 J Tuzo Wilson- lithosphere is broken into separate sections called plates.  Combine all information from continental drift, sea-floor spreading, and Earth’s plates into one scientific theory.  Theory - remember is a well-tested concept explained by a large range of observations

 Plates float on top of the lithosphere  Convection currents rise beneath the lithosphere  Convection currents cause plates to move causing Earth’s surface to change  Earth’s surface changes include volcanoes, mountain ranges, and deep ocean trenches

 Plate boundaries- defined as where the edges of the plates meet.  Three types of boundaries  Convergent boundary  Divergent boundary  Transform boundary

 Defined as a place where 2 plates come together, or converge, causing a collision  2 continental plates collide- mountains form  OR continental and oceanic plate collide or oceanic and oceanic collide- one subducts (denser) beneath the other causing a trench

DEEP OCEAN TRENCHMOUNTAIN FORMATION

 Defined as 2 plates that move apart, or diverge, usually occur at the mid-ocean ridge.  Can occur in the middle of the continent to form rift valleys

MID- OCEAN RIDGERIFT VALLEY

 Defined as 2 plates that slip past each other  Typically cause earthquakes