Unit & Plate Tectonics

Vocabulary:

Conduction - The transfer of heat through a material without the movement of the material itself.

Radiation - The transfer of energy through electromagnetic waves, such as light or heat, without requiring a medium.

Convection - The transfer of heat in a fluid (liquid or gas) where the warmer, less dense part rises and the cooler, denser part sinks, creating currents.

Thermal Conductivity - A measure of how well a material allows heat to pass through it.

Heat Transfer - The movement of thermal energy from one object or substance to another.

Insulator - A material that does not conduct heat well.

Conductor - A material that allows heat to pass through it easily.

Continental Drift - The theory that continents have moved over geological time and were once part of a single landmass.

Seafloor Spreading - The process by which new oceanic crust forms at mid-ocean ridges and spreads outwards.

Paleomagnetism - The study of Earth's past magnetic field recorded in rocks, helping to support the theory of plate tectonics and seafloor spreading.

Wegener’s Hypothesis - The idea proposed by Alfred Wegener that continents were once joined together in a supercontinent (Pangaea) and have since drifted apart.

Evidence for Continental Drift:

Fossil Evidence - Similar fossils found on continents that are now widely separated.

Rock Formations - Similar rock layers and geological features across continents.

Glacial Evidence - Evidence of ancient glaciers in now-warm areas, suggesting continents were once located closer to the poles.

Fit of the Continents - The observation that continents like South America and Africa seem to fit together like a jigsaw puzzle.

Tectonic Plates - Large, rigid pieces of Earth’s lithosphere that move and interact at plate boundaries.

Divergent Boundary - Where two plates move away from each other, often causing seafloor spreading.

Convergent Boundary - Where two plates move toward each other, often causing mountain formation or subduction zones.

Transform Boundary - Where two plates slide past each other horizontally, leading to earthquakes.

Tension - Stress that stretches the material (at divergent boundaries).

Compression - Stress that squeezes the material (at convergent boundaries).

Shear - Stress that causes sliding or twisting (at transform boundaries).

Strain - The deformation or change in shape of a material due to stress.

Faults:

Normal Fault - A fault where the hanging wall moves downward relative to the footwall (caused by tension).

Reverse Fault - A fault where the hanging wall moves upward relative to the footwall (caused by compression).

Strike-Slip Fault - A fault where the movement is primarily horizontal (caused by shear stress).

Lithosphere - The rigid outer layer of Earth, including the crust and upper mantle.

Asthenosphere - A semi-fluid layer beneath the lithosphere, allowing tectonic plates to move.

Earthquakes and Seismic Waves:

Seismic Waves - Waves of energy that travel through Earth’s layers due to an earthquake or other seismic event.

Primary (P) Waves - The fastest seismic waves, compressional in nature, that can travel through both solid and liquid.

Secondary (S) Waves - Seismic waves that are slower than P-waves and can only travel through solids, moving in a transverse motion.

Surface Waves - Seismic waves that travel along the Earth’s surface and are responsible for most of the damage during an earthquake.

Epicenter - The point on Earth's surface directly above the earthquake's focus (where the earthquake originates).

Focus (Hypocenter) - The point beneath Earth's surface where an earthquake originates.

Seismogram - A record of the seismic waves detected by a seismometer, used to determine the location and magnitude of an earthquake.

Seismometer - An instrument used to detect and measure seismic waves.

Triangulation - The method used to determine the epicenter of an earthquake by using data from multiple seismometer locations.

Magnitude - A measure of the energy released during an earthquake, typically measured by the Richter scale.

Intensity - A measure of the earthquake’s effects on people, buildings, and the Earth's surface, typically measured by the Mercalli scale.

Richter Scale - A scale that measures the magnitude of an earthquake, based on the amplitude of seismic waves.

Mercalli Scale - A scale that measures the intensity of an earthquake, based on observed effects on people, buildings, and the Earth's surface.