Physical Earth Flashcards
Plate Tectonics
A theory that tells us that the earth’s surface is made up of plates, and that these plates move.
Continental Drift
States that the continents had once been joined to form a supercontinent called ‘Pangea’
Lithosphere
The rigid, outer part of earth, consisting of the crust and upper mantle.
What is Pangea?
The supercontinent that existed 300 million years ago and broke up into what earth is presently like
Divergent Boundaries
Where two plates move apart from each other
Convergent Boundaries
Where two plates move together
Transform fault boundaries
Where to plates grind past each other, without production or destruction of the lithosphere
Oceanic ridges
Continuous elevated zones on the floor of all major ocean basins. The rifts at the crest of ridges represent divergent plate boundaries
Rift valleys
Are deep faulted structures found along the axes of divergent plate boundaries. They can form on sea floor or land
Seafloor spreading
Produces new oceanic lithosphere
Subduction zone
Occurs when one oceanic plate is forced down into the mantle beneath a second plate
Continental volcanic arcs
Form in part by volcanic activity caused by the subduction of oceanic lithosphere beneath a continent.
Paleomagnetism
The Natural remnant magnetism in rock bodies; this permanent magnetisation acquired by rock can be used to determine location of magnetic poles at the time
Normal polarity
When rocks show the same magnetism as the present magnetism field
Reverse polarity
When rocks show the opposite magnetism as the present magnetism field
