Type of Boundary
Description/Features of Plate Boundary
Example
Diverging Boundary
Notes
 Lithosphere is lifted and spread apart by convection currents
 Magma flows into crack and solidifies
 New crust being made at boundary
 Process repeats
Effects
 Sea Floor Spreading
 Submarine mountain ranges
 Earthquakes, volcanic activity
 Widening of ocean basins
Mid – ocean
ridge
Notes
 continental plate arches upward from convection current and
pulls apart to form a rift with faulting (cracks)
 the blocks slide downward
 streams and rivers fill in to make a linear lake, this may
eventually lead to a new ocean basin
East Africa
Rift,
The Red Sea
Oceanic
Diverging Boundary
Continental
Effects-a rift valley occupied by a linear lake or shallow arm of
the ocean, earthquakes occur along the faults, volcanic activity
sometimes occurs within the rift valley
Sliding (Transform)Boundary
Two plates slide against each other in a sideways motion. As
two plates slide past one another, in a transform boundary,
neither plate is added to at the boundary, nor destroyed. The
fracture formed between the two plates is referred to as a fault
line
The result of two massive plates pushing against one another is
that massive amounts of energy build up. Occasionally this
energy is released suddenly in the form of large earthquakes.
California's
San Andreas
Conversion Boundary
Continent – Continent
Notes
 powerful collision occurs
 deformed rock, folding and faulting of plates 100’s of miles
into the plate
Himalaya
Mountains;
Ural
Mountains
Effects-intense folding, broad folded mountain range,
earthquake activity, shortening and thickening of the plates in
the collision zone
1.
Conversion Boundary
Ocean – Continent
Notes
 thinner, more dense oceanic plate is overridden by the
thicker, less dense continental plate (subduction). Ocean
trenches occur at the zone of subduction
 at depths of 100 miles, partial melting begins, magma
chambers form and may rise and break through the crust to
form volcanoes
Volcanic arc
chains onshore
(EXAMPLE:
Andes,
Cascades)
Effects- earthquakes along the continental margin, ocean
trench offshore, volcanic eruptions inland
Conversion Boundary
Ocean – Ocean
Notes
 one oceanic plate will subduct, remelt at depths near 100
miles; magma chambers that are produced may start to rise
and break through the surface to form a volcano; the cone
will be below sea level but may eventually grow higher;
produces an island chain and in time the islands grow
larger and an elongated landmass is created
Effects- earthquakes, oceanic trench, volcanic islands
Japanese
Islands,
Aleutian
Islands