click below
click below
Normal Size Small Size show me how
Earth & Plate Tecton
Earth and Plate Tectonics Unit
Term | Definition |
---|---|
inner planet | planets closest to the sun, rocky Mercury, Venus, Earth, Mars |
terrestrial planet | rocky planet, all of the inner planets |
rotation | Earth spinning on its axis one time in 24 hours |
revolution | Earth orbiting the sun one time in 365 1/4 days |
lithosphere | hard, rocky plates includes upper mantle and the crust |
continental crust | top, hard, rocky layer that includes the continents |
oceanic crust | top, hard rocky layer underneath the oceans more dense than the continental crust |
convection currents | circulation of material due to temperature and density (warm rises, cooler sinks) |
inner core | solid, rocky, most dense layer in the center of Earth made of iron and nickel |
outer core | liquid iron and nickel that circulates around the inner core |
mantle | the large middle layer of Earth where the convection currents occur, ranges from solid to liquid |
asthenosphere | slush-like middle mantle where the convection currents occur |
Pangea | supercontinent that occurred 280,000,000 years ago |
Continental Drift | Hypothesis by Alfred Wegener who said that the continents are in motion |
Plate tectonics | Theory that says the Earth is made up of plates that move |
mid-ocean ridge | an underwater mountain range built by seafloor spreading |
Seafloor spreading | process in which magma erupts between two plates and creates new oceanic crust pushing the old crust outwards, usually a mid-ocean ridge is formed |
subduction | when one plate sinks below another plate, causes volcanoes, made by converging plates |
convergent | two plates move towards each other |
divergent | two plates move away from each other, causes seafloor spreading |
transform | plates slide past one another |
fault | break in the lithosphere |
earthquake | rapid release of energy that occurs when stress builds up along a plate boundary or a fault |
epicenter | the spot on the Earth's surface directly above a focus |
focus | the spot on a fault line where energy is release in a seismic wave |
seismic wave | transfers energy through the ground during an earthquake |
primary wave | seismic wave that arrives first, a push pull motion |
secondary wave | seismic wave that arrives second, it moves at a right angle to the motion |
seismometer | tool used to measure seismic waves |
volcano | a vent where magma comes out of the Earth's crust |
Continent to Continent converging plates | cause mountains like the Himalayas |
Ocean to Ocean converging plates | cause ocean trench like the Mariana trench, and maybe an arch of volcanic islands |
Ocean to Continent converging plates | cause a subduction zone and mountain chain that includes volcanoes, like Mt St Helens and the Cascade Mountains |
Oceanic Diverging plates | cause mid ocean ridges and seafloor spreading, like the MidAtlantic Ridge |
Continental diverging plates | cause rift valleys on land such as the one in Iceland |
Ring of Fire | area around the Pacific Ocean where most of the volcanoes and earthquakes in the world occur |
Hot spot | when convection currents make magma plume up through the crust and create a volcano - NOT on a plate boundary |
viscosity | the thickness of the lava flow |
mafic lava | fast, hot, thin lava, quiet eruptions |
felsic lava | thick, slow lava, explosive eruptions |
lava | molten rock above ground |
magma | molten rock below ground |
shield volcano | gentle slope, mafic lava, quiet eruptions like Mauna Loa, Hawaii |
cinder cone volcano | steep cone shape, felsic lava (cinders), explosive eruptions |
composite volcano | stratovolcano, both felsic and mafic lava, alternating explosive and quiet eruptions, Mt. St. Helens |
pyroclastic flow | hot, fast moving cloud of ash and dust from a volcano |
Volcanic ash | very small pieces of rock and glass that flows from a volcano |