1.2 plate tectonics Flashcards
what is the evidence of seafloor spreading?
where two plates move away from each other at divergent plate boundaries, seafloor spreading occurs.
magma forms deep within the earth rises through the mid-ocean ridge
new oceanic crust is formed.
why does evidence of seafloor spreading support plate tectonic theory?
The age of rocks.
rocks nearer the crest of the mid-ocean ridge are the youngest
rocks further away from the mid-ocean ridge are progressively older.
New oceanic crust is created as seafloor spreading continues
Little sediment accumulation is found at oceanic trenches as older crust is destroyed at oceanic trenches, hence oceanic crusts are younger than continental crusts.
Proving that new crust is continually formed at divergent boundaries at mid ocean ridges and as plates move, older crust is destroyed further away at oceanic trenches.
what is seafloor spreading?
When two oceanic crust diverge, magma rises from the mantle to fill the gap between the plates as they move apart. New seafloor is formed when the magma cools and solidifies.
