Transcript Earth`s interior volc eq4

Sea Floor Spreading
• The process by which new
oceanic lithosphere forms
as magma rises to the
surface and solidifies
– Evidence for continental drift
• DIVERGENT plate
boundaires
• Mid-ocean ridges are
located where there is sea
floor spreading.
– Example: Mid-Atlantic Ridge
Causes of Tectonic Plate
Motion
• Changes in density
within the athenosphere
• Energy comes from
center of Earth
• Convection currents
*important
– Heated rock expands
and rises (less dense)
– Cool rock contracts and
sinks (more dense)
Convection currents
• Definition - transfer of energy
by flow of a heated substance
– Hot liquids - RISE (less dense)
– Cold liquids - SINK (more dense)
• Why? When heated molecules
expand and are less dense
• Interior of the earth (think lava lamp)
– Center is hot and liquid magma rises
• Less dense
– Rises to crust and pushes it
• Give convergent and divergent boundaries
– Cools and sinks back down to the center
• More dense
Convection currents
https://www.youtube.com/watch?v=ryrXAGY1dmE
Awesome video
How is it measured?
• In centimeters per year
• GPS (global positioning
system) from satellites
– Scientists record the time
it takes for GPS ground
stations to move a given
distance
– This allows them to
measure the speed of the
plates motion
Folding
• Bending of rocks
because of stress
• Types
– Anticlines: downward
• Like a sad face
– Synclines: upward
• Like a smile face
– Monocline: both ends
are horizontal
Faulting
• The surface along which rocks break and
slide past each other