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Transcript
Earth Systems
The Earth’s resources were determined
when the planet formed.
• Earth is ~4.6 Billion years old
• Almost all of the elements
currently found on the planet
were present during formation.
• As the forming Earth cooled,
heavier elements condensed due
to gravity and settled based on
mass.
• Ex. Iron sank towards the center
and silica settled towards the
surface.
• Gaseous elements became the
atmosphere
The Earth’s Layers
• This settling by mass
resulted in distinct
vertical layers
• Core - the innermost
zone of the planet
made of nickel and
iron.
• Mantle - above the
core containing
magma
• Crust - the outermost
layer of the planet.
The Earth’s Layers
• Asthenospherethe outer part of
the mantle,
composed of semimolten rock.
• Lithosphere- the
brittle outermost
layer of the planet
Lithosphere
• Made up of several large plates and numerous small plates
• Includes the upper mantle and crust
• Contains soil on the upper crust which is what allows life on
the planet to exist because they contain the elements
required for life
Earth is dynamic and constantly
changing
• Earth’s geologic cycle consists of 3
major processes:
1. Tectonic Cycle
2. Rock Cycle
3. Soil formation
Convection and Hot Spots
• Despite being 4.6 byo, the planet remains very hot at
its center
• The heat causes hot magma plumes to well upward from the
mantle producing hot spots
• Hot Spots: places where molten material from the mantle
reaches the lithosphere
Theory of Plate Tectonics
• States that the Earth’s lithosphere is divided into plates, most
of which are constantly in motion
• Tectonic Cycle – The sum of the processes that build up and
break down the lithosphere
Plate Tectonics
• The lithosphere is broken into plates:
• Oceanic Plates: Lie primarily beneath oceans
• Crust is dense and rich in iron
• Continental Plates: Lie beneath land masses
• less dense and has more silicon dioxide
Continental plates are lighter and will rise above oceanic plates
Plate Tectonics
• Convection: the movement of hotter and less dense material
to rise, and colder, denser material to sink which results in the
transfer of heat.
• Where oceanic and continental plates come together,
subduction occurs
• Subduction: Plates passing under one another
Consequences of Plate Movement
• As a plate moves over a geologic hot spot, heat from the
rising mantle plume melts the crust and forms a volcano
• Volcano: a vent in the Earth’s surface that emits ash, gases,
and molten lava.
Plate movement over a hot spot
• Hawaiian islands are an
example of how land
can form over hot spots
due to volcanic
eruption
• Geologically, this is how
all land originally
formed
• The eruption and
cooling of molten lava
Types of Plate Contact
• Divergent plate
boundaries- when plates
move apart from one
another.
• Convergent plate
boundaries- when plates
move toward one another
and collide.
• Transform fault
boundaries- then plates
move sideways past each
other.
Divergent Boundaries
• Occur between oceanic plates
• Plates move away from each other, new magma rises
and cools to form new lithosphere
• This is called seafloor spreading
Convergent Boundaries
• If oceanic collide with continental, a coastal mountain range
will form because the lighter continental plate will rise on top
of the heavier oceanic plate which will subduct
• If 2 continental plates collide, both margins will rise forming a
mid-continental mountain range
Transform Fault Boundaries
• Transform boundaries are where plates slide against each
other
• Faults- a fracture in rock across which there is movement.
• Earthquakes- occur when the rocks of the lithosphere rupture
unexpectedly along a fault.
The Rock Cycle
• Rock cyclethe constant
formation
and
destruction
of rock.
The Rock Cycle
• Igneous rocks- rocks that form directly from
magma.
• Sedimentary rocks- form when sediment such
as mud, sands, or gravels are compressed by
overlying sediments.
• Metamorphic rocks- form when sedimentary,
igneous or other metamorphic rocks are
subjected to high temperatures and
pressures.
Weathering and Erosion
Weathering- when rocks are exposed to air,
water, certain chemicals or biological agents
that degrade the rock.
Weathering and Erosion
• Physical weathering- the mechanical
breakdown of rocks and minerals.
• Chemical weathering- the
breakdown of rocks and minerals by
chemical reactions.
Erosion
• Erosion- the physical removal of rock
fragments from a landscape or ecosystem.
Wind, water, ice transport and living
organisms can erode materials.
• Deposition- the accumulation or depositing of
eroded material such as sediment, rock
fragments or soil.
Soil
• Soil is important
because it
• Is a medium for
plant growth
• Serves as a filter for
water
• A habitat for living
organisms
• Serves as a filter for
pollutants
The Formation of Soil
• Factors that determine the formation of soil:
• Parent material- what the soil is made of
influences soil formation
• Climate- what type of climate influences
soil formation
• Topography- the surface and slope can
influence soil formation
• Organisms- plants and animals can have
an effect on soil formation
• Time- the amount of time a soil has spent
developing can determine soil properties.
The Formation of Soil
• Parent Material- the rock material
from which soil is derived.
Soil Horizons
• As soils form, they develop
characteristics layers.
Soil Horizons
• O horizon- (organic layer) composed of the
leaves, needles, twigs and animal bodies on
the surface.
• A horizon- (topsoil) the zone of organic
material and minerals mixed together.
• B horizon- (subsoil) composed primarily of
mineral material with very little organic
matter
• C horizon- (parent material) the least
weathered horizon and is similar to the
parent material.
Physical Properties of Soil
• Texture- the percentage of sand, silt
and clay the soil contains.
Physical Properties of Soil
• Porosity- how quickly the soil drains
(which depends on its texture)