Dynamic Earth

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Dynamic Earth

• Plate Tectonics, Earthquakes, Subduction, and
  other significant events

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Earth is a System

• Integrated system consisting of rock, air, water,
  and living things that all interact with one
  another--Biosphere
• Geospheresolid part
• Atmospheremixture of gases to make air we breath
• Hydosphereall water on or near Earths surface

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Discovering Earths Interior
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What is the Lithosphere?

• The crust and part of the upper mantle
  lithosphere
• 100 km thick
• Less dense than the material below it so it
  floats

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What is the Asthenoshere?

• The plastic layer below the lithosphere
  asthenosphere
• The plates of the lithosphere float on the
  asthenosphere

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Plate Tectonics
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Global Tectonic Movement
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Causes of Plate Tectonics
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Convection Currents

• Hot magma in the Earth moves toward the surface,
  cools, then sinks again.
• Creates convection currents beneath the plates
  that cause the plates to move.

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Features of Divergent Boundaries

• Mid-ocean ridges
• rift valleys
• fissure volcanoes

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Mid-Atlantic Ridge
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Sea Floor Spreading
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Hypothermal Vents
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Pillow Lava forms when magma cools in water. This
is evidence of volcanic activity!
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This shows you the age of the sea floor. The red
areas are new rocks and the blue areas are the
oldest oceanic rock.
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Iceland is spreading open on the Mid-Atlantic
Ridge!
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Can you see where the Mid-Atlantic Ridge bisects
Iceland? This is a rift valley!
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Subduction is a process where the ocean floor
sinks back into the mantle at a deep ocean trench.
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Convergent Boundaries

• Boundaries between two plates that are colliding
• ? ?
• There are 3 types

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Type 1

• Ocean plate colliding with a less dense
  continental plate
• Subduction Zone where the less dense plate
  slides under the more dense plate
• VOLCANOES occur at subduction zones

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Aleutian Islands, Alaska
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Type 2

• Ocean plate colliding with another ocean plate
• The less dense plate slides under the more dense
  plate creating a subduction zone called a TRENCH

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Type 3

• A continental plate colliding with another
  continental plate
• Have Collision Zones
• a place where folded and thrust faulted mountains
  form.

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Transform Fault Boundaries

• Boundary between two plates that are sliding past
  each other
• EARTHQUAKES along faults

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Earthquake Belts
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Earthquakes

• An earthquake is the shaking and trembling that
  results from the sudden movement of part of the
  Earths crust.
• The most common cause of earthquakes is faulting.
  During faulting, energy is released. Rocks
  continue to move until the energy is used up.

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Tsunamis

• Earthquakes which occur on the ocean floor
  produce giant sea waves called tsunamis.
  Tsunamis can travel at speeds of 700 to 800 km
  per hour. As they approach the coast, they can
  reach heights of greater than 20 meters.

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Focus

• Most faults occur between the surface and a depth
  of 70 kilometers.
• The point beneath the surface where the rocks
  break and move is called the focus. The focus is
  the underground origin of an earthquake.

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Epicenter

• Directly above the focus, on the Earths surface
  is the epicenter. Earthquake waves reach the
  epicenter first. During an earthquake, the most
  violent shaking is found at the epicenter.

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Ring of Fire
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Pacific Ring
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Seismic Risk Map of the U.S.
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• http//earthquake.usgs.gov/learning/animations/

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Formation of a Volcano
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Volcanic Eruptions

• During volcanic eruptions, many rock fragments
  are blown into the air. The smallest particles
  are called volcanic dust. (less than 0.25 mm)
• Volcanic Ash ( 0.25 -5mm) falls to the Earth and
  forms small rocks.
• Volcanic bombs (a few cm to several meters) are
  molten and harden as they travel through the air.

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Cinder Cone Volcano
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Shield Volcanoes
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Mount Vesuvius-composite volcano
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Composite Volcano
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Effects of Volcanic Eruptions

• Volcanic Ash mixing with watter produces mudflows
• Volcanic Ash buries crops
• Volcanic Ash enters the troposphere and sometimes
  the stratosphere impacting amount of sunlight and
  temperatures on Earth

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Erosion

• Water erosion by rivers and oceans dramatically
  changes the Earths surface
• Wind erosion blows away top soil and erodes soft
  rocks, such as sandstone.

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Atmospheric Layers
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Structure of the Atmosphere
Thermosphere
Mesosphere
Ozone Maximum
Stratosphere
Troposphere
Temperature
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• Nitrogen 78
• Oxygen 20
• Argon 0.9
• CO2 0.04
• Water Vapor 1

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Thermosphere

• Absorbs harmful solar radiation resulting in the
  Aurora Borealis or Northern Lights

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Atmospheric Circulations
Source Wikipedia
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Energy received at the surface depends on
1) Sun angle with respect to surface. 2) Path of
solar radiation through the atmosphere.
Source Wikipedia
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Solar Radiation Entering the Atmosphere

• Absorbed by gases and clouds goes to heating
  (19)
• Scattered and Reflected by Gas Molecules,
  Clouds, Aerosols, and the Earths surface (30)

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Source Ahrens, C. D., 2008 Essentials of
Meteorology, An Invitation to the Atmosphere (5th
Edition)
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Earths Energy Balance
Earths overall average equilibrium temperature
changes only slightly from year to year.
A balance exists between incoming solar energy
(shortwave radiation) and outgoing energy from
Earth to space (longwave radiation).
Source Ahrens, C. D., 2008 Essentials of
Meteorology, An Invitation to the Atmosphere (5th
Edition)
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Without greenhouse gases, the average surface
temperature of the Earth would be 18 C
No greenhouse gases (only permanent gases)
The current atmosphere (with greenhouse gases)
Source Ahrens, C. D., 2008 Essentials of
Meteorology, An Invitation to the Atmosphere (5th
Edition)
33 C difference
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Global Average Energy Balance
Top of Atmosphere Energy Balance
342 107 235
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107
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Incoming Solar Radiation Shortwave
z
Outgoing Long-wave Radiation
Reflected Shortwave radiation
Atmosphere Energy Balance 67 350 24 78
324 165 30
Reflected Shortwave radiation by Clouds
Aerosols and Gases
Long-wave Radiation from Clouds
Long-wave Radiation Atmospheric Window
Long-wave Radiation from Atmosphere
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Absorbed Shortwave radiation by Atmosphere
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Latent Heat
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350
Longwave Radiation Absorbed by Atmosphere
Sensible Heat
Long-wave Radiation Emitted by Atmosphere
Reflected Shortwave radiation by Surface
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Longwave Radiation Emmited by Surface
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Evapo- transpiration
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Thermal heating
Absorbed Shortwave radiation by Surface
Conduction
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Surface Energy Balance 168 390 324 24
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Greenhouse Effect Animation

• http//earthguide.ucsd.edu/earthguide/diagrams/gre
  enhouse/

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Terrestrial Ecosystems are an

• Integral part of global carbon system
• Plants take in and store carbon dioxide from the
  atmosphere through photosynthesis
• Below ground microbes decompose organic matter
  and release organic carbon back into the
  atmosphere

www.bom.gov.au/.../ change/gallery/9.shtml
Cycle shows how natures sources of CO2 are self
regulating that which is released will be used
again Anthropogenic carbon not part of natures
cycle is in excess
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The Worlds Water

• 97 Salt Water
• 2.5 Frozen Fresh Water
• .5 Usable Fresh Water

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Hydrosphere

• All water on or near the Earths surface
• Includes water in oceans, lakes, rivers,
  wetlands, polar ice caps, soil, rock layers
  beneath Earths surface and clouds.

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The Water Cycle
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Water Cycle
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Ocean circulation
Source NOAA
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Source Wikipedia
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Layers of the Ocean
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Global Ocean Temperatures
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Storm Watch, Sept 1, 2011
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North Atlantic Coast Sept 1, 2011
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Freshwater

• Freshwater is defined as having a low salt
  concentration usually less than 1.
• Plants and animals in freshwater regions are
  adjusted to the low salt content and would not be
  able to survive in areas of high salt
  concentration (i.e., ocean).

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Streams and rivers

• These are bodies of flowing water moving in one
  direction.

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Wetlands are among the most productive ecosystems
in the world, comparable to rain forests and
coral reefs.
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Watersheds help the ecosystem
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Aquifers

• Aquifers- permeable materials that carry
  groundwater

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Artesian Formations

• Artesian Formation- aquifer under nonporous
  layers holds groundwater
• Artesian Wells- release water from Artesian
  formations

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Recharge Zone
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Biosphere
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Closed System

• Energy enters the system but matter does not
• Earth is still a closed system with respect to
  matter but is still an open system with respect
  to energy

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Open System

• Both matter and energy are exchanged between the
  system and the surrounding environment.

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