Transcript layers of the Earth are the crust

Inside the Earth
The Layers of the Earth
© Copyright 2006. M. J. Krech. All rights reserved.
The Three Main Layers
The three main
layers of the Earth
are the crust, the
mantle, and the
core. These layers
vary greatly in
size, composition,
temperature, and
pressure.
The Crust
• The crust is the layer that forms the
outer “skin” of the earth
• It is a layer of solid rock that includes
both dry land and the ocean floor.
• It is the thinnest layer of the earth and
is between 5-100 km thick.
• It is thickest under mountains and
thinnest beneath the ocean.
• 2 types of crust
– Oceanic (very dense, made of basalt)
– Continental (less dense, made of granite)
Oceanic and Continental
Crust
The Crust
The crust of the Earth is broken into many
pieces called plates. The plates "float" on
the soft, semi-rigid asthenosphere.
The Mantle
• The mantle is the layer of
the earth between the crust
and core.
• The mantle is made up of
rock that is very hot, but
solid.
• Scientists further divide the
mantle into layer based on
physical characteristics of
those layers: lithosphere,
asthenosphere, and lower
mantle.
The Mantle’s Lithosphere
The crust and the upper layer of the
mantle together make up a zone of rigid,
brittle rock called the Lithosphere. In
Greek, litho means “stone”.
The Mantle’s Asthenosphere
• The middle layer of the mantle is hotter and
under increasing pressure. The asthenosphere
is a softer layer than the rigid lithosphere, but
is still considered to be solid.
• It is soft enough
to bend like
plastic, but hard
enough to stub
your toe if you
kicked it.
Convection Currents in the
Mantle
The middle mantle
"flows" because of
convection currents.
Convection currents are
caused by the very hot
material at the deepest
part of the mantle rising,
then cooling and sinking
again --repeating this
cycle over and over.
The Core
• At Earth’s center you will find the core which
is broken into two parts- the outer core and
the inner core.
• The core (both the outer and inner) makes
up Earth’s thickest layer
The Outer Core
• The Outer Core is a layer
of molten metal (iron
and nickel) that
surrounds the inner core.
• The outer core is liquid
and scientist believe that
the movements in the
liquid outer core create
Earth’s magnetic field.
The Inner Core
• The Inner core is a
dense ball of solid
metal.
• The core of the earth
makes up about 33% of
Earth’s mass
• Temperatures in the
inner core ranges up to
5,000 degrees Celsius.