Transcript The Inner Earth

The Inner Earth
http://www.mnh.si.edu/earth/text/4_1_4_0.html
The Earth’s Layers
 The inner Earth is layered.
Beneath its familiar surface
and thin crust lie a rocky
mantle and iron core.
The inner Earth is hot. Its
core is hotter than the
surface of the Sun. The
escape of this inner heat to
cold outer space causes the
tectonic plates to move. The
inner Earth flows and
churns. In the mantle,
flowing rocks help move the
plates above them. In the
outer core, a churning
dynamo of liquid iron
generates Earth's magnetic
field.
 During Earth’s first 100 million
years, ever-larger particles in
the infant Solar System
collided and stuck together —
generating tremendous heat.
 Earth expanded, then melted
completely, and layers began
to form.
 Dense molten iron sank and
created the core.
 Lighter silicate liquid rose
and cooled, forming the
mantle.
 Later, partial melting of the
mantle produced the crust
— a process that continues
today.
The Crust- Earth’s Thin Skin
 Relative to its size,
Earth's crust is about as
thin as an apple's skin.
This outermost layer is
composed primarily of
two types of rock.
 Granite
The continental crust is
mostly granite.
 Basalt
The oceanic crust is
mostly basalt.
The Mantle- Deep and Dense
 About 84 percent of
Earth's volume is mantle
rock.
 The uppermost 100km of
the mantle is rigid. This
upper mantle with the
crust makes up
the lithosphere (the
plates).
 The next layer, the
asthenosphere, is solid,
hot, and soft. It flows
much like a glacier does.
 The lower mantle is
extremely dense. It, too,
flows.
The Core – Iron Center
 About 15 percent of
Earth's volume is a
molten iron-nickel core.
 The outer core is molten
and is the size of Mars. It
is so hot it could be as
fluid as water. Its
motions create Earth's
dynamic magnetic field.
 The inner core is under
such immense pressure
that it is solid metal.