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Tuesday, April 25, 2017

Volcanoes

Sthelensharrytruman
Volcanoes are of legend and fascination in their unpredictable and explosive power. I remember the headlines of the eruption of Mt. St. Helen in 1980.. There was video of a car hurtling as fast down the road trying to outrace the volcanic cloud raining down. There was the elderly man, Harry Truman, who refused to leave his home and never found again. We all read the newspapers fascinated.

Archaeologist have unearthed history from the explosion of Vesuvius in 79 AD.

There are two sorts of lava flows. The Hawaiian Islands have shield volcanoes. Scientist and people can stand beside calm lava flows. Native Hawaiians taught people to walk across the active volcano at night. The heat of the red embers were visible at that time.

Shield volcanoes have basaltic lava which has no quartz and no water. It's calm flows continue to flow as the outside hardens which produces a tunnel. These tunnels can fill with ocean water that pipes up sprays of ocean water from the force of incoming waves or have lush entrances of plants on land.
Entrance Thurston Lava Tube



Explosive volcanoes have lighter granitic lava which contains water. The water becomes an explosive gas which expels lava out of the volcanic opening.




Mt St Helens Eruption March 8, 2005
Mt. St. Helen's eruption in 2005     

2 comments:

  1. Hi Ann - the Mount St Helen's eruption was quite extraordinary to see played out in the media. Volcanoes are as interesting as the earth itself ... we are learning more - but it all takes time and scientific research. The history around Vesuvius and Pompeii and Herculaneum is totally absorbing, especially now when so much can be found out ... cheers Hilary

    http://positiveletters.blogspot.co.uk/2017/04/v-is-for-vaynol-cattle.html

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  2. Sometimes it seems hard to believe that a volcano erupted in the continental US. Hopefully there won't be another like that any time soon.

    V is for Vaxxed, the movie

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