Soild Earth Dyamics Flashcards
What does the sea floor topography show
There are ridges running through it showing it’s not uniformly flat (Tops of the ridges have the youngest rocks)
Explain how the magnetic North Pole works
The magnetic North Pole flips around as a result of the fluid outer core. Sometimes it flips to become magnetic south. Rock formation is influenced by this and creates magnetic bands
How is rock formation influenced by magnetic fields
Rocks get stripes in them which are magnetic bands, changes from black to white signifies changes in magnetic field. Means rocks at the bottom of the ocean can be dated
What are passive margins
Inactive boundaries between the ocean and continental crust
What is a Raleigh number
How fast the mantle moves
As the mantle convects where is material sent
Upwards
Where are island arc volcanoes formed
Above subduction zones where ocean plates converge
How old is the oldest ocean crust
180-220 myr
What do mantle plumes underneath continental crust create at the surface
Massive outpourings of lava called ‘large igneous provinces’
What provided direct evidence for sea floor spreading
Symmetrical paleomagnetic reversals on either side of the ocean ridges
