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Crust
The Earth consists of four main parts, the inner core, outer core, mantle and the
crust. The crust is Earth’s most external layer out of all the four layers mentioned. The
crust consists of two parts the oceanic and continental crust. These crusts hover above the
earth’s mantle, which is basically a river of molten rocks that is 2850 km thick. This outer
most “coating” is more emaciated when compared to the other layers.
If you were to look at the whole world through a satellite screening you would be
able to tell that the majority of the earth is covered by a great deal of water. Below these
large masses lies one of the two types of crust, the oceanic crust. This crust is
approximately 4-7 miles thick. When compared to the continental crust, this crust is
much younger. The oceanic crust has its own type of rocks, known as tholeiitic basalt.
Theoliitic basalt has a very dark, gritty, and fine volcanic structure formed from much
liquefied lava. The grains of this rock are so small you must operate a microscope to be
able to have a clear observation of the material. This crust on average has a density of
3g/cm3
We by now know that the earth is mostly covered with oceanic crust; the other
small percent is land. “Land” as we refer to it was actually a gargantuan ground mass
way back, known as Pangaea. As the years passed on, movements of the earths crust
began to break down the “super continent”, which eventually led to the creation of 6 large
masses of land other wise known as continents. These continents are part of the
continental crust. The six continents are Eurasia, Africa, North America, South America,
Antarctica, and Australia. Scientist hasn’t really identified the thickness of this crust but
they say on hypothesis that below the continents is approximately 26-40 miles max. This
crust is much older than the oceanic crust, mentioned above reaching to ages of about 8
billion years old. The continental crust consist of two layers the upper and lower magma.
Both layers produce rather igneous rocks, the upper produces granite. Granite has light
coloration and is a coarse grain of magma. The lower part produces diorite, which share
same compositional make ups with granite, but is scarcer, which is formed by impurities
within the magma. On average the density of the continental crust is 7g/cm3
The crust itself does not affect or influence the earth however; the movements of
these do leave a mark. The movements of plates are caused by convection currents. These
measurable movements cause minor or dramatic earthquakes, which delivers regrettable
results. Some times at the weak points volcanoes have the capability of erupting. Due to
all these movements of the earth’s crust we now have valleys and mountains.