Science test Mar '23

Rock that makes up oceanic crust

Forms at convergent CC boundaries

Forms at convergent OC boundaries

plates moving towards each other, 3 possible scenarios (CC, OO, CO)

plates moving apart, formation of new crust created at rift valleys/mid-ocean ridges, mild volcanic eruptions & shallow earthquakes

plates moving towards each other, formation of collisional mt. ranges, common earthquakes, overriding of C plates, no volcanoes or subduction of C crust

plates moving towards each other, formation of mt. ranges on the C side, trenches on the O side, explosive volcanoes & earthquakes

plates moving towards each other, formation of volcanic island arcs & trenches, explosive volcanoes & earthquakes, subduction of which crust is denser (older)

Rigid layer made up of crust & upper mantle

Plastic layer made up of upper mantle below lithosphere

More rigid than asthenosphere but still flows

Liquid, flows

Solid, doesn’t flow

Boundary between crust and mantle

Created from basaltic lava erupting underwater that cools quickly

occurs bc cold slabs of oceanic lithosphere are denser than warm asthenosphere, so they sink

Rock that makes up continental crust

Crust above ocean

Rock that makes up the mantle

plumes of mantle rising up that are random

massive slab of lithosphere

Studied the seafloor, proposed that mid-Atlantic ridge was spreading center

Came up with the continental drift hypothesis

When the south pole is the magnetic pole

results from elevated position of oceanic ridge, causes slabs of lithosphere to slide down ridge

Forms from upwarping of the lithosphere.

As plates move apart, asthenosphere rises to surface & melts (lower pressure), once it cools, new ocean crust is formed. Continents move apart, powered by convection

The sinking of lithosphere into the asthenosphere, where plates converge

• plates moving past each other horizontally, formation of faults, no up or down motion of plates, shallow earthquakes, no subduction or volcanism

Forms at convergent OC boundaries

Forms at convergent OO boundaries

Scientific revolution that unfolded between 1915 and 1970, states the Earth’s surface is broken into rigid tectonic plates that are in constant motion

Supercontinent, or single continent, that existed 200-300 mil ya

The continents were once joined together in a single large landmass called Pangea

Every so often, the magnetic poles of Earth reverse, so that the magnetic north pole is now located over the geographic south pole

Earth is a magnet w/ magnetic fields at poles, every 300,000 years, magnetic poles reverse, as seafloor spreads, it creates bands of equal polarity moving away from each other at equal speeds

Made first map of North Atlantic in 1957, discovered huge mt. ranges in the middle of both oceans, contributed to plate tectonics theory

Interpreted magnetic stripes on seafloor as products of steady creation of new ocean crust over geologic time

When the magnetic poles and geographical poles are lined up

Rift that stopped formation into sea and ocean ridge for an unknown reason