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Author Topic: what is lava made of?  (Read 3971 times)

paul.fr

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what is lava made of?
« on: 20/08/2007 17:51:40 »
whilst noting that neil was thinking about my topic, i began to wonder about his topic, which then prompted this question.

Just what is lava made of and are there different types. Also what is magma, is it just lava witha longer name?


 

Offline pete_inthehills

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what is lava made of?
« Reply #1 on: 20/08/2007 18:57:26 »
that would depend on the insect....oh lava not larva.  My mistake.

Magma is moulten rock under the surface and lava is moulton rock thats solidified.  Something like that.

Pete
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Offline frethack

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what is lava made of?
« Reply #2 on: 20/08/2007 19:45:03 »
Oh yeah, there are a few different types.  Probably even more than I know currently. 

The four main classes of magmas are ultramafic, mafic, intermediate, and felsic.

Ultramafic magmas are generally composed mostly of mantle material such as peridotite, and have a very low viscosity. 

Mafic magmas are high in iron, calcium, and magnesium, with a comparatively low silica content (I believe its something between 45% - 52% silica).  Both basalt and gabbro come from cooled mafic magmas, and really only differ in their crystal size (basalt cools quickly and has smaller crystals than the slow cooled gabbro.)  Mafic magmas also have a low viscosity (from low silica content).

Felsic magmas are high in silica (more than 65%), sodium, potassium, and aluminum, low in iron calcium and magnesium, and generally produce violent eruptions because of its high viscosity.  Both rhyolite (quickly cooled) and granite (slow cooled) come from felsic magmas.  The high silica comes from the melting of continental material as it makes its way to the surface.

Intermediate magmas are somewhere in between, cooling into andesite (quick cooling) and diorite (slow cooling).

There is much to be added to this, but its a start  :)

 

paul.fr

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what is lava made of?
« Reply #3 on: 20/08/2007 19:48:19 »
many thanks, frethack...again.

i just woke up this morning with geology on the mind, plus this section needed the cobwebs removing. Hopfully we will get more answers in reply to your opener.
 

Offline JimBob

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what is lava made of?
« Reply #4 on: 20/08/2007 21:40:49 »
that would depend on the insect....oh lava not larva.  My mistake.


Keep it up you could make the Illuminati sooner than you think.

frethack answered the types of lava - good job - add andesites and diorite are granites that came to the surface and it is complete.

- Pete in the hills,

Your job, should you decide to except it, is to tell us where are the different types found??? Subduction zones, hotspots, etc., etc.,

This tape will self destruct in  - oh, a while say a couple of years, is it important?


 

Offline pete_inthehills

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what is lava made of?
« Reply #5 on: 20/08/2007 22:39:14 »
all I can remember is the two hawaian names for the different types of lava

aa - spikey
pahoehoe - ropey.

the names come from what they look like.

Pete
inthehills

 

paul.fr

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what is lava made of?
« Reply #6 on: 20/08/2007 22:50:27 »
all I can remember is the two hawaian names for the different types of lava

aa - spikey
pahoehoe - ropey.

the names come from what they look like.

Pete
inthehills



i once had a girlfriend who looked a bit pahoehoe
 

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what is lava made of?
« Reply #6 on: 20/08/2007 22:50:27 »

 

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