GEO Exam 3 Study Guide: Earth Structure and Processes

Lithosphere

Rigid layer including crust and upper mantle.

Mantle

Thick, semi-solid layer between crust and core.

Asthenosphere

Layer allowing tectonic plate motion.

Rock

Assemblage of minerals or single mineral mass.

Mineral

Inorganic solid with specific chemical formula.

Quartz

Most common mineral, composed of SiO2.

Silicates

Mineral family making up 95% of Earth's crust.

Igneous Rock

Formed from cooling of molten material.

Intrusive Igneous Rock

Cools slowly below Earth's surface.

Extrusive Igneous Rock

Cools quickly on Earth's surface.

Pluton

Large intrusive igneous rock body.

Batholith

Largest type of pluton.

Sedimentary Rock

Formed from clasts, shells, or organic matter.

Clastic Sedimentary Rocks

Formed from weathered rock particles.

Chemical Sedimentary Rocks

Formed from crystallization of dissolved minerals.

Metamorphic Rock

Changed by heat and pressure inside Earth.

Felsic

High silica content, lighter colored rocks.

Mafic

Low silica content, darker colored rocks.

Large Crystals

Form from slow cooling of magma.

Small Crystals

Form from rapid cooling of lava.

Geological Cycle

Includes hydrologic, rock, and tectonic cycles.

Granite

Felsic intrusive rock with large crystals.

Basalt

Mafic extrusive rock with small crystals.

Plate tectonics

Theory of lithosphere plates floating over mantle.

Mid-ocean ridges

Underwater mountain systems forming interconnected chains.

Sea-floor spreading

Magma upwelling creates new oceanic crust.

Subduction zone

Area where one plate descends beneath another.

Continental crust

30-70 km thick, made of granite.

Oceanic crust

Dense, dark crust primarily composed of basalt.

Convergent boundaries

Plates collide, causing subduction and earthquakes.

Seismic waves

Energy waves from earthquakes used to study Earth.

Rock cycle

Transformation process between igneous, sedimentary, metamorphic rocks.

Core

Earth's innermost layer, consisting of inner and outer core.

Outer core

Molten iron and nickel generating Earth's magnetic field.

Inner core

Solid iron and nickel under immense pressure.

Mantle

Layer between core and crust, comprising 80% of Earth.

Crust

Outermost solid layer of Earth, 5-10 km thick.

Mohorovicic discontinuity

Boundary between crust and upper mantle identified by seismic waves.

Lithification

Process of turning sediment into sedimentary rock.

Contact metamorphism

Metamorphism due to heat from nearby magma.

Regional metamorphism

Metamorphism caused by pressure over large areas.

Focus

Point inside Earth where an earthquake originates.

Epicenter

Point directly above the focus on Earth's surface.

Depositional environment

Setting where sediments accumulate to form rocks.

Age of the Earth

Estimated at 4.5 billion years via radiometric dating.

Endogenic Energy Sources

Internal heat from Earth's core and radioactive decay.

Exogenic Energy Sources

External energy from the Sun driving surface processes.

Strata

Horizontal layers of sedimentary rock formed over time.

Bedding Planes

Flat surfaces separating individual sedimentary layers.

Joints

Natural cracks in rocks without significant movement.

Pangea

Supercontinent existing 200-300 million years ago.

Heat

Energy from Earth's interior causing mineral recrystallization.

Pressure

Force from tectonic activity increasing rock density.

Ocean Floor Mapping

Technology used to survey and detail oceanic crust.

Sonar

Technique using sound waves to map seafloor features.

Submersibles

Underwater vehicles for detailed ocean studies.

Water

Erodes land and is essential in the rock cycle.

Raw Materials

Natural materials used for product manufacturing.

Fossil Fuels

Coal, oil, and gas formed from buried organic material.

Divergent Plate Boundaries

Where tectonic plates move apart, forming new crust.

Convergent Plate Boundaries

Areas where tectonic plates collide and subduct.

Oceanic-Continental Subduction

Denser oceanic crust subducts, forming volcanic mountains.

Mid-Ocean Ridges

Underwater mountain ranges formed by sea floor spreading.

Volcanic Activity

Eruption of magma due to tectonic movements.

Sedimentary Rock

Rock formed from the accumulation of sediment.

Chemical Weathering

Breakdown of rocks through chemical reactions.

Erosion

Process of transporting soil and rock by natural forces.

Oceanic-continental convergence

Denser oceanic crust subducts, forming volcanic mountain ranges.

Oceanic-oceanic convergence

One oceanic plate subducts, creating volcanic island arcs.

Continental-continental convergence

Less dense crust collides, forming massive mountain ranges.

Transform plate boundaries

Plates slide past each other, causing earthquakes.

Pacific Ring of Fire

Volcanoes along Pacific plate margins from subduction.

Hot spots

Volcanic activity beneath oceanic and continental crust.

Continental shield

Region where craton is exposed at the surface.

Faulting

Rocks shift along fractures due to stress.

Normal fault

Rocks pulled apart, moving vertically along fault.

Reverse fault

Rocks pushed together, causing collapse and landslides.

Thrust fault

Low-angle reverse fault shifting overlying block.

Active volcano

Erupted at least once in recorded history.

Sea-floor spreading

New oceanic crust forms at mid-ocean ridges.

Volcano

Structure with a central vent for magma.

Cinder cone

Small, steep hill formed from cinders.

Caldera

Basin-shaped depression from volcanic summit collapse.

Effusive eruptions

Low-viscosity magma outpouring, creating large lava volumes.

Shield volcano

Broad, gently sloping volcano from fluid lava flows.

Explosive eruptions

Violent magma explosions driven by pressure build-up.

Composite volcano

Tall, steep-sided volcano from layered eruptions.

Tectonic plate movement speed

2 to 15+ cm per year.

Shallow earthquakes

Lower magnitudes, occur at shallow depths.

Deep earthquakes

Higher magnitudes, occur at greater depths.

Tectonic activity

Occurs at plate margins and edges.

Volcano Distribution

10-20% of volcanoes above sea level.

Extinct volcanoes

Can erupt unexpectedly, creating safety risks.

Dormant volcanoes

Appear inactive but can erupt suddenly.

Viscosity of magma

Resistance to flow; more silica increases viscosity.

High viscosity magma

Thick, traps gases, leads to explosive eruptions.

Low viscosity magma

Runny, allows gas escape, results in gentle eruptions.

Nuee ardente

Fast-moving, destructive flow of hot gases and ash.

Volcanic ash

Small particles that can travel long distances.

Felsic volcanic eruption

High silica, sticky, and explosive eruptions.