The Story of Plate Tectonics November 12, 2013

Last Week We Learned Continental Drift Why plate tectonics move – convection cells (like a lava lamp) Think back to density

Convection Cells in the Mantle Lithosphere: the solid outer layer of the Earth that consists of the crust and the rigid (unable to bend) upper part of the mantle Asthenosphere: the solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly and allows tectonic plates to move on top of it Play movie at 3:57

Page 5 of ESRT

There are four types of plate boundaries: 1. Divergent boundaries -- where new crust is generated as the plates pull away from each other. 2. Convergent boundaries -- where crust is destroyed as one plate dives under another. 3. Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other 4. Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear 2. Convergent boundaries -- where crust is destroyed as one plate dives under another. 3. Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other. 4. Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear

Divergent Plate Boundaries

The Mid-Atlantic Ridge, which splits nearly the entire Atlantic Ocean north to south, is probably the best-known and most-studied example of a divergent-plate boundary.The Mid-Atlantic Ridge, which splits nearly the entire Atlantic Ocean north to south, is probably the best-known and most-studied example of a divergent-plate boundary.

Convergent Plate Boundaries 3 Types of Convergent Boundaries Ocean to Continent Ocean to Ocean Continent to Continent

The convergence of the Nazca and South American Plates has deformed and pushed up limestone strata to form towering peaks of the AndesThe convergence of the Nazca and South American Plates has deformed and pushed up limestone strata to form towering peaks of the Andes

The 6,000- km-plus journey of the India landmass (Indian Plate) before its collision with Asia (Eurasian Plate) about 40 to 50 million years agoThe 6,000- km-plus journey of the India landmass (Indian Plate) before its collision with Asia (Eurasian Plate) about 40 to 50 million years ago

Transform Boundaries

The Blanco, Mendocino, Murray, and Molokai fracture zones are some of the many fracture zones (transform faults) that scar the ocean floor and offset ridgesThe Blanco, Mendocino, Murray, and Molokai fracture zones are some of the many fracture zones (transform faults) that scar the ocean floor and offset ridges

The San Andreas fault zone, which is about 1,300 km long and in places tens of kilometers wide, slices through two thirds of the length of California. Along it, the Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of about 5 cm/yrThe San Andreas fault zone, which is about 1,300 km long and in places tens of kilometers wide, slices through two thirds of the length of California. Along it, the Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of about 5 cm/yr

Hotspots Regions of earthquake and volcanic activity which do not occur along plate boundaries

The vast majority of earthquakes and volcanic eruptions occur near plate boundaries, but there are some exceptionsThe vast majority of earthquakes and volcanic eruptions occur near plate boundaries, but there are some exceptions

Map of part of the Pacific basin showing the volcanic trail of the Hawaiian hotspot-- 6,000-km-long Hawaiian Ridge- Emperor Seamounts chainMap of part of the Pacific basin showing the volcanic trail of the Hawaiian hotspot-- 6,000-km-long Hawaiian Ridge- Emperor Seamounts chain