2 Earth’s Major PlatesThe lithosphere is divided up into segments called platesThese plates continually move and changeMove on average of 5 cm a year (about like your fingernail)Movements are powered by unequal distributions of heat within the EarthAs they move they interact in various ways
3 Types of Plate Boundaries DivergentConvergentTransform
4 Divergent Boundaries Spreading centers Occurs when 2 plates move apart Results in upwelling of material form the mantle to create a new ocean floorExamplePart of the Mid-Atlantic Ridge emerges from the ocean & splits Iceland in half
7 Divergent BoundariesSeafloor Spreading: the process where the ocean floor is extended when 2 plates move apartOceanic Ridge: underwater mountain range created from a divergent plate boundaryTypically 1000 – 4000 km wideExample: Mid-Atlantic Ridge (runs the length of the Atlantic Ocean separating N & S American Plates from the Eurasian & African Plates
9 Divergent BoundariesRift Valley: deep faulted structure found along the axes of divergent plate boundaries.These can develop on land or on the ocean floorNarrowRuns the whole length of a mid-ocean ridge
10 Convergent Boundaries Boundary where 2 plates move togetherResults in oceanic lithosphere going beneath an overriding plate, and descending into the mantleThe India Plate pushing upward into Eurasian Plate and creating the Himalayan MountainsPlates carrying continental crust are currently moving toward each other and could one day collide and mergeBoundary that once separated the 2 plates would disappear when the 2 plates join
13 Convergent Boundaries Subduction zone: a destructive plate where oceanic crust is pushed down into the mantle under the second plateOcean-Ocean Boundary: when 2 oceanic pieces converge, 1 goes under the other. Volcanoes form under the ocean.Ocean – Continental Boundary: when the continental plate converges with an oceanic plate, the less dense continental plate floats. May cause volcanic eruptions.Continental – Continental Boundary: when an oceanic plate is subducted under the continental. A volcanic arc forms
Your consent to our cookies if you continue to use this website.