Plate Tectonic Evidence Flashcards
Volcanos and earthquakes cluster around
plate edges
Hotspots leave tracks of extinct volcanoes as moving plates….
get dragged across a static plume
Earth’s outer core generates a strong magnetic field that protects us from……
Radiation
Rocks record the magnetic field
as they form
Magnetism in very old rocks points toward a north pole
far away from today’s pole position
magnetic poles ‘wander’
The rocks used to point in the right direction, but they drifted away from their
original location
When currents in the outer core change direction, the
earth’s magnetic field ‘flips’
Magnets point north during
Magnets point south during
normal fields
reversed fields
Each side of the MOR grows during the same sequence of flipping fields. So they show matching
magnetic strips
Analysis of ocean floor magnetism showed matching _____ on all MOR. This proved that sea-floor was _____
stripes
spreading
We cause GPS satellites to
record plate motion