Earths Changing Surface Earth is a constantly changing body affected by natural forces On the Inside Plate Tectonics moving of Earths Plates driven by convection currents Earthquakes amp Volcanoes ID: 515028
Download Presentation The PPT/PDF document "Weathering & Erosion" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Weathering & ErosionSlide2
Earth’s Changing Surface
Earth is a constantly changing body affected by
natural forces
:
On the
Inside
:
Plate Tectonics
= moving of Earth’s Plates driven by
convection currents
Earthquakes & Volcanoes
On the
Outside
:
Weathering
&
ErosionSlide3
Weathering & Erosion
Weathering
is the process of
breaking down
or
dissolving
the earth’s rocks.
Mechanical
Weathering
Chemical
Weathering
Erosion
is the process of
moving
particles of rock from one locations to another.
Water
Glaciers
Wind
No rock is heard enough to resist the forces of weathering and erosion. Together they shape Earth’s
topography
.Slide4
Weathering
The interaction of the
lithosphere
(rock) with
the
atmosphere
(air) and
hydrosphere
(water) results
in
weathering
.
Driven by
climate
, combination of temperature and precipitation.
Hot & humid
=
greater
amount of weathering
Cool & Dry
=
reduced
amounts of weatheringSlide5
Physical Weathering
The type of weathering in which rock is
slowly
,
mechanically
broken down into
smaller
pieces.Changes the size and shape of the rock but not is composition
.
Factors:
Freezing and Thawing
Plant & Animal Actions
AbrasionsSlide6
Freezing and Thawing
In
colder
climates, water seeps into cracks and freezes.
The freezing water
expands
, making the crack
bigger – frost action.Slide7
Growth of Plants
As plants grow, their roots move into the cracks of rocks.
As roots grow, cracks become larger.
Roots grow into
c
racks and make
t
hem bigger.Slide8
Animal Actions
As animals
dig burrows
in the ground they loosen and break apart rocks in the soil.Slide9
Abrasion
Wind
,
water
and
ice
carry smaller sand and rock particles that act like
sandpaper on other rock surfaces.
Glacial Abrasion
Wind AbrasionSlide10
Chemical Weathering
The process of weathering that changes the rock’s
size
,
shape
AND
composition
.Produces rock particles that have a different mineral makeup from the rock that it came from.Agents:
Water
Oxygen
Carbon dioxide
Acid rainSlide11
Water
The
universal solvent
that dissolves substances,
solutes
, into solution.
As a rock is covered by water, minerals leave the rock by dissolving out.
Creates spaces in the rock that can weaken it and cause it to break apart.Slide12
Oxygen
Oxygen reacts easily with other substances changing their properties.
Oxygen (O) + Iron (Fe) = Iron oxide (Fe
2
O
3
), rustSlide13
Carbon Dioxide
Does not contribute to chemical weathering until dissolved in water.
Water (H
2
O) + Carbon Dioxide (CO
2
) = (H
2CO3) carbonic acid
Carbonic acid dissolves
calcite
,
f
ound in l
imestone
. Causes caves
a
nd caverns; Howe CavernsSlide14
Acid Rain
Acid rain comes mostly from the
burning of coal
by power plants in the Midwest.
Sulfur oxides rise into the air combining with water to form sulfuric acid.
Lowers the pH of water and bedrock killing off living organisms.
pH of lemon juiceSlide15Slide16
Soil Formation
The formation of soil is a
slow and complex
process through the processes of
weathering
mixing with
organic matter
. Can be hundreds to thousands of years, 200-1200 years, in hard rock areas.Can takes less time, 20 years, in softer bedrock areas of shale and sandstone.Slide17
Soil Formation
Unweathered
Rock
Partially weathered
Rock
Partially weathered
Rock
Unweathered
Rock
Partially
weathered
Rock
Unweathered
Rock
Top Soil
Top Soil
Subsoil
Immature Soil
Mature SoilSlide18
Soil Horizons
Horizons:
O
Horizon –
organic material
Decayed plants and animals,
humus
A
Horizon –
topsoil
Humus, clay and minerals
B
Horizon –
subsoil
Clay but little humus
C
Horizon –
bedrock
Partly weathered rockSlide19
Soil Composition
Soil
– a mixture of rock particles (sand, silt and clay), minerals, decayed organic material (humus), air and water formed from
weathered rock
.Slide20
Soil Texture
Soil texture depends on the size of individual soil particles that make it up.
Gravel
– 2mm and larger
Sand
– less than 2mm
Silt
– less than 1/16mmClay - less than 1/256mmSlide21
Erosion
The
movement
of rock particles
from
one location to another,
Erosion
, in a downhill motion toward their lowest possible location; sea level.Agents of Erosion:
Water
Glaciers
WindSlide22
Erosion by Water
Water is always moving
downhill
due to the force of
gravity
.
The
greatest force of erosion.Wears down mountains to hillsCarves out valleysChanges the direction of river flow.Slide23
Erosion by Glaciers
Glaciers are formed from accumulated
snow
, compacted into
ice
and being pulled downhill by the force of
gravity
.Begin to form when snow reaches approximately 150ft in depth.Act as bulldozer
,
moving large amounts of rock and soil over time,
till
.
Material deposited after a glacier stops moving,
moraine
.Slide24Slide25
Erosion by Wind
A major force of
physical
weathering, wind is also a contributor to
erosion
.
Creates
and transports rock particles.