Doesn't the fact that there's an undervault as expansive as the one we have preclude the idea that it's a caldera? (<--- didn't do geography past year 9 so not sure)

Solid rock, you mean?

Having an extensive network of tunnels and caverns is actually probably a pretty good sign of past volcanic activity. if nothing else. Magma doesn't always simmer all through a volcano, close to the surface, afaik, only when it's close to erupting.

Still would mean there has been volcanic activity in the past.

From the Undervault.

There is also lava in the Newton Caverns, and by the Serpent Skull.

If its an extinct volcano, then there wouldn't be any magma left in the undervault as it would have crystallized into igneous rock. What we will have to do is decide what the origins of the rock in the undervault is. If the rock is granular, then it will be sedimentary rock, and not volcanic, in which case the basin is a... ...sedimentary basin. If it is crystalline then it will be either igneous or metamorphic, or both. If there is both igneous and metamorphic rock, the igneous rock could be the remains of the magma chamber, and the metamorphic rock the surrounding rock that was metamorphosed by the intense heat of the magma chamber. If there is no igneous rock, and mostly metamorphic rock than it is more likely to be an impact crater.

As for Mount Zoaka, it is close to the ocean, so if we discover a large trench off the coast of the desert, it is possible there is subductive plate margin (assuming such things as continental drift exist in Lusternia), and the subduction of the oceanic plate under the continental plate is causing the vulcanism of Mount Zoaka. Which may or may not be related to any past vulcanism involving the entire basin.

I could go on and on like this...but I'm sure you don't want a geology lecture.


EDIT: Yeah, or Caffrey could prove there is a vast and still active magma chamber in the undervault, in which case I go with the volcano theory.

EDIT 2: Wait, where is that room? If its in the south-west undervault it could be Mount Zoaka's chamber.

The plate tectonics theory is plausable, the major volcanic activity is occuring in the mountains around the edges, so the Basin could be one tectonic plate with multiple subduction zones around it. This would also explain the mountains.

However, the fact we have such a vast network of tunnels, and large cavern under the centre, makes me think the cavern for the Sea of Keph is infact the old magma chamber of a very large volcano.



It's NWish, I'd guestimate it to be underneath the land between Serenwilde and Celest.

I didn't mean that...sides, continental plate doesn't subduct under other continental plate. I was just talking bout Zoaka's current vulcansim.



I think you're right. But I die 5 minutes after I enter the undervault, so I can't go spelunking.



WHAT? That terrible!

So all Mag and Glom need to do is make it erupt and the problem of the 'wilde and Celest's existence is solved.

You might not have meant that, but what you said about Zoaka holds true for the rest of lusternia, as we do appear from the graphical map (some bits are off the map) to be surrounded by water. So we may well be a continental plate surrounded by oceanic plates.

Edit: Also, IANAG, but I thought you could have subduction zones with continental-to-continental plate boundaries.

I thought it was all land to the northwest of us, but you do know Lusternia's geography better than I do. *peers at map* Oh, there's a small bit of water up there....I never saw that before. So, supervolcanic island in the middle of an ocean?

Looking at places on earth where two continental plates have collided, you'll see that they pile up into large mountain ranges instead of one subducting under the other. Himalayas, the Alps. Or slide past each other like California. As far as I know the crustal composition makes it too light to be forced back into the mantle.

I'll go climb Mount Seriode.

It looks more to me like an impact crater than a volcano. There's certainly a lot of similarities, but it seems to me an impact crater is a much more likely explanation, because of the lack of a significant elevation difference between outside (Skarch, most prominently) and inside, and the descriptions of the mountains. The size also suggests a crater more than a volcano; though everything on Lusternia is bigger than life, it's still a more Occam-compatible explanation. Plus Spectre Isle is in just about the right place to be the central peak uplift.

In fact, when I read the last book of the Elder Wars, when Keph and Illith smashed into Lusternia, I wondered if that's not what formed it. (Didn't care enough to actually check if there weren't already signs of that shape before that point, though.)

Nothing about an impact crater precludes the existence of volcanic activity in the same area, of course. (Nor does it contraindicate the Undervault.)



Learn about impact craters

Well, the only problem with the impact crater theory is that it seems the mountains are the same height on both sides, while that crater in your picture has mountains that are very steep into the crater, but only got pushed up a bit on the outer sides. The only place where it doesn't seem to have that massive elevation is that small gap in the mountains where there's an opening out to the Skarch (that you mentioned). You have to climb way up on both sides to get back onto the mountain paths.

It seems to make a bit more sense as a site of volcanic activity-- a massive, massive one. A number of the underground tunnels could very easily be lava tubes, and some of them could have been created / widened by a few various Gods pushing through tight quarters.

One thing not answered is how far down the undervault is. We only know the game as "rooms", so how far down is it? It could be many miles down, which might make lava possible down there without the basin having to been formed from a volcanic eruption.

Ahhh the chubby god theory of lava-tube widening. Illith had a bit too much Elder-Pie?

A volcanic caldera would almost certainly have the mountains far higher on the outside than the inside, but impact craters are perfectly capable of having a much smaller difference in internal and external elevation. That's actually another point in favor of the impact crater theory. For example, Mons Olympus is 3km deep on the inside, 27km high on the outside. Mauna Loa's caldera is 60m deep, but the volcano itself is 4km high on the outside (10km if you measure from its true roots at the bottom of the Pacific). I think you'll be hard-pressed to find a volcano whose external height is less than 20x higher than its internal height, and most are hundreds of times higher.

Odds are there's no right answer. The designers probably just picked the desired shape, and similarity to real geological structures derives from their familiarity with same. (Though if there's any MUD with an original world that did have a real answer, it's probably Lusternia.)

Silly undervault. Totally messed up my story I was writing about about a guy who goes to visit the incredibly deep underground tunnels of the Great Spirit of Groundhog and his followers who look after the deep roots of the Great Trees.

Anyway, I started thinking of Keph and Illith's battle...



Their battle must have torn up the underground of Lusternia, maybe enough to cause a supervolcano to form?

Well, if you really think about it in-depth, it's pretty obvious that the impact theory / volcano theory both had to be something that occurred *before* the Elder Wars. Simply read through all of the previous Elder War books. There are too many landmarks, easily recognizable things, that would just not exist if a volcano had erupted or if something huge had formed that crater afterwards. The Basin had to have already been formed beforehand (or there's a huge hole right through the middle of the Histories).

If you take that theory, then you have Viravain, Shikari, etc. going through the tunnels to find Keph (tunnels which also already existed, though they were very small for the Divine).

I notice it says in the Book of Orlachmar that "Illith the Leviathan had entered the oceans and disappeared deep into the surface. We suspected she was going to try to break the core of the world."

If the basin was already an area of great geological activity then the crust would be weak and thin, and a perfect place for Illith to try to break through to reach the core. Only Estarra knows what damage Illith did to the already fragile crust! We could be on the verge of a huge volcanic eruption!

(what, no "the end is nigh" smiley?)

There were LOTS of battles though, both the Elder and Vernal wars, which could be Aeons old. I doubt we can use one event to determine current geological conditions.

And regarding your sig--when did Ialie join the X-Men?!

Something else I've always wondered: how big is a "room"? In Achaean fishing, you could cast your line about 80 ft into another room, so rough estimate of about 100 ft being the length of a "room"?

I don't think there is a set size for a 'room'.