RIFT VALLEYS AND OCEAN RIDGES

OCEAN TRENCHES

• form at destructive plate margins (oceanic convergence and oceanic and continental convergence)
• if the convergence is slow then the ocean trench is clearly defined.
• often volcanic activity in the form of island arcs parallel to ocean ridges

Mid Atlantic Ridge

• moves 3-10cm a year
• less than a quarter of the lava reaches teh surface due to intrusive activity
• from South…