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The Dynamic Earth
Chapter 3
Earth as a System
 Geosphere
– land 6,378 km radius
 Atmosphere
– mixture of gases, air
 Hydrosphere
 Biosphere
– water covers 2/3’s
– life exists, 9 km above
to the bottom of the ocean
Earths Interior
 Each
layer of the earth gets denser
the deeper it gets
 Three Compositional Layers:
 1. Crust – outer layer, 5-8km under
the oceans, 20-70km under the
continents
 2. Mantle – 2900km thick, medium
dense 64%
 3. Core – radius of 3400 km, most
dense
The Geosphere
Five Physical Layers of the Earth
 Lithosphere
– cool, rigid layer, up to
300 km, makes up the pieces called the
tectonic plates
 Asthenosphere – plastic, solid layer of
mantle that flows smoothly and the
tectonic plates move on top of it, 250 km
 Mesophere – lower part of the mantle,
2550 km
 Outer Core – made of liquid nickel and
iron, 2200 km
 Inner Core – 1228 km, solid nickel and
iron
Plate Tectonics
 Continents
are on the tectonic plates
and move with them
 Major tectonic plates are the Pacific,
North American, South American,
African, Eurasian and Antarctic
 Geologic activity occurs at the
boundaries between tectonic plates
 Plates collide, pull apart, slip past each
other cause mountains to form,
earthquakes and volcanoes
 Fault
Earthquakes
– break in the crust that is where
earthquakes occur
 Richter scale 2-9.5- measure of the
magnitude of an earthquake, each
number is 31.7 times stronger than
the number below
Volcanoes
Ring of Fire Contains 75% of the worlds
active volcanoes
Located on plate boundaries
Erosion
 Removal
material
 2 Types:
 Water
 Wind
and transport of surface
Erosion – rivers and oceans
Erosion – deserts and beaches
Atmosphere  Mixture
of gases surrounding earth
 Constantly changing
 Insulates thus keeping earth temperature
constant
 Nitrogen makes up 78%
 O, Ar, Co2, methane, water vapor
 Atmospheric Dust-soil, salt, ash from
fires, volcanic ash, pollen, bacteria,
viruses
 Air pressure is less dense the further out
Atmosphere – 4 layers
1.Troposphere – area closest to the
ground, 18 km 75%of the gases, dust,
ice and liquid water-Weather, Clouds, and
smog occur here
 2. Stratosphere – 18-50 km Ozone
layer, temperature rises
 3. Mesosphere – 50-80 km, coldest
layer, down to -92o C
 4. Thermosphere – contains the
ionosphere where electrical charged
particles are (get AM radio at night when
sun goes down, particles quit jumping)
 Temperatures up to 2000oC
 Energy
Transfer occurs by:
 Radiation – electromagnetic waves, no
contact but still feel it, moves from object
with a higher temperature to one with a
lower temperature
 Conduction – direct contact, fast
moving molecules to slow moving
molecules
 Convection – density differences, air is
warmed, the air molecules move apart
which increases the volume of air which
reduces its density thus the air raises and
causes a circular movement of air called
a convection current
Green House Effect
 Solar
energy is trapped next to the
earth’s surface by the atmosphere
 Gases that trap heat next to earth are
called greenhouse gases: water vapor,
carbon dioxide, methane and nitrous
oxide
 These gases keep earth warm enough
to support life as we know it.
Water Cycle
Water on Earth
Hydrosphere – all water on earth’s surface,
covers 70% of earths surface, 97% salt water,
of the remaining 3% - 2/3’s is frozen in the ice
caps of the south and north poles
 Water Cycle – water constantly moves
between the atmosphere and earth, sun
provides the energy for this

– Evaporation - Heat from sun cause water to
evaporate into the atmosphere into water
vapor
– Condensation -Water vapor changes back into a
liquid in the atmosphere as it cools, when it
condenses it forms clouds
– Precipitation – clouds cannot hold any more
water vapor, it falls as rain, snow, hail, sleet

rain is either absorbed by ground, runoff, or
evaporates
Earth’s Oceans
 Make
up over 70% of the earth’s surface
 Major Oceans:
 Pacific Ocean is the largest – deepest
area of all ocean is Challenger Deep,
11,033 m below sea level, (deeper than
Mt. Everest)
 Atlantic Ocean- also North and south
 Indian Ocean
 Arctic Ocean – smallest ocean covered by
ice, pack ice
Ocean Water
 Salinity
– concentration of all the
dissolved salts, average 3.5%
 Composed of Sodium (31%) and
Chlorine (55%)
 Zones of the Ocean
 Surface Zone – warm, sunlight
 Thermocline – area that gets cold
 Deep Zone – average temperature 2o C
 Functions to absorb and store solar
energy
 Currents move warm and cold water
Biosphere
 Closed
system – matter in the
environment
 Open system - for energy, sunlight