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Convection in the Mantle animation ations/es0805/es0805page01.cfm?chapter_no=visualizationhttp:// ations/es0805/es0805page01.cfm?chapter_no=visualization

Plate Tectonics Earth’s Lithosphere is broken into Plates Each Section Moves Plate – large pieces of crust that “float” on top of the Asthenosphere in the Mantle.

Plates move at a rate of several centimeters per year (as fast as your fingernails) Plates & Continents drift over the Earth’s surface.

2 Theories Continental Drift – All the continents were once one large “Pangea” and have slowly drifted apart about 225 million years ago 06/es0806page01.cfm?chapter_no=visualization Plate Tectonic - The Earth’s plates are in constant motion. They move because of Convection Currents in the Asthenosphere.

Convergent Boundaries Plates that collide: Continent & Continent Continent & Ocean Ocean & Ocean * One goes underneath the other * They both push up.

Convergent s0804page01.cfm?chapter_no=visualization

Active volcanoes are confined to northern Costa Rica because the subducted Cocos plate is relatively deep there. In contrast, almost no volcanic activity happens in the south because of processes directly or indirectly related to the subduction of the Cocos Ridge.

Divergent Boundary Two plates moving AWAY from each other. Causes big cracks where lava comes up and forms new land. Mountain Ridges & valleys.

Divergent Ex: Mid-Atlantic Ridge North American Plate moving away from Eurasian Plate rc/content/visualizations/es0804/es0804page0 1.cfm?chapter_no=visualization

Aerial view of the area around Thingvellir, Iceland, showing a fissure zone (in shadow) that is an on-land exposure of the Mid-Atlantic Ridge. Right of the fissure, the North American Plate is pulling westward away from the Eurasian Plate (left of fissure). This photograph encompasses the historical tourist area of Thingvellir, the site of Iceland's first parliament, called the Althing, founded around the year A.D Large building (upper center) is a hotel for visitors. (Photograph by Oddur Sigurdsson, National Energy Authority, Iceland.)

Transform Boundary Two plates slide past each other going in opposite directions Creates rifts in the Earth. Great Earthquakes. Stress from land pulling against each other & suddenly “jerk” apart.

Transform Fault fm?chapter_no=visualization Aerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range east of the city of San Luis Obispo. (Photograph by Robert E. Wallace, USGS.)

Hot Spots A hole in the plate that goes down to the Asthenosphere. Moves with the plate, leaving a volcanic island behind (Oceanic Crust)

Wahaula Visitor Center, Hawaii Volcanoes National Park, was one of more than 200 structures overrun by lava flows (foreground) from the 1983-present eruption at Kilauea Volcano. (Photograph by J.D. Griggs, USGS.)

Snow-capped 4,169-m-high Mauna Loa Volcano, Island of Hawaii, seen from the USGS Hawaiian Volcano Observatory. Built by Hawaiian hotspot volcanism, Mauna Loa -- the largest mountain in the world -- is a classic example of a shield volcano. (Photograph by Robert I. Tilling, USGS.)

Ring of Fire Area surround the Pacific Ocean. An area of volcanoes & earthquakes that ring the Pacific Plate. The Pacific Plate moves

North American Plate South American Plate Eurasian Plate Indo-Australian Plate Pacific Plate Antarctic Plate Nazca Plate African Plate Major Tectonic Plates