The Restless Earth

The Earth is alive with incredible forces both below and above.  The forces include volcanoes, tsunamis and earthquakes caused by tectonic plate shifting from underneath the earths crust.  Above the earth weather forces such as wind, rain and ice transform the land constantly over time.  Mountains are made by shifts in the earths crust only to be slowly taken down by millions of years of erosion to help constantly change the landscape on which we live.  To discover the many ways the earth is changes its important to look at each part individually to show how each does its part.

      The first important part we need to know about the earth is the make up.  Scientists believe say that the Earth’s crust is 6 to 45 miles thick in some parts.  The mantle located under the crust is 1800 miles thick and is much hotter and softer then the outer crust.  Beneath the mantle is the outer core, which is about 1300 miles thick, consists of a sea of liquid iron.  Scientists believe under the liquid core is a possibly solid iron core about 1500 miles thick.  The Earth’s crust is broken down into about thirteen large and some small plates. 

     More the 200 million years ago the continents of what we now know of North America, Africa, South America, Eurasia were all stuck together forming one large continent called Pangaea.  These continents all broke off and slowly made their way to their present location.  The reason for this slow continental drift was that these continents rest atop of the tectonic plates.  Mantles convection currents slowly turning over and over cause the movement of these plates.  These movements help form volcanoes; create new mountains over time, creation of new earth’s crusts, destruction of old earth’s crust, tsunamis and earthquakes.

     Scientists have proven that the earth creates new crust while plates move further and further away from each other.  Scientist found evidence of the creation of new crust by means of the ocean floor expanding.  They used a process called Magnetic Reversal to prove this.  When lava flows out of a newly created opening in the earth it contains small crystals that are naturally magnetized. Scientists already know that the Earth magnetic field has reversed over 300 times in the last 200 millions years. When the scientists look at the crystals in the lava the see the creation of new crust over time.  When to plates move away from each other this is called a Divergent Boundary

    The creation of this new crust is proof that the tectonic plates are moving further apart but we can also see evidence of the destruction of tectonic plates when we look at a Convergent Boundaries.  Convergent Boundaries is when one plate sinks beneath another plate (this is also called a subduction zone).  It is possible when I plate does sink beneath another plate it will melt back into magma.  This magma can slowly rise to the surface and slowly create a chain of volcanoes over time.  This movement of plates can also create new mountains.  The creation of new mountains is evident in jagged mountain chains.  Examples of these would be The Himalayas.  The Himalayas are still growing taller about 1 cm per year.  The reason we know that these mountains are fairly young, only about 30 million years old, is because the jagged form they have.  Mountains that are much older will not have the ragged forms due to weathering of wind and erosion.

    Transform plate boundaries are the third form of plate movement.  These plates scrape past each other where no other crust is being produced.  A very good example of this type of boundary is the San Andreas Fault in California.  The friction that is caused by these plates rubbing against each other causes earthquakes.

     Earthquakes under the ocean depths can cause massive Tsunamis.  Tsunamis also can be created from landslides, volcanic eruptions, asteroids and even comets. Since no one has witnessed that a comet or an asteroid has actually triggered a Tsunami, scientists have used computers to help simulate this occurrence.  When an earthquake under water is large enough is causes a large ripple effect in the water.  This water can cause large devastation to low coastal areas.  When a Tsunami is in route they are hard to see in the open water only looking like a wave.  As the land becomes shallow the wave will become much larger taking shape and crashing into low coastal land.  As of lately the subduction zones off Indonesia area have been hit by large Tsunamis causing wide spread death and destruction.  

     The natural forces above the land help slowly form and change our planet earth over time.  Temperatures over long period of time can create glaciers.  Glaciers are large ice, which flow down hill.  Over time they can help carve out the earth.  During the last ice age glaciers formed over most of the northern hemisphere.   Glaciers from the last ice age help create valleys, mountains and hills and example of this is Yosemite National Park. 

     Ocean water helps shape the earth with the currents affecting our earth’s climate, shorelines and weather conditions.  Hurricanes created over warm water move to land and create massive destruction altering shorelines.  Waves and wind are currently eroding the shorelines of Massachusetts at a loss of .56 feet per year.

     In closing the incredible forces of our restless earth are slowly changing the surface daily.  Over millions of years something as simple as wind can erode a mountain down to a hill.  There are mountains growing larger, some oceans expanding others are shrinking.  As continents grow further apart new oceans may be created and New Mountains formed.  In 100 millions years from now to look at this planet could be exciting bringing a whole new world to those who see it.