Plate Tectonics the movement of Earth

Tectonic Plates Earth’s lithosphere is broken into about 19 pieces These plates move on top of the asthenosphere

Plate Boundaries Places where the plates meet

Types of Plate Boundaries Transform Fault Boundaries –(Sliding) Divergent Moving apart / Rifting Convergent Colliding / Sub-duction

Transform Fault Boundaries Faults form when plates slide past each other A fault is a large crack in rocks that can break EARTHQUAKES can happen along fault lines

San Andreas Fault, CA

Divergent Boundaries Boundary between two plates that are moving apart or rifting   RIFTING causes SEAFLOOR SPREADING

Divergent Plate Movement: Seafloor Spreading the movement of two oceanic plates away from each other (at a divergent plate boundary), which results in the formation of new oceanic crust (from magma that comes from within the Earth's mantle) along a mid-ocean ridge. Ocean floor spreading was first suggested by Harry Hess and Robert Dietz in the 1960's.

Features of Divergent Boundaries Mid-ocean ridges

Features of Divergent Boundaries Rift valleys Quilotoa, Ecuador

Features of Divergent Boundaries Fissure volcanoes Hawaii, USA

Convergent Boundaries Boundaries between two plates that are colliding   Different things can happen, depending on the density of the plates involved. There are 3 types…

Oceanic-Continental Ocean plate colliding with a less dense continental plate Subduction Zone: where the less dense plate slides under the more dense plate VOLCANOES occur at subduction zones

Andes Mountains, South America

Oceanic-Oceanic Ocean plate colliding with another ocean plate The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH

Two Oceanic Plates - When two oceanic plates collide, one may be pushed under the other and magma from the mantle rises, forming volcanoes in the vicinity

Aleutian Islands, Alaska

Continental-Continental A continental plate colliding with another continental plate Have Collision Zones: a place where folded and thrust faulted mountains form.

Two Continental Plates - When two continental plates collide, mountain ranges are created as the colliding crust is compressed and pushed upwards.

Fold: When rocks bend Anticline (Upward) Syncline (Downward)

Causes of Plate Tectonics

Convection Currents Hot magma in the Earth moves toward the surface, cools, then sinks again. This circulation of heat creates convection currents. Convection currents beneath the plates cause the plates to move.