Transcript Physical and Ecological Processes

Physical and Ecological
Processes
SOL WG.2b
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.
Plate Tectonics
 Plates touch each other in four basic
ways:
A. Divergent Boundaries
B. Convergent Subduction
C. Convergent Collision
D. Transform
Divergent Boundaries
Divergent boundaries are often located
at deep sea trenches such as the MidAtlantic Trench. The plates pull apart
and as they pull apart magma comes to
the surface and makes new crust.
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.
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.
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.
Volcanoes
Earthquakes and volcanoes can occur
anywhere on the surface of the earth,
including underwater, but they are
more common at plate boundaries.
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.
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.
Volcanoes
Scientists cannot predict when
volcanoes will erupt. Unfortunately,
people usually live near volcanoes
because volcanic ash is extremely fertile
and good for farming.
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/environment/environ
ment-natural-disasters/earthquakes/earthquake-101/
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.
Tsunami
See a tsunami here:
http://video.nationalgeographic.com/vide
o/environment/environment-naturaldisasters/tsunamis/tsunami-101/
Humans and Earthquakes
Humans can’t 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.
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.
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.
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
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.
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.
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:
A. Along the Mississippi River in the U.S.
B. Bangladesh
C. Parts of Eastern China