Transcript Extreme Earth - Introduction

ERSC 1P92 Extreme Earth
Final Exam:
Wednesday, December 3, 2008
1400h – 1600h
WCIBDS - Ian D. Beddis Gym
110 multiple choice or “figure” questions to be
answered on SCANTRON sheets
Questions will be based on material covered over
the entire course.
The nature of scientific ideas
Speculation
Hypothesis
Theory
Law
Geology 001: the basics
Igneous Rock
Sedimentary Rock
Fossils
Metamorphic Rock
The geologic cycle
A Brief History of Geology
Herodotos
Aristotle Theophrastus St. Thomas Aquinas
Leonardo da Vinci
James Ussher
Neptunism versus Plutonism
Abraham Werner
James Hutton and the Principle of Uniformitarianism
Georges Cuvier
Charles Lyle
Catastrophism in the
th
20
Century
The Origin of the Solar System
Nebular Hypothesis
The Planets of the Solar System
The early history of the Earth
How did the Moon form?
Comets, Asteroids and Meteoroids
Comets: dust and ice.
Asteroids (rocky bodies)
Meteoroid
Meteor
Meteorite
Bolide
The Risk of Space Objects to Humans
K/T boundary impact
Tunguska Event
Comet SL-9 impact on Jupiter
What is the frequency of
impacts with Earth?
Near Earth Objects
What happens when a meteoroid or asteroid reaches the
Earth?
Heat wave
Pressure wave
Impact crater formation
Evaluating the
risk of asteroid
impacts.
Impact craters on Earth
How they form.
Crater anatomy.
Major craters on Earth.
Plate Tectonics defined.
What did Plate Tectonics replace?
Contracting Earth Theory
Alfred Wegener and Continental Drift.
Evidence
Theory
Outcome
Geomagnetism
Earth’s Magnetic Field
Geodynamo
magnetic declination
secular variation
Orientation of the Earth’s
magnetic field.
Magnetization of rocks
Remnant magnetic signature (RMS)
Magnetic Anomalies
Apparent Polar Wandering
Apparent polar wandering paths pointed to continental drift.
Polar reversals
Sea Floor Stripes
and Sea floor
Spreading
Plate Tectonics
Structure of the Earth
USGS
Plate Boundaries
Oceanic Ridge
– Divergence
Oceanic Trench
– Convergence
Transform Margins
– Horizontal slip
But what drives plate tectonics?
Anatomy of an Earthquake
Earthquakes
What is an Earthquake?
Shockwaves generated by energy released as adjacent rock
bodies suddenly move.
Types of Shockwaves
P-waves (primary waves)
S-waves
(secondary or shear waves)
L-waves (surface waves)
Intensity
Magnitude
Damage due to earthquakes
Surface vibration
Landslides
Liquefaction
Tsunamis
Distribution of Earthquakes
1. Along oceanic trenches.
2. In regions of continental collision.
3. Along oceanic ridges and transform faults.
4. Within plates, well away from plate margins.
Predicting earthquakes
Long term prediction
Recurrence rates
Seismic Gaps
Short term prediction
precursor events
Seismic wave velocities
Ground level deformation
Groundwater Chemistry
Microearthquake swarms
Direct Sensors
Animal warnings
The Great Canadian Earthquake???
(Evidence for a southern BC megaquake)
Early evolution of the Earth and its atmosphere.
Formation of the Earth’s core and crust.
The Earth’s
atmosphere and the
evolution of early life.
Climate versus Weather
Weather: the condition of the atmosphere at a particular point in space
and time.
Climate: the average weather for a defined region.
Climatic Radiative Balance and
Radiative Forcing
Climate Change Over Geologic Time
Conditions in the Cretaceous
Much warmer as CO2 levels were
elevated due to an increase in volcanic
activity.
Climatic fluctuation over the
Tertiary and Quaternary periods.
4 glacial periods
Global warming and glaciers
Milankovich Cycles
Mild winters, abundant
snow and cool summers.
Glaciers develop.
Cold, dry winters, hot summers.
Glaciers will not develop.
Carboniferous/Permian
Cooling due to CO2 removal by extensive
weathering.
Snowball Earth
That 600-700 million years ago the Earth was effectively
covered by glacial ice, including 500 to 1500 m thick sea ice
cover.
Volcano: A mound of material that is extruded to the Earth’s
surface from a vent that is connected to a magma chamber via
a feeder conduit.
SiO2 content controls viscosity of the
magma which in turn controls the
amount of gas in the magma and its
explosivity.
Types of volcanic deposits
Lava: very fluid, low viscosity
magma at the Earth’s surface.
Pahoehoe
Aa
Pillows
Pyroclastic material
Tephra: Ash, lapilli, blocks and bombs.
Tuff
Ash fall
Lahar
Nuée Ardente
Shield volcanoes:
dominated by lava flows.
Cinder cones:
Isolated cones dominated by
pyroclastics.
Stratovolcanoes:
mixture of lavas and
pyroclastics.
Prediction of Volcanic Eruptions
Long-term prediction
Identify the distribution, frequency, style of eruption, etc.
Determine local risks to specific hazards.
Short-term prediction
Gas emissions: rates of emission and type of gas changes in
some volcanoes.
Surface tilting: recognition of changes in the land
surface due to building pressure in the conduit.
Earthquakes: generated as the magma moves up the
feeder conduit to the vent.
The impact of volcanic eruptions
Global Climate Change
Volcanic Explosivity Index
Major Historic Eruptions
Mt. Pelée (1902)
Tambora (1815)
Krakatoa (1883)
Krakatoa (535 AD)?
Super Volcanoes (>1,000 km3 of ejecta)
Toba
Yellowstone
Volcanoes in Space