Geology Flashcards
Seismic waves
Waves of energy that travel through the Earth’s crust, caused by earthquakes
Pangaea
A super-continent that existed 225 million years ago. All of the landmasses that existed at this time were joined together to form a super-continent.
Continental Drift
Movement of the plates of the Earth’s crust in relation to each other
Panthalassa
The vast sea surrounding the super-continent of Pangaea
Plate Tectonics
Theory concerning the movement of continental plates
Mantle
Thick layer inside the Earth below the crust. Most of the mantle is solid rock although the upper part is molten rock caller magma.
Convection current
Circular movement that occurs when warmer, less dense fluid particles rise and cooler, denser particles sink.
Continental crust
Plates of the earth’s crust that make up the land
Oceanic crust
One type of earth’s crust that makes up the outer layer. It is thinner than continental crust and made up of dense, heavy rocks such as basalt.
Subduction
When two tectonic plates push against each other and oceanic crust sinks below the less dense continental crust.
Destructive plate boundaries
Convergent boundary where two plates collide
Constructive plate boundaries
Plates that create new land from cooling magma
Oceanic ridges
An area where the tectonic plates move apart allowing magma from the mantle to rise forming new volcanoes.
Hotspots
A localised place where an activity occurs
Folding
Buckling of rocks caused when rocks are under pressure from both side
Anticlines
Folds that bend upwards
Synclines
Folds that bend downwards
Fault
A break in a rock structure causing a sliding movement of the rocks along the break
Rift valleys
A sunken area where two blocks of crust have dropped down between faults
Horst
A block of the Earth’s crust with faults on either side, that has been pushed upward by the forces below
Slip fault
A geological feature where movement along a fault is sideways -that is where the blocks of crust slip horizontally past each other.
Tremors
Vibration on the Earth’s surface caused by an earthquake
Epicentre
The point on the Earth’s centre directly above the site of where an earthquake originates
Focus
The point at which an earthquake begins
Triangulation
Finding a location using at least three different sources of detection
Seismograph
An instrument used to detect and measure the intensity of an earthquake
Richter Scale
A scale that measures the amount of energy released during an earthquake
Primary Waves
Compression waves that move through the earth the same was sound moves through air
S-Waves
Second set of waves to be detected after p-waves. These travel in the form of transverse waves.
Body Waves
Waves that travel through the body of the earth
Seismologists
A scientist who studies earthquakes
Tsunami
A powerful wave triggered by an undersea earth movement
Meltdowns
The melting of a nuclear-reactor core as a result of a serious nuclear accident
Volcanoes
Natural opening in the Earth’s crust connected to molten rock deep inside the crust
Magma
A very hot mixture of molten rock and gases just below the Earth’s surface that has come from the mantle.
Lava
A mixture of molten rock and gases that has reached the Earth’s surface from a volcano.
Volcanic bombs
Large rock fragment that is blown out of erupting volcanoes; also known as lava bombs
Active
Describes a volcano that is erupting or has recently erupted
Extinct
Describes a volcano that has not erupted for thousands of years and is effectively daed.
Dormant
Describes a volcano that has not erupted for more than 20 years but is not considered extinct.
