Download Alfred Wegener (1910 ) Continental Drift

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Transcript 
Alfred Wegener
(1910 )
Continental Drift
Continental Drift
Evidence
Q. 1) Who studied sea-floor spreading and when?
Harry Hess
(1960’s)
Sea Floor Spreading
Q. 2) What is sea-floor spreading?
The theory that molten from mid-ocean ridges creates
new crust and spreads older crust apart.
Q. 3) What is subduction?
When older crust is pushed into a
deep-sea trench and sinks back
towards the mantle.
Sea Floor
Spreading
Evidence
The next slide will walk through the evidence…
Harry Hess’s Sea Floor Spreading
Evidence #3 – Drilling Samples
Shows the age of crust is younger beside MOR –
proves new crust is added (& pushes sea-floor apart)
Evidence #1 – Molten material
(what pushes crust apart)
= North
= North
MID OCEAN RIDGE
OLD
NEW
Sea Floor Spreading
MANTLE
NEW
OLD
Sea Floor Spreading
Evidence #2 – Magnetic stripes
Proves molten rock comes out of MOR. The
pattern can only shift in liquid (not solid crust).
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