alrite, the people who do not get earth science that are running around sayin omg its the end of the world or that mother nature has gone mad, READ
THIS! it may take me a couple posts. . .
ok, to start it off: What are plate tectonics????
plate tectonics is the the thery that the Earth's crust, the solid part of the surface, is broken into pieces that "float" on top of a weak,
putty-like layer of the mantle called the asthenosphere (as-TEN-oh-sfeer), meaning "weak sphere."
What are the pieces?
there are a seven main plates:
North American plate
South American plate
and Eurasian plate
and minor plates:
Juan de Fulca plate
and the Philippine Sea plate.
How do they move???
The plates ride atop the asthenosphere. The mantle is constantly going through convection, a process where the heated material rises, because it is
less dense, to the top of the mantle. the colder, more dense material then sinks back to the bottom. the plates in turn ride on these convection
currents. they move very slowly.
But wait, how do we have an idea of this?
look at a map of the world. look at the sides of Africa and South America. do they not look like they fit together? that is called the jigsaw puzzle
theory, which states that all the continents fit together like jigsaw puzzle pieces. this in turn led to the idea of Pangaea, the supercontinent whose
name meant "all land."
also, many continents have things that also fit into this idea. in Texas, there are salt beds that today form only in tropical areas. in some areas,
there are geographical features that stop on one continent and contine on another, like old river beds, mountain chains, striations etc. there can be
fossils where they find the body on one continent and the head on another!
now some of you are probably wondering: But wait, what you said about Africa and South America, if they moved apart like that, how'd they move???
now onto another type of proof we have about plate tectonics becauze it is still happening.
there was a big scientific ship that was sent out to gather rocks from the seafloor of the Atlantic to see how old the Earth was. At that time,
scientists believed that the ocean floor was made of rock unaltered since the formation of the Earth. Now, imagine their surprise when the findings
proved to be less than a few thousand years old! As they neared the center of the Atlantic, the rocks got younger and younger, even a few days old!
this led to the discovery of the Mid-Atlantic Ridge, a submarine mountain chain longer than the Andes. they are so long because they wind more than
the stitches on a baseball. on each side of these mountains is a volcanic ridge that is spewing forth new material every day, causing these continents
to move apart. such a boundary of plates is called divergent because they move apart. if earthquakes occur at these boundaries they are usually weak,
there are two main types, divergent, which i already talked about, and the convergent. Convergent boundaries occur at areas where two plates converge
(big surprise, eh?
) now, if 2 oceanic plates were to converge, they would both go into the mantle, "stoking the fire." where 2 oceanic plates
meet, it is called a trench, a famous one is called the Mariana Trench.
where a continental and an oceanic plate were to meet, the denser oceanic plate would go beneath the continental and push it back, forming mountains.
Volcanoes are also common around these types of boundaries, like the Pacific Ring of Fire.
if two continental plates were to collide, they would both push up, forming mountains. an example would be the Indian-Australian plate and the
Eurasian plate forming the Himalayas.
But what do these have to do with ATS????
Earthquakes, like the ones in Chile, Haiti, China, etc, are a part of this. the reason these ones were so powerful is of the elastic rebound theory.
In this theory, rocks can be elastic, taking some of the pressure from the plates moving. they can only stretch so far, however, without returning to
their original state. the longer you go without a quake, the more powerful the next one will be. make sense? Mother Earth is not going crazy, just
being her usual DYNAMIC self.
volcanoes, like in Iceland (an island which is very volcanically active, btw, which heats its homes using geothermal energy), are also powered by
this. pressure builds up in the mantle and is released through openings in the crust aka VOLCANOES!!!!
But wait, Hawai'i has volcanoes, and they are quiet, why is Iceland so violent???
Now lets look at the chemistry of volcanoes. The ones in Hawai'i are shield volcanoes, which are not powerful. Iceland's is more than likely a
cinder cone, which are explosive.
But shape alone does not contribute to explosivity. Two other components are water and silica. Silica is a mineral that does not melt easily, so it
clogs the volcano in a sense. and when you add a high level of silica to a high level of water, which forms steam, you get a very explosive eruption,
Therefore, volcanoes and earthquakes do not have anything to do with global warming.
i posted only the relevant info. as time goes on, i may just put in a lecture lol. . . if you read this far, thank you, hoped you learned something,
and i appreciate it.
The Public school system is not a loss.
[edit on 16-4-2010 by LocoHombre]