Physical and Ecological Processes

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Physical and Ecological Processes

• SOL WG.2b

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Plate Tectonics

• The surface of the earth is constantly changing
  due to plate tectonics and erosion and
  weathering.
• The surface of the earth looks like one
  continuous piece but it is actually broken into
  several large pieces that fit together like a
  jigsaw puzzle. Each piece is called a plate and
  when two plates come into contact it is called a
  plate boundary.

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Plate Tectonics

• Plates touch each other in four basic ways
• Divergent Boundaries
• Convergent Subduction
• Convergent Collision
• Transform

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Divergent Boundaries

• Divergent boundaries are often located at deep
  sea trenches such as the Mid-Atlantic Trench.
  The plates pull apart and as they pull apart
  magma comes to the surface and makes new crust.

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Convergent Subduction

• Convergent subduction is when two plates crash
  together and one plate is forced under the other
  one. This happens most often when oceanic plates
  collide with continental plates.

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Convergent Collision

• Convergent collision is when two plates crash
  together and they both rise into the area. This
  type of boundary often creates mountain ranges.

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Transform

• A transform boundary is when two plates slide
  past each other, causing a fault or fracture in
  the crust. One example of a transform boundary
  is the San Andreas Fault in California.

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Volcanoes

• Earthquakes and volcanoes can occur anywhere on
  the surface of the earth, including underwater,
  but they are more common at plate boundaries.

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Volcanoes

• Sometimes volcanoes occur far from plate
  boundaries. These areas are called hot spots. A
  good example of a hot spot is the formation of
  the Hawaiian Islands in the middle of the
  Pacific. Magma burned through the crust under
  the ocean and formed a group of islands.

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Volcanoes

• There is an are around the Pacific Ocean where
  many plates come together known as The Ring of
  Fire. This area has many active and dormant
  volcanoes and volcanic eruptions are frequent.

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Volcanoes

• Scientists cannot predict when volcanoes will
  erupt. Unfortunately, people usually live near
  volcanoes because volcanic ash is extremely
  fertile and good for farming.

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Earthquakes

• Earthquakes are more common at plate boundaries.
• The center of an earthquake on the surface of the
  earth is called the epicenter.
• A seismograph is a device that detects if an
  earthquake has occurred.
• The Richter Scale is a scale used for measuring
  the intensity of an earthquake.
• http//video.nationalgeographic.com/video/environm
  ent/environment-natural-disasters/earthquakes/eart
  hquake-101/

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Tsunami

• Tsunamis are giant waves caused by earthquakes or
  volcanic explosions. Usually, tsunamis come in
  series of waves and they can travel hundreds of
  miles an hour.
• Tsunamis can be detected with an early warning
  system but not all countries have the money to
  install them.

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Tsunami

• See a tsunami here
• http//video.nationalgeographic.com/video/environm
  ent/environment-natural-disasters/tsunamis/tsunami
  -101/

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Humans and Earthquakes

• Humans cant predict earthquakes but they can
  build better buildings that will withstand the
  effects of an earthquake.
• Humans can also build early warning systems that
  will detect tsunamis and warn people farther away
  from the epicenter of the wave.

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Erosion and Weathering

• The surface of the earth is also being formed by
  erosion and weathering.
• Weathering breaks rocks into smaller pieces.
• Erosion moves pieces of rock or dirt.

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Weathering

• There are two types of weathering mechanical and
  chemical.
• Mechanical weathering is caused by ice and
  vegetation. When water freezes in cracks of
  rocks it will slowly break the rock apart. The
  roots of trees and plants will slowly break apart
  rocks also.
• Chemical weathering is a chemical reaction
  between water and certain types of rock such as
  limestone that usually makes caves.

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Erosion

• After rocks have been broken into smaller pieces
  the debris is moved by erosion. The agents of
  erosion are

A. Wind
B. Water
C. Ice
D. Gravity
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Erosion

• Erosion has natural causes and human causes.
• People can take steps to prevent erosion by using
  nets, covering exposed earth with straw, and
  replanting vegetation.

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Floods

• Floods happen when there is too much rain and
  rivers overflow their banks. Floods are natural
  but as human population grows there are more
  people that live in areas that are frequently
  flooded.
• People can try to prevent floods by building
  embankments or levees.

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Floods

• Typically, areas that are low in elevation and
  near rivers or the mouth of rivers experience
  floods. A few areas that have floods are
• Along the Mississippi River in the U.S.
• Bangladesh
• Parts of Eastern China

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