Chapter 2
A Living Planet
The Solar System
 Consists of the sun and nine
planets and other celestial
bodies
–Comets: spheres of ice and
dust
–Asteroids: large chunks of
rocky material
The Structure of the Earth
 Earth has 3
layers
–Core: iron and
nickel
–Mantle: magma
–Crust: thin
layer of rock
The Structure of the Earth
 Atmosphere: layer of gases
 Lithosphere: includes crust and upper
mantle
– Forms ocean floor
– Forms 7 continents: Asia, Africa, North
America, South America, Europe,
Australia, Antartica
 Hydrosphere: water elements of earth
 Biosphere: where plants and animals live
The Structure of the Earth
 Continental Drift Theory
–Earth was once a
supercontinent that divided
and slowly drifted apart over
millions of years
Bodies of Water
 Oceans and Seas
– Covers 71% of earth
– Pacific Ocean, Atlantic Ocean, Indian Ocean,
Artic Ocean
– Circulates through 3 basic motions
 Currents: like rivers in ocean
 Waves: swells or ridges produced by wind
 Tides: created by gravitational pull of moon
or sun
Bodies of Water
 Hydrologic Cycle
–The continuous
circulation of
water between
the atmosphere,
the oceans, and
the earth
Bodies of Water
 Lakes
– Hold more than 95% of earth’s fresh
water supply
– Salt water lakes
 Rivers and streams
– Flow through channels and move water
to or from larger bodies of water
– Drainage basin: are drained by major
river
Bodies of Water
 Ground Water
–Water held in pores of rock
–Water table: level at which rock is
saturated
Can change depending on
amount of precipitation
Landforms
 Naturally formed features on the surface of
the earth
– Volcano
– Strait
– Island
– Delta
– Marsh
– Oasis
– Flood plain
– Bay
-Plateau
-Mesa
-Prairie
-Steppe
-Valley
-Canyon
-River mouth
-Harbor
-Cataract
-Glacier
-Cliff
-Mountain
-Butte
-Swamp
-Cape
-Sea level
Landforms
 Oceanic landforms:
–Continental shelf: earth’s surface from
edge of a continent to deep part of the
ocean
–Ridges: places where new crust is being
formed on edges of tectonic plates
–Islands: formed by volcanic action,
deposits of sand, or deposits of coral
skeletons
Landforms
 Continental landforms
– Relief: the difference in elevation of a
landform from its lowest point to its
highest point
 Mountains, hills, plains, plateaus
– Topography: the combination of the
surface shape and composition of the
landforms and their distribution in a
region
Internal Forces Shaping the Earth
 Plate tectonics
 Earthquakes
 Volcanoes
Plate Tectonics
 Tectonic Plates: enormous moving pieces of
the earth’s lithosphere
– Move in 1 of 4 ways
 Spreading or moving apart
 Subduction or diving under another
plate
 Collision or crashing into one another
 Sliding past each other in a shearing
movement
Plate Tectonics
 3 types of boundaries mark plate
movement
– Divergent boundary: move apart
horizontally
– Convergent boundary: plates collide; one
goes under the other or both plates
crumble
– Transform boundary: plates slide past
one another
– Fault: fracture in the earth’s crust
Volcanoes
 Crack in earth’s
surface where
magma, gases,
and water from the
lower part of the
mantle pour out
 Lava: magma that
has reached
earth’s surface
Volcanoes
 Ring of Fire
– Zone around rim of
the Pacific Ocean
– Eight major plates
meet here
– Volcanic action and
earthquakes often
occur
– Hot springs and
geysers
Earthquakes
 Violent movement of the earth
 Occurs when plates slide past each
other at a fault
 Seismograph: detects earthquakes
Earthquakes
 Location
– Focus: where earthquake begins
– Epicenter: directly above focus on the
earth’s surface
 Damage
– Richter Scale: relative strength of
earthquake
 Tsunami
– Giant wave in ocean
External Forces Shaping the Earth
Weathering
Erosion
Building soil
Weathering
 Physical and chemical
processes that change the
characteristics of rock on or
near the earth’s surface
 Creates sediment; smaller
pieces of rock
–Mud, sand, silt
Weathering
 Mechanical weathering:
processes that break rock into
smaller pieces
–Does not change composition
of rock
–Frost, plant roots, human
activity
Weathering
 Chemical weathering: rock is
changed into a new substance as a
result of interaction between
elements in the air or water and
minerals in the rock
–Iron rusting, acid rain
–Occurs more in warm, moist
climates
Erosion
 Occurs when weathered
material is moved by the action
of wind, water, ice or gravity
 Transporting agent must be
present
Erosion
 Water erosion
–Water flows in streams or rivers
Erode vertically and horizontally
Delta: fan-like landform that occurs
when a river enters the ocean
–Wave action along coastline
Can reduce or increase beaches
Erosion
 Wind erosion
–Transports and deposits material in
other locations
–New landforms may be produced
Sand dunes
–Loess
Wind blown silt and clay sediment
that produce very fertile soil
Erosion
 Glacial erosion
–Glacier: large, long-lasting mass of
ice that moves because of gravity
–Glaciation: the changing of
landforms by slowly moving
glaciers
–Moraine: when rocks left behind by
a glacier form a ridge or hill
Building Soil
 Soil: loose mixture of weathered rock,
organic matter (humus), air and water
 Soil factors
–Parent material
–Relief
–Organisms
–Climate
–Time