Volcanoes
Download
1 / 14

Volcanoes - PowerPoint PPT Presentation


  • 314 Views
  • Uploaded on

Volcanoes. Volcanic eruptions are among the Earth's most powerful and destructive forces.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Volcanoes' - garth


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  • Volcanic eruptions are among the Earth's most powerful and destructive forces.

  • Volcanoes are also creative forces. The Earth's first oceans and atmosphere formed from the gases given off by volcanoes. In turn, oceans and an atmosphere created the environment that made life possible on our planet.


Why do volcanoes erupt
Why Do Volcanoes Erupt? destructive forces.

  • Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma.

  • Magma is lighter than the solid rock around it, magma rises and collects in magma chambers.

  • Eventually some of the magma pushes through vents and fissures in the Earth's surface. A volcanic eruption occurs!


Where do volcanoes erupt
Where Do Volcanoes Erupt? destructive forces.

  • Tectonic plates float on a softer layer of rock in the Earth's mantle. As the plates move about they push together or pull apart. Most volcanoes occur near the plates boundaries.

  • Some volcanoes occur in the middle of plates at areas called hotspots- places where magma melts through the plate and erupts.


3 main types of volcanoes
3 Main Types of Volcanoes destructive forces.

  • Stratovolcanoes

  • Cinder cones

  • Shield volcanoes


Stratovolcanoes
Stratovolcanoes destructive forces.

  • Build from eruptions of lava that pile up in layers or strata (much like layers of cake and frosting)

  • These volcanoes form symmetrical cones with steep sides.


Cinder cones
Cinder cones destructive forces.

  • Build from erupting lava that breaks into small pieces as it blasts into the air.

  • As the lava pieces fall back to the ground, they cool and harden into cinders that pile up around the volcano's vent.

  • Cinder cones are very small cone-shaped volcanoes


Shield volcanoes
Shield volcanoes destructive forces.

  • Form from eruptions of flowing lava.

  • The lava spreads out and builds up volcanoes with broad, gently sloping sides.


Predicting volcanic eruptions
Predicting Volcanic Eruptions destructive forces.

  • Changes in heat flow

  • Changes in shape

  • Earthquake activity

  • Increased gas emissions and steam


http://www.pbs.org/wnet/savageearth/animations/volcanoes/main.htmlhttp://www.pbs.org/wnet/savageearth/animations/volcanoes/main.html


Why are volcanoes good
Why are volcanoes good?http://www.pbs.org/wnet/savageearth/animations/volcanoes/main.html

  • Produced our atmosphere

  • Volcanic soil is very fertile

  • Mineral resources (diamonds, copper, gold, pumice, bbq rocks)


ad