divergent boundaries plates move away from each other marine –ocean basins open & seafloor...
TRANSCRIPT
Divergent BoundariesDivergent Boundaries
• Plates move away from each other
• Marine– Ocean basins open & seafloor created
• Continental– Rift zones & new ocean basins created
Rift ZoneRift Zone
• East African Rift Valley
• Kilimanjaro and Mount Kenya
• Graben
Divergent BoundariesDivergent Boundaries
Transform BoundariesTransform Boundaries
• Plates slide past one another
• Neither created nor destroyed
Convergent BoundariesConvergent Boundaries
• Plates move toward each other
• Marine– Trenches, destruction of sea floor & closing of
ocean basins
• Continental– Creation of mountain ranges
Convergent BoundariesConvergent Boundaries
• Three types:
1. Ocean-Continent Convergence
2. Ocean-Ocean Convergence
3. Continent-Continent Convergence
Ocean-Continent ConvergenceOcean-Continent Convergence
Mount St. HelensMount St. Helens
Ocean-Ocean ConvergenceOcean-Ocean Convergence
Continent-Continent ConvergenceContinent-Continent Convergence
HimalayasHimalayas
Continental MarginsContinental Margins
• Two types:
1. Passive– Closest to the divergent
plate boundary
2. Active– Closest to the
convergent plate boundary
Mechanisms of MotionMechanisms of Motion
• Convection cells??
• Ridge push force
• Slab pull force
Rates of MotionRates of Motion
• 1 – 20 cm per year
• Average rate of 5 cm/yr
• Slow spreading rates– Steep slopes
• Fast spreading rates– Gentle slopes
IcelandIceland
Hawaiian IslandsHawaiian Islands
Hydrothermal VentsHydrothermal Vents