Download Layers of the Earth

Layers of the Earth
Inner Core
The inner part of the earth is the core. This part of the earth is about 1,800 miles (2,900 km)
below the earth's surface. The core is a dense ball of the elements iron and nickel. It is divided
into two layers, the inner core and the outer core.
The inner core - the center of earth - is solid and about 780 miles (1,250 km ) thick. The inner
core pressures are so great that it cannot melt, even though temperatures there reach 6700ºF
(3700ºC).
It is 3,200 - 3,960 miles (5,150-6,370 km) below the earth's surface and mainly consists of iron,
nickel and some lighter elements (probably sulphur, carbon, oxygen, silicon and potassium. The
temperature in the inner core is about 9,032 – 10,832 ºF (5000-6000 ºC). Because of the high
pressure, the core is solid.
Outer Core
The inner part of the earth is the core. This part of the earth is about 1,800 miles (2,900 km)
below the earth's surface. The core is a dense ball of the elements iron and nickel. It is divided
into two layers, the inner core and the outer core.
The outer core is so hot that the metal is always molten. The outer core is about 1,370 miles
(2,200 km) thick. Because the earth rotates, the outer core spins around the inner core and that
causes the earth's magnetism.
The outer core is at 1,800 - 3,200 miles (2,890-5,150 km) below the earth's surface. The outer
core is liquid and mainly consists of iron, some nickel and about 10% sulphur and oxygen. The
temperature in the outer core is about 7200 - 9032 ºF (4000-5000ºC).
Mantle
The layer above the core is the mantle. It begins about 6 miles (10 km) below the oceanic crust
and about 19 miles (30 km) below the continental crust. The function of the mantle is to separate
the inner mantle and the outer mantle. It is about 1,800 miles (2,900 km) thick and makes up
nearly 80 percent of the Earth's total volume.
Because the earth is very hot inside, a current of heat flows from the core to the crust. The
average temperature in the inner mantle is 5400 ºF (3000ºC), nevertheless the rock is solid
because of the high pressures. The temperature in the outer mantle is between 2520 ºF (1400ºC)
and 5400 º F (3000ºC), and the material is stiffer because it is not as hot.
Aesthenosphere (uh-sthee-no-sfeer)
The asthenosphere is the layer of Earth that lies at a depth 100–250 km beneath Earth's surface.
The asthenosphere gets its name from the Greek word for weak, asthenis, because of the
relatively fragile nature of the materials of which it is made. It lies in the upper portion of Earth's
structure traditionally known as the mantle.
The material of which the asthenosphere is composed can be described as plastic-like, with much
less rigidity than the lithosphere above it. This property is caused by the interaction of
temperature and pressure on asthenospheric materials.
The temperature of the materials that make up the asthenosphere tend to be just below their
melting point. This gives them a plastic-like quality that can be compared to glass. As the
temperature of the material increases or as the pressure exerted on the material increases, the
material tends to deform and flow.
According to plate tectonic theory, the lithosphere consists of a relatively small number of very
large slabs of rocky material. These plates tend to be about 60 mi (100 km) thick and many
thousands of miles wide. They are thought to be very rigid themselves but capable of flowing
back and forth on top of the asthenosphere.
Crust
The Earth’s crust covers the mantle and is the earth's hard outer shell, the surface on which we
are living. Compared to the other layers the crust is much thinner. It floats upon the softer, denser
mantle. The crust is made up of solid material but this material is not the same everywhere.
There is an Oceanic crust and a Continental crust. The first one is about 4-7 miles (6-11 km)
thick and mainly consists of heavy rocks, like basalt. The Continental crust is thicker than the
Oceanic crust, about 19 miles(30 km) thick. It is mainly made up of light material like granite.
The earth's crust is the thickest below the continents, with an average of about 20 to 25 miles (30
to 40 km) and with a maximum of 45 miles (70 km). The continental crust is older than the
oceanic crust, some rocks are 3.8 billion years old.
The crust itself has no influence on the earth, but the constant moving of the crust does. This
moving is caused by the influence of the convection current, or to be more precise, this
convection current actually causes the earth plates to move and sometimes touch each other.
These movements cause earthquakes and at weak parts of the earth's crust volcanoes can erupt.
Lithosphere (lith-o-sfeer)
The lithosphere is the upper, rigid layer of the Earth. It consists of the crust and the top of the
mantle. It is about 100 km thick. In other words, the lithosphere is made up of solid rock, which
is the Earth’s outer surface, and magma, the hot liquid center of the Earth. Lithosphere means
“ball of stone”.
The lithosphere is broken into 20 or so slabs, called tectonic plates. The continents sit on top of
these plates. Temperatures increase by 35°C for every 1000 m you move down through the
lithosphere.
The boundary between the lithosphere and the asthenosphere occurs at the point where
temperatures climb above 1300°C.
The lithosphere is only a few kilometers thick under the middle of the oceans. Here, the mantle’s
temperature just below the surface is 1300°C.
The lithosphere is thickest — 120 km or so — under the continents.