Transcript Chapter 2

Earth as a system
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Chinese (780B.C.)– earthquakes
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Greeks (200B.C.) – minerals
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Mayans (1100B.C.) - astronomy
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Geology
Oceanography
Meteorology
Astronomy
Environmental Science
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Formed about 5
billion years ago.
71% of earth is
covered in ocean.
Not a perfect sphere
because of rotation.
From space height
and depth of
mountains and space
do not appear
significant.
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Seismic activity both manmade and natural
give clues to the composition of earth’s interior.
Three distinct layers
Crust
 Mantle
 Core
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Crust
– thin
– accounts for 1% of the
earth’s mass.
– Moho (Mohorovicic)
the boundary between
crust and mantle layer
just inside of crust.
– 2 types of crust
• Continental
– 15-80km in thickness
– 2.7g/cm3 density
• Oceanic
– 5 to 10km in thickness.
– 3.0 g/cm3 density
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Denser material than
the crust.
Thickness 2900km.
2/3 of the earth’s
mass.
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Center of the earth.
Composed primarily
of iron and nickel.
The iron core is about
7000km in diameter.
The outer portion
being liquid and the
inner portion being
solid.
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1.
Composed of 5
structural zones.
Lithosphere
upper most part of the
mantle and crust.
– Solid and rigid.
– 15 to 300km thick.
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2.
Asthenosphere
middle portion of
mantle.
– Solid but plastic like
(plasticity).
– 200 – 250 km in
thickness.
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3.
4.
5.
Mesosphere – Layer
below Asthenosphere
more rigid is structure.
Outer Core – 2900km
depth start the outer
core believed to be
liquid.
Inner Core – 5,150km
depth starts the inner
core believed to be solid.
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The earth generates a
magnetic field
thought to be caused
by the rotation of the
outer liquid iron
nickel core.
This field is known as
the magnetosphere
and it shields the
earth from cosmic
radiation (solar wind).
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Atmosphere – 78% nitrogen and 21% oxygen.
Upper atmosphere provides UV protection.
Hydrosphere – 71% of earth’s surface. 97% of
water is salt water. The 3% that is fresh is
found in lakes , streams, aquifers and ice.
Geosphere – Rock, soil, continents and oceanic
floor and the molten portion of the earth.
Biosphere – The volume 8km above the earth’s
surface to 8km below the earth’s surface and
organic material.
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Gaia hypothesis – all organic and inorganic
things work together as a system.
Two components of any system are matter and
energy.
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Closed System – energy can enter or exit but matter
does not enter or leave.
Open System – energy and matter can leave or enter
the system.
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All life at one time was
believed to be dependent on
energy from the sun. In the
1970’s it was found that food
webs could also be
dependent on chemicals
ejected through deep
volcanic vents found in the
ocean floor.
Internal energy comes from
radioactive decay and
gravitational contraction.
External energy comes from
the sun.
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Nitrogen cycle – used
in the formation of
proteins.
78% of air is Nitrogen
gas.
Bacteria fix Nitrogen
(make it into a useable
form) for plants and
then animals. NH3 ,
NO3, NO2
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Carbon forms the
backbone for many
organic molecules.
Carbohydrates are a
primary energy
source for many
organisms.
Carbon dioxide can be
fixed by plants into a
useable form.
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Phosphorous does NOT
cycle well.
Phosphorous is trapped in
rocks and as weathering
takes places phosphorous
is released.
It is absorbed by plants
and then consumed by
animals.
Phosphorous is used in
the formation of nucleic
acids.
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Evaporation
Transpiration
Condensation
Precipitation
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Roles
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Consumers
Producers
Decomposers
Carrying Capacity
Foods and Webs
Succession
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Primary
Secondary
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Trophic Levels
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4 to 5 levels tops
More levels at
equator than at poles.
Energy Loss
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Repair
Regulation
Response
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Loss of habitat
Water pollution
Greenhouse effect
Ozone Depletion
Overpopulation
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