SUPA Earth System Science unit 7

how many plates are there

seven major plates

what are plates

thin rigid blocks that move over the earth’s mantle

what was the super continent Wegner proposed

Pangaea

what was the ocean Wegner proposed

Panthalassa

How long ago was Pangaea according to Wegner

200 million

What part of the continental drift theory was wrong

the mechanism

what is the plate tectonics theory

lithospheric plates float on the asthenosphere

what are geologic features

earthquakes, mountains, rift valleys, volcanos, trenches

evidence for plate tectonics and continental drift

puzzle-like fit of the continents, matching sequences of rocks, and mountain chains, glacial ages, distribution of organisms

evidence for plate tectonics

earth’s magnetic field, paleomagnetism, magnetic inclination, seafloor spreading, age of ocean crust, and global distribution of earthquakes & volcanos

how old is the crust at the site of the mid-ocean ridge

new ocean crust

what are oceanic trenches the site of

crust distribution

what is paleomagnetism

magnetic alignment either north or south

how do the plates move

convection currents in the asthenosphere, moving mantle drags the plates, it’s powered by heat from the outer core

what types of plate boundaries are there

divergent, convergent, transform

what happens when the plate boundary is divergent

the plates separate

what happens when the plate boundary is convergent

the plates collide

what happens when the plate boundary is transform

the plates slide past each other

what is created when plates diverge

volcanoes, mid-ocean ridge, rift valley (land), shallow earthquakes

what kind of crust is created when plates diverge

new ocean floor is created

what is created when oceanic-continental convergence occurs

volcanoes occur from continental arc, oceanic trenches, and deep earthquakes

why is the ocean plate subducted in oceanic-continental convergence

the ocean plate is subducted because it is denser

what is created when oceanic-oceanic convergence occurs

ocean trench, island arc-volcanoes, and deep earthquakes

what is created when continental-continental convergence occurs

uplifted mountain ranges and deep earthquakes

what is created when transform plate movement occurs

some mid-ocean ridges and shallow earthquakes

what are hotspots

the are volcanoes within a plate

do hotspots create islands of different ages or the same ages

different ages

when was the galaxy formed

13 billion years ago

when was the earth formed

4.6 billion years ago

what is the nebular hypothesis

a huge gas cloud of dust contracts (H &He) and most material is swept towards the center (sun). eddies form (protoplanets) debris creates planets and moons

what was protoearth

it was larger than earth now, with a homogenous composition, and it was bombarded with meteorites

what was the initial atmosphere of protoearth made up of

hydrogen and helium

what created the initial atmosphere

heat from solar radiation (nuclear fusion)

what did the initial atmosphere boil away

there was no magnetic field

how did we get from protoearth to earth

protoearth partially melts and density stratification occurs

what makes up earth’s chemical composition

crust, mantle, and core

what makes up earth’s physical properties

lithosphere, asthenosphere, outer core, and inner core

when was earth’s first atmosphere

4.6 billion years ago

when was earth’s second atmosphere

4 billion years ago

when was earth’s third atmosphere

2 billion

when was the first life

3.5 billion years ago

what was the second atmosphere made of

carbon dioxide and hydrogen