Task 2 - term 1

• proposed by alfred wegner in 1912 • suggested that continents were once joined together as a supercontinent called “pangea” • over millions of years, continents drifted apart to current position

• harry hess discovered seafloor spreading in 1965 • seafloor spreading occurs at divergent boundaries where new crust if formed when tectonic plates move away from each other • magma rises through the cracks and then solidifies into oceanic ridges, pushing away older rock

• wegner proposed that organisms of the fossils found on different continents were unable to swim across oceans • Pangea should have been connected when they were alive

Africa and South America fit together.

• formed when 2 tectonic plates move towards each other • denser oceanic crust sinks beneath the thick continental crust • oceanic crust sinks into the mantle melting it to create magma • magma solidifies and forms into volcanic arc

• formed when 2 tectonic plates move away from each other • magma rises to fill up space, solidifies and turns into a volcano

• occur when two tectonic plates move towards each other land,land: collision zone - mountain ranges ocean,land: subduction - oceanic trenches, volcanic arcs ocean,ocean: subduction - oceanic trenches, island arcs

• occur when two tectonic plates move away from each other creating a rift land-land: rift valley, inland seas, volcanoes ocean-ocean: oceanic ridges

• occurs where two tectonic plates slide past each other in opposite directions land-land, ocean-land, ocean-ocean: faults, fault lines, earthquakes

• occurs at convergent plate boundary • involves either continental-oceanic or oceanic-oceanic crust • denser crust is pushed downwards into mantle • volcanic arcs, island arcs and oceanic trenches formed

• occur at convergent plate boundary • involve continental-continental crust • both crust have similar density, push each other upwards

• active: currently or recently erupting • dormant: has not erupted recently; expected in future • extinct: has not erupted in human history

• focus: point inside the earth where energy is first released • epicentre: point on earth’s surface directly above the focus

• cause volcanoes when extremely hot magma oushes through thinner parts of the crust • under a hotspot is large active magma chamber • plate moves, volcanoes move, allowing new volcano to form at the hotspot

oceanic-oceanic: underwater volcano continental-oceanic: volcanic arc continental-continental: volcano

• crust: solid • mantle: semi solid • outer core: liquid • inner core: solid

• north american • south american • pacific • erasian • african • australian • antartican

• crater • main vent • ash,cinder,gas • volcanic bombs • secondary vent • secondary cones • magma chamber • magma • lava