Washington State Chapter 1 by HC121104093010


									Washington State
  Chapter 1
 Geologic History
               Geologic Processes
Plate        An idea used by geologists (people who
tectonics    study the natural processes & history of
             the Earth) to describe how land and
             landforms such as mountains, hills,
             plateaus, etc… are created and
             positioned throughout the world.
Crust        The outer layer of the Earth that we live on
Mantle       Directly beneath the crust; extremely hot &
             melt rocks to form molten magma (lava)
Outer core   Below the mantle; even hotter than the
             mantle; made up of melted iron & nickel
Inner core   Below the outer core/center of the Earth;
             composed of same material as the outer
             core but is the hottest layer of all.
         Geologic Processes
• All layers under the crust are extremely hot
• The rule: heat (whether it’s boiling or hot air)
  generally rises
• Hot molten magma rises to the surface –
  when it reached the surface, it cracked, or
  fragmented, the crust into many pieces
• Geologists call these pieces tectonic
             Tectonic Plates

• Like puzzle pieces; fit together to form a
  picture but not one solid piece
• Made of solid rock
• Sit on top of the mantle (made of molten
             Tectonic Plates
• Because of this tectonic plates are not in a
  constant position
• They float around, moving slowly over millions of
  years, crashing into one another – movement is
  caused by the rising of molten magma
• Movement of the plates causes the formation of
  major physical landforms (mountains, hills,
  plateaus, etc…)
           Tectonic Plates – 3 types
• Divergent – move away from
  each other; usually occurs on
  floor of ocean; result of magma
  rising through the plates; magma
  hits the water & becomes solid
  rock called volcanic ridge
• Transformant – two plates
  heading in opposite direction
  brush against each other; sliding
  motion; most of the time it’s a
  horizontal movement
• Convergent – direct head on
  collision - 2 types of plates
  involved: Oceanic plates (in the
  ocean) Continental plates (ones
  that continents sit on)
    Tectonic Plates of the World
Earth has 30 plates that drift on the mantle – throughout history the number of
                               plates has changed.
          Plate Movement
• Greatly affected Washington’s landscape
• Waves of the Pacific Ocean used to crash
  against western side of Rocky Mtn’s
• Juan de Fuca plate—helped to form the
  Cascade Mtn’s
    Mountain Building Process
Results of tectonic activity is important to
understand – especially living in WA state –
as it is the reason behind all the mountains

1) UPLIFT – a heavier plate pushing up
underneath a lighter plate, thereby pushing
the land of the lighter plate up.
   Mountain Building Process
2) Volcanic Activity – one plate pushes up
another (not only land but magma)
the result is the creation of volcanoes
volcanoes build mountains by erupting
lava & ash
         Volcanic Eruptions
• 2 types of eruptions:
  vertical               lateral
• Most visible natural force affecting WA
• Most recent LARGE eruption occurred at
  Mount St. Helen’s in May 1980

• Dormancy – term used to describe time
  between eruptions
May 1980
July 2011
        Dormant Volcanoes
• In WA state: Mt. Rainier, Mt. Adams, & Mt.
• When these erupt, the Mt. St. Helen’s
  eruption will have been child’s play
• Native American folklore tells stories of
  these now dormant volcanoes
Ring of Fire

• Name
  faults and
  the area
• Happen when seismic waves travel through the
  surface of the Earth’s crust, causing the land to
  shake & vibrate
• Energy released from a single point called the
• Occur along active fault lines (faults occur when 2
  different plates of crust touch)
• Faults grind and move slowly against each other
• When a fault gets stuck, pressure builds & when it’s
  released an earthquake happens
• Charles Richter seismologist developed the machine that
  records ground movement during an earthquake – called a
  Richter Scale
      uses numbers 1-10 to measure
      1 = weakest earthquake
      10 = strongest earthquake
      for every increase of a whole number on the Richter
        scale, the intensity of the earthquake increases 10
• Thanks to Richter we can: gain knowledge on how ground
  moves & be better prepared for future earthquakes
Largest earthquake in N. America – Anchorage, Alaska
1964 measuring 9.2 on the Richter scale
Nisqually Earthquake on Feb. 28, 2001 measured a 6.8
on Richter scale
                   Forces of Ice
• Ice is another major factor that has formed WA state’s
• Continental glaciers (thick, massive ice sheets slowly
  moving across the landscape over long period of time)
  moved as far south as Olympia and the Columbia River

• Glacier branched out into lobes (3 of them in WA state)
      Puget Lobe, Okanogan Lobe & Polson Lobe

• Avalanches & alpine glaciers erode slopes of WA volcanoes
  and mountains
             Forces of Ice
• Alpine Glaciers – located on the sides of
  mountains or in mountain ranges
they break rock & carry it along its path
down the mountains
• 1/3 of all alpine glaciers in the U.S. are
  found in WA state (Mt. Rainier has 26 of
• Natural agents such as water, ice, wind, and waves
  wear away landscapes, thus altering them.
• It removes pieces of rock, sand, & soil from one
  place and depositing these same substances in
  another location.
       Ex: river cuts away at its bank, picks up
        rocks & soils which are deposited down river.
• Through erosion, landscapes are destroyed, while
  others are built up.
• The rapid collapse of debris, such as dirt,
  rocks, and boulders, from a higher
  elevation to a lower elevation.
Changes in landscapes can be:
damming streams into lakes
widening valleys
altering mountainsides
• Washington’s numerous physical features
  are all visual reminders of the power of
  land, rock, ice, water, and wind.

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