CONVERGENT BOUNDARY Oceanic Plate Continental Plate Nazca Plate South American Plate = Andes Pacific Plate North American Plate = Cascade Range Deep Ocean Trenches The subduction of the oceanic plate causes... Volcanic Mountains
Other Convergent Boundaries with Oceanic/Continent Collisions • Check out where there is an ocean-continent collision: • Cascade Mountains • Andes Mountains Note the volcanic mountains... Note the deep oceanic trench off the coast... Evidence of subduction Earthquakes happen any time the plates move relative to one another… Like here!
CONVERGENT BOUNDARY TRENCHES happen at subduction zones TRENCH
Convergent Boundaries with Ocean – Oceanic Collisions • Check out places in the world where there is an ocean-ocean collision: • Philippines • Mariana Islands • Japan • Aleutian Islands Note the Islands Arcs... They are volcanic islands that grew up from the base of the ocean. This is the same process that cause volcanic mountains (Andes, Cascades) on land, but since these begin on the floor of the ocean, they are not quite as tall. Note the deep oceanic trenches off the coast... Earthquakes happen any time the plates move relative to one another… Like here!
CONVERGENT BOUNDARY Oceanic Plate Oceanic Plate Pacific Plate Philippine Sea Plate Pacific Plate Japan Pacific Plate Philippine Sea Plate Philippine Sea Plate Mariana Islands Mariana Island Arc Philippines Island Arcs occur here NOT at hotspots
CONVERGENT BOUNDARY Island Arcs occur here NOT at hotspots. Trenches occur here NOT at divergent boundaries. Aleutian Island Arc (Alaska) Japan – Island Arc
CONVERGENT BOUNDARY Continental Plate Continental Plate Eurasian Plate Indian Plate = Himalayas No Subduction = No volcanoes here! Mt. Everest Mt. Everest
Other Convergent Boundaries • Check out other places in the world where there is a continent-continent collision: • Allegheny Mountains • Appalachian Mountains • Alps Note the folded mountain ranges. Note the faults. Do earthquakes happen here???
DIVERGENT BOUNDARIES Rifts and Ridges – which one is which? Check out the land near the ridge... NO TRENCHES! It is actually quite shallow! Atlantic Plate Mid-Atlantic Ridge = seafloor spreading Underwater RIDGE of new crust = volcanic rock
DIVERGENT BOUNDARIES Rifts and Ridges – which one is which? Here is an example of a RIFT Africa Another is in Iceland, where they sometimes call it a rift zone. Earthquakes happen any time the plates move relative to one another… Like here!
And what about those Transform Boundaries??? A part of fault you can see along the San Andreas • Not a lot to see here... Lots of earthquakes, faults (you can even see the cracks in some places. Earthquakes happen any time the plates move relative to one another… Like here!
HOT SPOTS – middle of plates Island CHAINS can occur at hotspots Note the long chain of extinct volcanoes…. It leads all the way back to Russia! Pacific Plate North American Plate Hawaii volcanic island chain over a hotspot – in the middle of the Pacific Plate
HOT SPOTS The MAGMA stays put. The PLATE moves!!! The rumble of the magma under the crust can cause EARTHQUAKES!
Yellowstone Hotspot • Check out Yellowstone... It is difficult to see the line of extinct volcanoes (like you can in Hawaii), but check it out!
#1) Ways Volcanoes Form on Earth • (1) Divergent Boundaries • (2) Hotspots • Convergent Boundaries with Subduction – (3) Ocean/Ocean Collision – (4) Ocean/Continent Collision
#2) Transform Boundaries have NO CHANCE of mountains or mountain ranges forming as a result.
#3) Volcanic Islands Form on Earth • (1) Hotspots • When underwater, can create island chains like in Hawaii • (2) Convergent with Subduction of Ocean Plate under another Ocean Plate • Creates Island Arcs like Japan, Mariana Islands, Philippines, Aleutian Islands
#4Earthquakes • Occur anytime plates move relative to one another. • Is used as evidence that a boundary (or hotspot) is there. • Remember the map you colored??? We used the locations of earthquakes to determine the boundaries between plates.