7th grade science 11 Flashcards
Continental drift
Wegener’s hypothesis that all continents were once connected in a single large landmass that broke apart and drifted slowly to their current positions
Pangaea
A single landmass composed of all the continents joined together
Sea floor spreading
Hess’s theory that magma under Earth’s crust is forced up towards the surface at the mid ocean ridges, forming new seafloor
Asthenosphere
Plastic like layer of earth on which the lithosphere plates move
Convection currents
Cycle of heating, rising, cooling, and sinking
Lithosphere
Rigid layer of Earth made of the crust and upper mantle on the asthenosphere
Plate
Large section of Earth’s crust layer and upper mantle layer that moves around on the asthenosphere
Plate tectonics
Theory that Earth’s crust and upper mantle are broken into plates that move around on a plastic like layer of mantle
Earthquake
Movement of the ground that occurs when rocks inside Earth reach there elastic limit, break suddenly, an experience rebound
Epicenter
Point on Earth’s surface directly above the earthquakes focus
Fault
Fracture that occurs where rocks break which results in movement of opposing sides
Focus
Point deep inside Earth where energy is released, causing an earthquake
Magnitude
Measure energy released by an earthquake
Seismic safe
Describes the ability of structures to stand up against vibrations caused by an earthquake
Seismic waves
Earthquake waves including primary waves, secondary waves, and surface waves
