Plate Boundaries Plate Boundaries Why do we care

Plate Boundaries

Plate Boundaries �Why do we care about plate boundaries?

Plate Boundaries �Volcanoes and earthquakes most often occur where tectonic plates come together. �At plate boundaries, many other geologic features, such as mountains and rift valleys, can also occur.

Plate Boundaries �There are three basic types of plate boundaries: 1. Divergent 2. Convergent 3. Transform Fault Boundary

Divergent Boundary �A divergent boundary occurs where two plates move apart and create a gap between them.

Divergent Boundary �Hot rock rises from asthenosphere and cools to form new lithospheric rock. �Diverging plates then pull newly formed lithosphere away from gap. �New lithospheric (oceanic crust) is formed.

Divergent Boundary �Mid-oceanic ridges are mountain ranges at divergent boundaries in oceanic crust.

Divergent Boundary �Real Life Example: Mid -Atlantic Ridge �Mid-Atlantic Ridge runs through Atlantic Ocean from Arctic Ocean to an area off the southern tip of South America.

Convergent Boundary �A convergent boundary occurs where two plates move toward one another.

Convergent Boundaries �There are two types of convergent boundaries: 1. Subduction 2. Collision

Convergent Boundary - Subduction �Subduction is the process by which one lithospheric plate moves beneath another plate.

Convergent Boundary - Subduction �Ocean – Ocean �Two oceanic plates collide �Generates volcanoes �Generates island chains �Real World Example Japan

Convergent Boundary - Subduction �Ocean – Continent � Oceanic and continental plate collide � A thin, dense oceanic plate collides with a relatively light, thick continental plate, the oceanic plate is forced under the continental plate � Real World Example Andes Mountains

Convergent Boundary - Collision �Continental – Continental �Two continental plates collide �Real World Example Himalayas

Transform Fault Boundary �A transform fault boundary occurs where two plates slide past one another.

Transform Fault Boundary �Plate movement at transform fault boundaries is one cause of earthquakes. �Real World Example San Andreas Fault

�http: //www. wwnorton. com/college/geo/egeo/anima tions/ch 2. htm �http: //www. classzone. com/books/earth_science/ter c/content/visualizations/es 0804 page 01. cfm ? chapter_no=08