Big Idea 6:
Earth Structures
Description
Over geologic time, internal and external sources of energy have continuously altered the features
of Earth by means of both constructive and destructive forces. All life, including human civilization,
is dependent on Earth's internal and external energy and
material resources.
Benchmark Number & Descriptor
• SC.6.E.6.1
• Describe and give examples of ways in which
Earth's surface is built up and torn down by
physical and chemical weathering, erosion, and
deposition.
• SC.6.E.6.2
• Recognize that there are a variety of different
landforms on Earth's surface such as coastlines,
dunes, rivers, mountains, glaciers, deltas, and
lakes and relate these landforms as they apply
to Florida.
WEATHERING
• Weathering - processes at or near Earth’s
surface that cause rocks and minerals to
break down
Salt weathering of sandstone near
Qobustan, Azerbaijan.
PHYSICAL WEATHERING
• Process by which rocks
are broken into smaller
pieces by external
conditions.
• Types of physical
weathering
– Frost heaving and Frost
wedging
– Plant roots
– Friction and impact
– Burrowing of animals
– Temperature changes
CHEMICAL WEATHERING
• The process that
breaks rock through
chemical changes
• The agents of
chemical weathering
–
–
–
–
–
Water
Oxygen
Carbon dioxide
Living organisms
Acid rain
EXAMPLES of WEATHERING
EXAMPLES of WEATHERING
Ice causes weathering
EROSION
• Process by which
weathered rock
and soil
(sediment) are
moved from one
place to another
• Erosion gradually
wears down the
surface of the
Earth.
• Erosion carves
the Earth's
surface creating
canyons, gorges,
and even
beaches.
Types of Erosion
• Wave action
• Glaciers
• Running water
• Rock fall
• Landslides
• Mud flow
• Avalanche
• Wind
TYPES of EROSION
WIND EROSION
• As wind blows,
particles of
sand/sediment blast
large rocks. As a result,
these particles cut and
shape the rock.
WATER
• When water flows over
land, erosion occurs.
• When rain falls to the
Earth, it can evaporate,
sink into the ground, or
flow over the land as
runoff.
• Runoff picks up pieces
of rock and "runs"
downhill cutting tiny
grooves.
TYPES of EROSION
ICE
• Glaciers wear down the
landscape.
• Pick up and carry
debris that moves
across the land along
with the ice
GRAVITY
• Gravity pulls down
mass.
• How much erosion
takes place is
determined by the:
• Sum
• Slope
• Speed
• Surface
Deposition
• The process in which sediment is laid
down in new locations
– The end result of erosion
Types of Deposition
Water Deposition
Wind Deposition
• Alluvial fan- fan shaped
deposit of sediment on
land
• Delta- sediment from a
stream deposited where a
river enters a large body
of water
• Sand dunes- large
deposits of sand dropped
from wind
– Sand dunes can move as
the wind picks up sand
from the back of the dune
and blows it to the front.
Types of Deposition
Glacial Deposition
• As a glacier melts, it
creates landforms by
depositing the
sediments it has been
carrying.
– Till-unsorted mixture of
sediment containing
fragments of various
sizes
– Moraine-mounds of
sediment at the downhill
end of the glacier and
along its side
• Long Island is a glacial
moraine.
KNOWLEDGE CHECK
1. What is the difference between
weathering and erosion?
2. Describe 2 types of weathering.
3. Describe 2 types of erosion.
4. What is deposition, and when does it
occur?
KNOWLEDGE CHECK
1.
2.
3.
4.
What is the difference between weathering and erosion?
Weathering is the breaking apart of rocks and minerals;
Erosion is the movement of the pieces caused by weathering.
Describe 2 types of weathering.
Physical – external conditions
Chemical – chemical change
Describe 2 types of erosion.
Wind – blowing particles
Ice – glaciers wearing down land
What is deposition, and when does it occur?
-The process in which sediment is laid down in new locations
-The end result of erosion
LANDFORMS of FLORIDA
FLORIDA’S PAST
• 240 million years
ago:
– Florida was connected
to the Northwest
section of Africa.
• During Pangaea –
Supercontinent
• 200 million years
ago:
– Pangaea broke apart
and the central
Atlantic Ocean was
formed.
BUILDING
FLORIDA
The
Florida
Platform
• Once the supercontinent broke
apart, Florida sank under
shallow water.
• Many marine organisms
thrived in this shallow water.
• Most marine organisms
were made of calcium
carbonate.
• Over time as these organisms
die, the calcium carbonate
turns into limestone.
– Over time the layers of
limestone have built up
creating a solid platform for
Florida.
BUILDING
FLORIDA
EROSION
OF
Appalachian
Mountains
– About 30 million years
ago, the Appalachian
Mountains began to
erode.
– The sediments from
these mountains were
carried south by
currents.
– These sediments
covered the limestone
platform and began to
build Florida’s ground.
– Keep in mind, Florida is
still underwater.
BUILDING
FLORIDA
Ice Ages
– During the Ice Ages,
glaciers melted and
refroze.
– During this time, water
levels rose and fell
depositing sediments in
various locations on the
Florida peninsula.
BUILDING
FLORIDA
An Arch of
Islands
– Key West is an arch of
islands located south of the
southern tip of Florida.
– Corals grew under the
shallow seas. As they died
out, new corals grew, adding
height to this land mass.
– Eventually, the land
surfaced creating the upper
Keys.
– The lower Keys were created
by sand drifts which
covered the coral and
eventually rose to sea level.
KNOWLEDGE CHECK
1. Describe three factors that helped
form Florida.
2. How was the limestone platform of
Florida formed?
3. How are coral and the Florida Keys
related?
KNOWLEDGE CHECK
1. Describe three factors that helped form Florida.
Florida platform, erosion of Appalachian
Mountains, and Ice Age
2. How was the limestone platform of Florida
formed?
These organisms die, the calcium carbonate
turns into limestone.
3. How are coral and the Florida Keys related?
Corals grew under the shallow seas. As
they died out, new corals grew, adding
height to this land mass. Eventually, the
land surfaced creating the upper Keys.