Transcript EARTH SCIENCE - Regional School District 17

EARTH SCIENCE
A Quick Review
Where are we?
• 3rd planet from the sun
• About 92 million miles
– Perfect distance to balance warmth
– “The Water Planet”
Who are we?
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Geosphere
Hydrosphere
Atmosphere
Biosphere
Earth’s History
• About 4.6 billion years old (according to rock record)
• Geologic Time scale - broken down into eons, eras, periods
and epochs. (Precambrian epoch = 87% of time scale)
Earth’s History
• Divisions mainly dependent on rise of certain
types of organisms or major events.
Earth’s Composition
• 3 major concentric zones
• Core:
– Solid inner – due to
pressure (Ni & Fe)
– Molten outer - creates
magnetic field (Fe & S)
• Mantle:
– Mostly solid
– Asthenosphere = slowly
flowing
• Lithosphere:
– Thin rigid
– Contains the crust
Earth’s Magnetic Field
Earth’s Crust
• Oceanic crust – mostly basalt (more dense, ~3.0g/cm3)
• Continental crust – mostly granite (less dense, ~2.7g/cm3)
Plate Tectonics
• Nuclear decay in the
core releases heat into
the mantle and
asthenosphere causing
convection currents that
create plate movement
Plate Tectonics
• Convection currents have
caused the mass movement of
plates over millions of years.
Plate Tectonics
• The movement of these plates is
called “Continental Drift”.
Plate Tectonics
• Each individual plate (about 12)
is made of lithosphere and
mantle.
Plate Tectonics
• Today, the plates are still in
motion –
– PLATE TECTONICS
– http://sos.noaa.gov/videos/Paleo3.mov
Plate Tectonics
• The plates today:
Plate tectonics
• Plate boundaries – edges of the plates
– Three types: convergent, divergent and
transform
Earth’s Crust
• Convergence
(subduction)
• Creates mountains and volcanoes
Earth’s Crust
• Divergence (ridge formation)
– Creates volcanoes and new crust
Earth’s Crust
• Transform –
plates sliding
past one
another.
– Creates
earthquakes
Volcanoes
• Active
• Dormant
• Extinct
• Subduction volcanoes
– At plate boundaries
• Hot spot volcanoes
– In the middle of plates
Volcanoes
• Rift Volcanoes
– Form new oceanic crust
Earthquakes
• Each black
dot is the
location of
an
earthquake
Earthquakes
• Anatomy:
– Fault
– Focus
– Epicenter
– Waves
Rock Cycle
• Rocks come from rocks
• Time, erosion, pressure and heat create 3
basic types
– Igneous
– Sedimentary
– Metamorphic
• Erosion
Rock Cycle
Soil
• A crucial link between
biotic (living) and abiotic
(nonliving)
Earth’s orbit and rotation
• Revolution, rotation and tilt determine our
days and seasons.
Seasons
• Spring in the Northern, Autumn in the
Southern
Seasons
• Summer in the Northern, Winter in the
Southern
Seasons
• Autumn in the Northern, Spring in the
Southern
Seasons
• Winter in the Northern, Summer in the
Southern
The Atmosphere
• A layer of gases held
close to the Earth by
gravity
• With the help of the
sun, it’s where our
weather and climates
occur
Atmosphere
• Troposphere – all of
the weather, most of the
water vapor and clouds.
• Well mixed layer.
• Area of the atmosphere
that holds the
greenhouse gases
The Greenhouse Effect
• Without the
greenhouse
gases (CO2,
H2O, and
CH4) in the
atmosphere,
we wouldn’t
survive.
Atmosphere
• Stratosphere – not well
mixed.
• Contains the ozone
layer (O3)
Atmosphere
• Mesosphere – where
meteors usually burn
up.
Atmosphere
• Thermosphere
(or Ionosphere)
• Thinnest gas
layer
– Aurora’s
– Space shuttles
– Ionization
(absorption of
solar wind)
– Reflects radio
waves
Atmosphere
• Exosphere
– Satellites
– Lightest gases –
H2 and He
Atmosphere
• Magnetosphere – area where the magnetic field of
the earth dominantly controls the movements of gas
and charged particles.
Hydrosphere & Biosphere
• We’ll cover these later…..