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Earth’s Structure
KEY VOCABULARY
GEOLOGY
• STUDY OF PLANET EARTH’S HISTORY,
STRUCTURE, AND COMPOSITION
• A GEOLOGIST IS A SCIENTIST WHO
STUDIES THE EARTH
• UNIFORMITARIANISM IS THE COCEPT
THAT THE PROCESS THAT HAPPEN
TODAY ARE THE SAME AS THE ONES
THAT HAPPENED IN THE PAST
EARTH’S LAYERS
• CRUST: ROCKY OUTER LAYER THAT WE
LIVE ON.
• CONTINENTAL CRUST: LAND
• OCEANIC CRUST: OCEAN SEA FLOOR
• THE CRUST RANGES FROM 5-75
KILOMETERS IN THICKNESS
MANTLE
• A LAYER OF HOT, SOLID ROCK,
ROUGHLY 2850 KILOMETERS THICK
• LITHOSPHERE: RIGID LAYER OF
ROCK AT THE UPPERMOST PORTION
OF THE MANTLE
• ASTHENOSPHERE: SOFTER, WEAKER
ROCK THAT FLOWS SMOOTHLY
• MESOSPHERE: STIFFER ROCK
EXTENDS DOWN TO THE CORE
CORE
• LARGE METAL SPHERE OF METAL IN
THE EARTH’S CENTER
• 3480 KILOMETERS THICK
• MOSTLY THOUGHT TO BE IRON AND
NICKEL
• OUTER CORE IS LIQUID METAL
• INNER CORE IS SOLID
MINERALS
• ROCK: SOLID COMBINATION OF
MINERALS
• MINERAL: NATURALLY OCCURING,
INORGANIC SOLID WITH A CRYSTAL
STRUCTURE, & CHEMICAL COMPOSITION
• INORGANIC: LIVING THINGS DID NOT
PRODUCE THE MATERIAL
CHARACTERISTICS
• CRYSTAL STRUCTURE: ATOMS ARE
ARRANGED IN A GEOMETRIC PATTERN
• COLOR: IDENTIFIES MINERALS
• STREAK: COLOR OF IT POWDER OR
SCRATCH
• LUSTER: HOW IT REFLECTS LIGHT
• DENSITY: DEPENDS ON ATOMIC
MASSES
CHARACTERICTICS CONT.
• HARDNESS: RESISTANCE OF A
MINERAL TO SCRATCHING
• FRACTURE: HOW THE MINERAL
BREAKS
• CLEAVAGE: TYPE A FRACTURE THAT IS
REGULAR ALONG A WELL-DEFINED
PLANE
IGNEOUS ROCK
• ROCK IS FORMED WHEN MAGMA COOLS
AND SOLIDFIES EITHER AT THE SURFACE
OR INSIDE THE EARTH
• FORMED BY MAGMA, MOLTEN ROCK AND
GAS
• LAVA IS MAGMA THAT FLOW FROM
VOLCANOS
• INTRUSIVE: UNDERGROUND HARDENED
ROCK
• EXTRUSIVE: FORMS AT EARTH’S SURFACE
SEDIMENTARY ROCK
• FORMS OVER TIME AS SEDIMENT IS
DEPOSITED, SQUEEZED, AND CEMENTED
TOGETHER
• SEDIMENT IS SMALL, SOLID PIECES OF
MATERIAL THAT COMES FROM ROCK OR
LIVING ORGANISMS
• CLASTIC ROCK: BROKEN FRAGMENTS OF
MANY ROCKS CEMENTED TOGETHER
• CHEMICAL ROCK: MINERALS PRECIPITATE OUT
OF SOLUTION
• ORGANIC ROCK: FORMED FROM DEAD
ORGANISMS
METAMORPHIC ROCK
• ROCK THAT IS CHANGED BY
PRESSURE, TEMPERATURE, OR
REACTIONS FROM HOT WATER
• FOLIATED ROCKS: ROCKS THAT HAVE
PARALLEL BANDS OR LAYERS
ROCK CYCLE
• A SERIES OF PROCESSES IN WHICH
ROCKS CONTINUOUSLY CHANGE
FORM
PLATE TECTONICS
• THEORY THAT EXPLAINS THE
FORMATION AND MOVEMENT OF THE
EARTH’S PLATES
• PANGAEA: ALL LAND
• CONTINENTAL DRIFT: EXPLAINS HOW
CONTINENTS FIT TOGETHER
• MID-OCEAN RIDGE: CHAIN OF
UNDERWATER MOUNTAINS
• SEA-FLOOR SPREADING: NEW OCEAN
IS CREATED AT MID-OCEAN RIDGES
AS OLDER CRUST MOVES AWAY
• SUBDUCTION: OCEANIC PLATES SINK
INTO THE MANTLE
• TRENCH: BENDING OF PLATES AT
SUBDUCTION ZONES FORMING A
DEPRESSION
BOUNDARIES
• DIVERGENT BOUNDARY: WHEN
PLATES MOVE APART
• CONVERGENT BOUNDARY: WHEN
PLATES MOVE TOGETHER
• TRANSFORM BOUNDARY: PLATES
SLIDE PAST EACH OTHER
EARTHQUAKE
• MOVEMENT OF THE EARTH’S LITHOSPHERE
ROCKS SUDDENLY SHIFT
• SEISMIC WAVES: SMALL AMOUNTS OF
ENERGY RELEASED CARRIED BY
VIBRATIONS
• TSUNAMI: LARGE SEA WAVE GENERATED
BY AN UNDERWATER EARTHQUAKE,
VOLCANO, OR LANDSLIDE
• STRESS: FORCE THAT SQUEEZES
ROCK TOGETHER, STRECTHES THEM,
OR PUSHES THEM IN DIFFERENT
DIRECTIONS
• FAULT: BREAK IN THE MASS OF THE
ROCK ALONG WHICH MOVEMENT
OCCURS
• FOLD: BEND IN THE LAYERS OF ROCK
EARTHQUAKES
• OCCUR BECAUSE STRESS FACTORS
EXCEED THE STRENGTH OF THE ROCK
• FOCUS: WHERE THE EARTHQUAKE BEGINS
• EPICENTER: EARTH’S SURFACE DIRESTLY
ABOVE THE FOCUS
• P-WAVE: LONGINTUDINAL WAVES
• S-WAVE: TRANSVERSE WAVES
• SURFACE WAVES: WAVES DEVELOPING AT
EARTH’S SURFACE, LONGER, CAUSES
MORE DAMAGE
MEASUREMENT
• EARTHQUAKES ARE MEASURED WITH
SIESMOGRAPHS WHICH DETECT AND
RECORD SEISMIC WAVES
• RICHTER SCALE, MOMENT
MAGNITUDE SCALE, AND MODIFEID
MERCALLI SCALE IDENTIFY HOW
MUCH ENERGY IS RELEASED