Today’s Agenda…  Bellringer: What are compression, tension, and shearing? Use your notes on Earth’s plates.  Quiz  Notes on Volcanoes  Homework

Volcanoes Study Pack #5

Today’s Goals…  I can explain how different types of volcanoes form.  I can describe how a volcanic eruption occurs.  I can describe the stages of a volcano.

What are volcanoes?  Weak spots in the crust where magma comes to surface, cools, and becomes cone-shaped layers of rock

Where are volcanoes located?  600 active volcanoes on land  Many more beneath the sea  Volcanoes occur in belts that extend across continents and oceans  Ring of Fire formed by many volcanoes that circle the Pacific Ocean

Ring Of Fire

Where are volcanoes located?  Volcanic belts are found along the plate boundaries  Mostly divergent plate boundaries or convergent plate boundaries where subduction occurs  Some volcanoes also occur at hot spots  An area where magma melts through the crust

Types of Volcanoes  Cinder-Cone  Composite  Shield

Cinder Cone  Steep, cone-shaped hill or mountain  Lava piles up and hardens

Cinder Cone Sunset Crater, Arizona

Composite  Form at convergent plate boundaries where one plate is pushed (or subducted) under another plate  Magma is forced up through many cracks in the crust  Sometimes explosive

Composite Mount St. Helens, Washington

Shield  Often form underwater at divergent plate boundaries  Can also form over hot spots  Lead to the formation of the Hawaiian Islands

Shield Kilauea, Hawaii

Inside a Volcano  Page 302  Magma flows from the magma chamber up the pipe  Magma flows out of the vents and becomes lava  Lava often collects in the crater and then flows down the slope  Lava hardens to form rock (igneous rock)

Stages of Volcanoes  Active – a volcano that is erupting or may erupt in the future  Dormant – a volcano that is “sleeping” but may erupt in the future  Extinct – a “dead” volcano that is unlikely to erupt again

Homework  Journey Through a Volcano Writing