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Author Topic: Obsidian, but no magma?  (Read 675 times)

johnnychimp

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Obsidian, but no magma?
« on: November 28, 2010, 06:30:57 pm »

So at embark I noticed a large cache of obsidian to the north, I'm trying to figure out where the magma connected to it is, but I've been looking up and down left and right but still can't find any magma. So can obsidian exist without magma nearby? Or how far away can it exist from the magma?
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BackgroundGuy

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Re: Obsidian, but no magma?
« Reply #1 on: November 28, 2010, 06:39:00 pm »

Obsidian can form a stone layer.  You probably embarked on multiple biomes, and the obsidian marks the biome boundary.
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GhostDwemer

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Re: Obsidian, but no magma?
« Reply #2 on: November 28, 2010, 07:21:29 pm »

Obsidian is an igneous extrusive stone. Igneous extrusive stone forms in areas of highest volcanism. High volcanism biomes are certainly more likely to have a magma tube, but I don't think it is a certainty. However, if you dig deep enough on any map, you will eventually hit magma in .31.x.
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johnnychimp

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Re: Obsidian, but no magma?
« Reply #3 on: November 28, 2010, 07:32:30 pm »

Obsidian is an igneous extrusive stone. Igneous extrusive stone forms in areas of highest volcanism. High volcanism biomes are certainly more likely to have a magma tube, but I don't think it is a certainty. However, if you dig deep enough on any map, you will eventually hit magma in .31.x.

Y'know I heard that, but I've had maps where I get down to Z level 0 and start getting into the negatives without ANY magma, am I just unlucky?
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Mckee

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Re: Obsidian, but no magma?
« Reply #4 on: November 28, 2010, 07:48:31 pm »

Y'know I heard that, but I've had maps where I get down to Z level 0 and start getting into the negatives without ANY magma, am I just unlucky?

The magma can be very far down, as in, below all 3 cavern layers (assuming you used 3 in world gen) and this can be a long way.
Just a tip, create a world with only one carvern layer, magma should be much closer to the surface.

As for reaching z level - 0, correct me if I'm wrong but isnt that just ground level? With all z levels below that  being -'n'
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ext0l

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Re: Obsidian, but no magma?
« Reply #5 on: November 28, 2010, 08:22:42 pm »

magma sea is usually between z= -70 to z=-90.
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johnnychimp

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Re: Obsidian, but no magma?
« Reply #6 on: November 28, 2010, 08:40:02 pm »

magma sea is usually between z= -70 to z=-90.

Oh wow I didn't even realize that it went that far down, my mistake thanks.
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Quietust

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Re: Obsidian, but no magma?
« Reply #7 on: November 28, 2010, 08:45:36 pm »

magma sea is usually between z= -70 to z=-90.

Nonsense - I've had several forts where the magma sea was above Z=100 (with ground level at around Z=140). The magma sea is only really far down when you get really unlucky and get a cavern layer than spans dozens of Z-levels.
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It's amazing how dwarves can make a stack of bones completely waterproof and magmaproof.
It's amazing how they can make an entire floodgate out of the bones of 2 cats.