Get Ready for an ERUPTION!!!

 Three Types of Volcanos  Shield  Cinder Cone  Composite

 Shield Volcano  Created by hot

spots  Gently sloping

 Cinder Volcano  Steep  Cone-shaped hill/

mountain Composite Volcano

Tall, cone-shaped mountain Alternating layers of ash and lava

http://www.earthonlinemedia.com/images/lithosphere/volcanism/shield_volcano_2.gif

http://www.earthonlinemedia.com/images/lithosphere/volcanism/shield_volcano_2.gif

Ecuador volcanoes, Guagua Pichincha volcano

Ash cinder and bombs erupt explosively to form a cone shaped

hill http://www.youtube.com/watch?v=aS_xl3nu_mY&NR=1&feature=endscreen

http://www.youtube.com/watch?v=1u1Ys4m5zY4

Quiet eruptions alternate with explosive forming layers of lava ash.

http://facweb.stvincent.edu/academics/pathways/science/volcanoes.htm

 A weak spot in the crust where molten material, or magma, comes to the surface

 Magma- molten mixture of rock-forming substances, gases & water from the mantle

 Lava- Magma that reaches the surface

 Volcanoes can be found:  Diverging Plate boundaries

  (mid-ocean ridge)

 Converging plates with subduction zones  Oceanic plate vs. oceanic plate  Oceanic Plate vs. Continental plate

 Hot Spots  Area where magma from deep within the mantle

melts through the crust like a blow torch  Example: Hawaiian Islands

 Ring of Fire

 A circular pattern located around the pacific ocean along the plate boundaries where volcanoes are more common

 Are constructive:  add new rock to existing land   form new islands

 Can be destructive  explosive eruptions changes the

landscape of and around the volcano

 Why do volcanoes erupt?  Less dense magma seeps upward through

cracks and creates volcanoes  Gas in the magma is trapped and builds

pressure  Closer it gets to surface the less pressure it

has and the gases separate (bubbles)  Gases dissolve on the surface and magma is

carried out

 2 types:  Quiet

 Lava moves steadily and easily

 Explosive  Thick, sticky lava plugs vent like a cork and

builds up pressure  Explodes and releases pyroclastic flow

 Volcanic ash: fine, rock particles  Cinders: pebble sized particles  Bombs: baseball to car sized particles

 Shield Volcano  Created by hot spots  Gently sloping

 Cinder Volcano  Steep  Cone-shaped hill/mountain

 Composite Volcano  Tall, cone-shaped mountain  Alternating layers of ash and lava

http://www.earthonlinemedia.com/images/lithosphere/volcanism/shield_volcano_2.gif

Ecuador volcanoes, Guagua Pichincha volcano

Ash cinder and bombs erupt explosively to form a cone shaped

hill http://www.youtube.com/watch?v=aS_xl3nu_mY&NR=1&feature=endscreen

http://www.youtube.com/watch?v=1u1Ys4m5zY4

Quiet eruptions alternate with explosive forming layers of lava ash.

http://facweb.stvincent.edu/academics/pathways/science/volcanoes.htm

 Volcanoes can be found:  Diverging Plate boundaries (mid-ocean ridge)  Converging plates with subduction zones

 Oceanic plate vs. oceanic plate

 Hot Spots  Area where magma from deep within the mantle

melts through the crust like a blow torch  Example: Hawaiian Islands

 Type of lava produces different types of rocks

 Slower Flowing, Thicker, sticky, lighter colored

 Rhyolite, Pumice, obsidian  flows readily, dark colored

 basalt

 High Silica –  thicker, sticky, lighter colored

 Rhyolite, Pumice, Obsidian

 Low silica lava   flows readily, dark colored

 Basalt

 Quiet vs. Explosive – determined by

 Percentage (amount) of silica (material made from the elements oxygen and silicon)

 Active: (live) erupting or has shown signs that it may erupt In the near future

 Dormant: (Sleeping) is not currently erupting but may/can erupt in the future

 Extinct: (dead) unlikely to erupt again

 Hot springs  Groundwater is

heated by near by magma rising to the surface and collects in natural pools

 Geyser  Rising hot water

and steam that gets trapped underground and builds pressure until it sprays to the surface

  http://w4.nkcsd.k12.mo.us/~mkurbin/ptrevgms.htm

 Lava Plateaus  Lava moves far from the volcano before

cooling which forms high plateaus

 Calderas  Huge hole left by the collapse of a volcanic

mountain  All magma has been emptied leaving a hollow

shell that collapses

 Volcanic Neck: magma hardens in the volcanoes pipes and the soft rock wears away

 Dike: magma that was forced across rock layers hardens and the soft rock wears away

 Sill: magma that squeezed between rock layers hardens and the soft rock wears away

 Batholith  Mass of rock formed when a large body of

magma cools in the crust

 Dome Mountains  Rising magma is blocked by horizontal rock

layers and forces the rock layers to bend upward into a dome shape and then the soft rock wears away

  TYPES   -- Shield - layers of lava- gradual hill - quiet   -- Composite – Quiet/Explosive – layers ash and lava   -- Cinder Cone – Quick Formation - Explosive

  LOCATION (s)   -- Hot Spots   -- Ring of Fire (Convergent Boundary)   -- Divergent Boundary (MOR-Mid Oceanic Ridge)   --Island Arc (Convergent oceanic oceanic boundary)

  ROCKS FORMED/LAVA FLOW   -- Pyroclastic Flow – Cinder, Ash, Rock, Pumice, gases   -- Pahoehoe – fast – low silica- low viscosity   -- Aa – slow moving, high silica – high viscosity   -- Pumice – Light and airy- from explosive eruptions   -- Obsidian – more dense and smooth   -- Basalt – low silica lava flow

 FLOW & What determines it?  --

 --  --

 --  --

 PARTS OF A VOLCANO  --  --  --  --  --  --  --