Science test Mar '23

Basalt

Basalt

Rock that makes up oceanic crust

Collisional mt. range

Forms at convergent CC boundaries

Continental volcanic arc

Forms at convergent OC boundaries

Convergent boundary

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

Divergent boundary

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

CC convergent boundary

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

CO convergent boundary

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

OO convergent boundary

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

lithosphere

Rigid layer made up of crust & upper mantle

asthenosphere

Plastic layer made up of upper mantle below lithosphere

mesosphere

More rigid than asthenosphere but still flows

outer core

Liquid, flows

inner core

Solid, doesn’t flow

Moho

Boundary between crust and mantle

Pillow basalt

Created from basaltic lava erupting underwater that cools quickly

slab pull

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

granite

Rock that makes up continental crust

oceanic crust

Crust above ocean

peridotite

Rock that makes up the mantle

hot spot

plumes of mantle rising up that are random

tectonic plate

massive slab of lithosphere

Harry hess

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

Alfred wegener

Came up with the continental drift hypothesis

reverse polarity

When the south pole is the magnetic pole

ridge push

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

rift valley

Forms from upwarping of the lithosphere.

seafloor spreading

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

subduction

The sinking of lithosphere into the asthenosphere, where plates converge

transform boundary

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

trench

Forms at convergent OC boundaries

volcanic island arc

Forms at convergent OO boundaries

plate tectonics theory

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

Pangea

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

continental drift hypothesis

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

pole reversal

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

paleomagnetism

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

Marie tharp and bruce heezen

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

Frederick vine and drummond matthews

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

normal polarity

When the magnetic poles and geographical poles are lined up

failed rift

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