Chapter 1: Section 1
Earth’s Interior
The Science of Geology, pg. 17
• Geologists are scientists who study the
forces that make and shape planet
Earth.
The Science of Geology, pg. 17
• Geology is the study of planet Earth and
the rocks found on the surface.
The Science of Geology, pg. 17
• Geologists:
– Study chemical and physical characteristics of
rock: material that forms Earth’s hard
surfaces.
– Map where different types of rock are found
on and beneath the Earth’s surface.
– Describe landforms (features formed in rock
and soil by water, wind and waves).
– Search for clues about Earth’s history by
studying processes that create Earth’s
features.
Studying Surface Change
• Forces beneath the Earth’s surface
constantly change Earth’s appearance.
• 2 forces that change the surface are:
– Constructive Forces
– Destructive Forces
Studying Surface Change
• Constructive Forces: Forces that shape
the surface by building up mountains
and landmasses (such as islands and
continents).
Studying Surface Change
• Destructive Forces: Forces that slowly
wear away mountains and other features
on the surface (Example: When ocean
waves wear away the shoreline).
?????????????????
• How old is Earth?
• How has Earth’s surface changed over
time?
• Why are there oceans, and how did they
form?
• What’s INSIDE Earth?
Finding Indirect Evidence, pg. 18
• Since geologists cannot dig a hole to the
center of the Earth and make direct
observations (because of extreme
temperature conditions) they rely on
indirect methods of observations.
• FYI: The deepest level reached was at a
gold mine in South Africa (Depth of 3.8km)
You would need to travel 1,600 times that
depth to reach the center of the Earth, or
approximately 6,000km.
Finding Indirect Evidence, pg. 18
• Geologists use Seismic Waves: A
vibration that travels through Earth
carrying the energy released during an
earthquake.
• They record the waves and study how
they travel through Earth (speed, paths
taken).
Finding Indirect Evidence, pg. 18
• These indirect observations allowed
scientists to learn about the Earth’s
interior:
– It is made up of several layers.
– Each layer surrounds the layers beneath it
(Similar to an onion).
A Journey to the Center of the
Earth, pg. 19
• To get to the center of the Earth, you
will travel through several different
layers.
• The 3 main layers of the Earth’s
Interior are:
1. Crust
2. Mantle
3. Core
• Each is made up of its own materials and has its
own conditions.
A Journey to the Center of the
Earth, pg. 19
• Temperature:
– On the surface of the Earth, the rocks are
cool
– As you reach about 20m below they become
warmer. Every 40m from this point, the
temperature rises 1oC for several km then
continues to increase slow and steady
A Journey to the Center of the
Earth, pg. 19
• Pressure is the force pushing on a surface or
area.
– As you travel further below the Earth’s
surface, the pressure increases.
The Crust, pg. 20
• The Crust is the layer of rock that forms
Earth’s outer skin.
• This is where we find rocks, mountains, soil
and water. It includes the dry land as well as
the ocean floor.
The Crust, pg. 20
Basalt
• The crust is the thinnest beneath the ocean
and the thickest under mountains.
• Thickness averages at 32 kilometers thick.
• The crust beneath the ocean is called oceanic
crust which has very dense rocks such as
basalt; a dark dense rock with a fine texture.
The Crust, pg. 20
• The crust that forms the continents is called
continental crust which is made up of less
dense rocks such as granite; a light colored,
less dense rock.
Granite
The Mantle
• As you move beneath the crust you will reach
the Mantle made up of a layer of hot rock.
• Thickness is 2,900 kilometers and goes almost
halfway to the center of the Earth.
• As you move towards the Earth’s center, the
mantle is hotter and under increasing
pressure.
• The mantle is soft, like tar and can bend, like
plastic and can flow easily.
The Mantle
• The upper part of the mantle AND the crust
together form the lithosphere, meaning
“stone.” It is solid and rigid.
• Below the lithosphere, where you encounter
the soft and bendable layer of the mantle, it
is called the asthenosphere, meaning “weak.”
The Core, pg. 21
• 2 parts of the core:
• Outer Core
• Inner Core
• Combined they make up 1/3 of the Earth’s mass.
But only 15% of its volume.
• Together they are slightly smaller than the moon.
• Temperature ranges from 2,0000C to 5,0000C,
about the temperature of the sun’s surface.
The Core
• Outer Core:
•
•
•
•
Surrounds the inner core.
Layer of molten metal.
Thick liquid
A lot of pressure!
The Core
• Inner Core:
• Dense ball of solid metal.
• Extreme pressure squeezed atoms of iron and
nickel so much that they cannot spread out to
become a liquid.
Earth’s Magnetic Field, pg. 24
• Currents in the liquid outer core force the
solid inner core to spin slightly faster than
the rest of the planet.
• The currents in the outer core creates
Earth’s magnetic field, causing the planet to
act as a giant magnet.