Some Help

[Hoel]

It is possible under very exceptional circumstances... like magic

[Karro]

Underground lakes are certainly possible, under very earthlike and non-magically-influenced conditions as well.

Underground Lake and here.

Not only that, it appears possible for the water system in such a cave network to feed surface water.

Now, underground seas... (they'd be freshwater seas, most likely, due to the nature of ground water) that might take a bit more magic to make it happen, but since the rudiments are already there, I don't see it as outside the realm of believability.

[jfrazierjr]

Not quite sure the difference, but there is an "aquifer" which is under the midwest and spans like 10 or so states, so that it is easily as large as some of the larger above ground inland seas. I can't remember the name of it, but someone had a link about it here a month or so ago (NK perhaps?) in another topic.

[Karro]

Not quite sure the difference, but there is an "aquifer" which is under the midwest and spans like 10 or so states, so that it is easily as large as some of the larger above ground inland seas. I can't remember the name of it, but someone had a link about it here a month or so ago (NK perhaps?) in another topic.

Aquifers, as I understand it, flow through the ground itself, usually flowing through sedimentary or porous layers of rock or ground and trapped in between denser layers of rocky material.

I would think, theoretically, that if an aquifer ran into a large, cavernous hole in the porous and upper-rocky material (while still being trapped on the lower bound up by dense rocky material) that it would expand to fill the cavernous space, thus creating an underground freshwater sea.

[crackerjake]

Ah, this is good news. Now I can have my river border!


But still, would it be logical to think that an underground river would run from this underground body of water and surface as a spring, which, in turn, flows out to the sea as another river?

[Hoel]

Yes. It would be possible, but the river would probably only have one outlet, either the underground or the spring.
But with magic who can say?

[Midgardsormr]

Yep. At some point, your terrain level will drop below the surface level of your underground water source. At that point, a spring will form, which will take the water out to sea.

Incidentally, this particular kind of formation is one of the rare exceptions to the non-forking water source rule. An aquifer can feed more than one spring because there is an upper limit on how much water a given spring can carry.

[Ascension]

I can't really help with the science stuff but from personal experience I have a lil snippet. In college (Mizzou) there was a cave we used to hang out at called "Devil's Icebox" (because it was cold). We'd turn out the lights and let the bats fly by our heads...kind of cool really. The cave was formed by an underground stream and we would canoe it for a while and then it came to a wall where we needed scuba gear to go further (it goes on for another 21 miles like that). We had no idea where to get scuba gear in the middle of Missouri so we just trusted the map that was provided.

[crackerjake]

Hmm, I've just thought up of something else. How big does a spring have to be before it turns into a pond? I was thinking about how ridiculous it would be for a large river to have its source at a small spring. I suppose I could have multiple springs with streams that unify into one river...but then that'd bring up the question of a river having more than one spring.

So my questions now are:

1) How big does a spring have to be before it becomes a pond
2) Is it possible for one of these underground rivers to have multiple springs


Aaaah, nevermind, ignore #2, because that'd go back to the whole irregular river splitting thing. Grrr, making a new world is more complicated than I thought it would be

[Ascension]

If the springs all share the same water table then I don't see a problem, EDG might be able to better answer this one.