flow.
Balanced.
As a result of Coriolis effect, global air circulation is broken into several cells. What are they?
- Hadley cell –pressure gradient flow
- Ferrel cell – poorly defined, circulation driven by adjacent cells
- Polar cell – pressure gradient flow
Flow near surface is not exactly geostrophic since friction reduces the Coriolis effect on pressure gradient flow. In N hemisphere, wind direction is ___ from isobars.
CCW
Ekman spirals: In N hemisphere, high pressure areas (anticyclones) have ___ outward spiralling winds.
CW.
- Low pressure areas (cyclones) have CCW inward spiralling wind.
- Opposite in S
Where are easterlies and westerlies dominant?
- Equatorial areas dominated by easterlies ‘trade winds’
- Mid-latitudes dominated by westerlies
- Easterlies predominate in polar region
Where are jet streams located?
- Mid latitude change in altitude of tropopause creates steep pressure gradient
- Strong westerly geostrophic flow is jet stream
- Located above polar front
Weather conditions are controlled by air masses up to 2000 km wide. Name the types.
– Continental polar: cold, dry
– Maritime polar: cool, moist
– Continental tropical: hot, dry
– Maritime tropical: warm, moist
Fronts are boundaries between air masses. Name the two types.
Warm front: warm advances on cold, shown with rounded tooth line
Cold front: cold advances on warm, shown with pointed toothed line
- Typical wind speeds average ___ - ___ km/hr
- Fastest average speed: ___ km/hr. (Cape Dennison Antarctica)
- Hurricane and storm winds: up to ___ km/hr
- Highest ever recorded: ___ km/hr: (Mt. Washington, USA)
10 – 30
70
335 (40 is storm conditions)
372
Skipped Some Slides (Nov 24-27).
3 factors controlling wind speed, geostrophic winds, mountain and valley winds, chinooks and related winds, nucleation energy, defn of dew and frost, lightning, tornadoes, sand transport, cross-bedding.
Friction with surfaces modifies and slows wind speeds and reduces the Coriolis effect. How much on smooth surfaces? Rough?
- Smooth surface (e.g. sea): deflection 10 - 20º
* Rough surface (e.g. forest) : deflection up to 50º
Seasonal migration of pressure belts reverses wind direction. This affects India, Australia, W. Africa. Explain monsoons in India.
- Winter: – ITCZ lies S of India – Dry NE trade winds from land
- Summer – ITCZ migrates N – SW wind from ocean brings heavy rain
Sea and Land breezes are local pressure gradient winds. Describe them.
Sea breezes: • Day: land heats faster than sea • Air rises over land: low pressure • Sea breeze blows toward land Land breezes: • Night: land cools faster than sea • Air rises over sea: low pressure • Land breeze blows toward sea
What are katabatic winds? Eg. Mistral wind in Mediterranean.
• Cold dense air accumulates over high plateau, glacier, or ice cap • Cold air spills into valley
Nucleation produces water droplets (clouds) which grow rapidly to ~___μ diameter. If more than 1 per mm^3, collisions lead to raindrops.
~20 μ
High nucleation energy inhibits ice formation down to ___ºC.
9ºC.
-10ºC to -20ºC: clouds are mixed water droplets and ice crystals. Below that, all ice.
What are the different types of cloud formation?
– Density lifting
– Frontal lifting
– Orographic lifting
– Convergence lifting
What are the 3 basic cloud types?
– Cumulus: flat base (dew point), domed top, typical of rising warm air and density lifting.
– Stratus: horizontally extensive flat layers, typical of frontal lifting
– Cirrus: wispy high clouds, typical ice-particle clouds of upper troposphere.
Where do thunderstorms form?
- Form in warm moist air masses, during daytime heating
* Especially along cold fronts where mT air contacts cP air
Tropical cyclones form 5-10º N or S of equator. Describe them.
• Require:
– Warm moist air (> 26º C over sea)
– Condensation to supply latent heat for continued density lifting
– Coriolis effect to drive rotation
• If winds >119 km/hr, hurricane status
• Naming depends on location
– Hurricane (Atlantic)
– Typhoon (NW Pacific)
– Cyclone (Australia)
• Low pressure centre raises sea level up to 9 m
• Wind may drive raised water on shore: storm surge
• Very high rainfall (>250 mm common): flooding
• Deserts:
<250 mm
250-500 mm
Belts of low rainfall correspond to regions of divergence. What are the 4 belts?
– North polar high
– North subtropical high
– South subtropical high
– South polar high
What are the 5 types of deserts?
– Subtropical – Continental – Rainshadow – Coastal – Polar
Not all deserts are ‘sand seas’ (___). Large areas have rocky desert pavement.
Ergs.
Small grains lie in zone of ___ flow: not easily Moved by wind. Larger grains enter turbulent zone and can roll, displacing small grains into turbulent zone.
Laminar.
Dust storms have visibility…?
<1km
What are Loess?
Aeolian deposits.
Skipped CLIMATE AND CLIMATE CHANGE.
- Introduction to climate
- Recorded climate change: the last two hundred years
- Longer term change: hundreds to thousands of years
- Quaternary glaciation
- Climate change over geologic time
- Causes of natural climate change
Skipped THE BIOSPHERE.
- Living processes
- Species and their classification
- Cells and their structure
- Energy and the carbon cycle
- Energy flow, biogeography, and ecosystems
- Population dynamics
- Biogeochemical cycles
Skipped EVOLUTION.
- Evidence for change in the biosphere
- Mechanisms of evolution
- Major steps in evolution
Skipped THE ANTHOPOSPHERE: NATURAL RESOURCES AND HUMANS.
- Introduction to Earth resources
- Renewable resources
- Non-renewable resources
