Dungeon Fantasy Geology

[Michael Thayne]

Some designers of fantasy worlds go to great lengths to design world maps that, while clearly not Earth, look like a possible way Earth could have turned out, if it had gotten knocked around by some asteroids slightly differently 4.5 billion years ago. That is, the coastlines and mountain ranges are different, but they appear to have been shaped by the exact same forces of plate tectonics and erosion and so on that shaped those things on the actual Earth. But this seems like a bit of an odd thing to do if you're mapping a fantasy world that did not coalesce from a nebula billions of years ago but rather was created by the gods a few thousand or at most a few billion years ago.

So what does a world shaped by fantasy forces look like? The question of how exactly the gods went about creating the Earth is a bit of a puzzle, since while they may tell their followers that faith can move mountains, few gods seem to be in the habit of moving mountains once their done with the initial creation phase of things. They seem to limit themselves to, at most, empowering their followers to move a few hundred cubic yards of rock at a time (and only then using ritual magic). Properly moving a mountain would probably take somewhere on the order of a billion FP, and it's unclear if even the gods have that much FP. This raises the question of whether the gods truly created the Earth, or whether they just tweaked it a bit after inheriting it from some even greater power. On the other hand, GURPS Magic does provide one way of making large-scale changes to the landscape: the Volcano spell. If the gods relied heavily on it when shaping the world, perhaps this should make us expect landscapes dominated by volcanos and former volcanos, and few if any other types of mountains.

Another possibility is that the world was once inhabited by a race of titans that put even the sky giants from Dungeon Fantasy Monsters 2 to shame. Humans using stone age technology have built 100 foot high mounts, so it stands to reason that SM +8 (20x human size) titans could build literal mountains (2,000 feet tall) by hand. Titans a few hundred times human size, and with no need to breathe air, might have been able to start with a perfectly spherical world covered 100% in thousands of feet of water and built from it a world with the same range of elevations as our world. However, these mountains would look noticeably different than mountains formed by geological processes, being made of loose earth or rubble rather than relatively continuous pieces of Earth's crust. Also, it would be convenient for these beings to have proportionately large trees to provide a source of wood for earth-moving tools, leading to the possibility that adventurers might find the occasional fallen (and then petrified?) log hundreds of feet thick.

Gods and giants who fall to Earth could be a source of craters, filling the role of asteroids in our world. Even a relatively "minor" event like a mile-tall titan keeling over from a heart attack could pack the punch of close to 100 kilotons of TNT (assuming the titan masses around 50 billion kilos and has a center of mass that's initially 800 meters off the ground). A god falling to earth from a greater height could have truly devastating effects.

But these are just a few ideas. I'd like to open the floor to anything people can think of.

[Turhan's Bey Company]

It just so happens that Cold Shard Mountains touches on this a bit. Legendary origins of the region aside, there are extensive networks of tunnels dug by enormous prehistoric worms (sounds a bit silly, yes, but they get a very impressive name) and bits and pieces of the landscape have been affected by magical activity, like a shallow lake formed after a great wizard casts an enormously destructive spell, leaving a crater to fill up with water.

[Dalin]

Originally Posted by Michael Thayne

few gods seem to be in the habit of moving mountains once their done with the initial creation phase of things. They seem to limit themselves to, at most, empowering their followers to move a few hundred cubic yards of rock at a time (and only then using ritual magic).

I've seen at least one instance of a moving valley. (In Cold Shard Mountains there's the Floating Valley whose occupants occasionally wake up "to find that the valley is now between different mountains."

Originally Posted by Turhan's Bey Company

It just so happens that Cold Shard Mountains touches on this a bit. Legendary origins of the region aside, there are extensive networks of tunnels dug by enormous prehistoric worms (sounds a bit silly, yes, but they get a very impressive name) and bits and pieces of the landscape have been affected by magical activity, like a shallow lake formed after a great wizard casts an enormously destructive spell, leaving a crater to fill up with water.

I love this aspect of the setting. (This is my favorite supplement in a long time.) It strikes a good balance between having fantastical elements and not being utterly alien.

[Michael Thayne]

Originally Posted by Turhan's Bey Company

It just so happens that Cold Shard Mountains touches on this a bit. Legendary origins of the region aside, there are extensive networks of tunnels dug by enormous prehistoric worms (sounds a bit silly, yes, but they get a very impressive name) and bits and pieces of the landscape have been affected by magical activity, like a shallow lake formed after a great wizard casts an enormously destructive spell, leaving a crater to fill up with water.

Originally Posted by Dalin

I've seen at least one instance of a moving valley. (In Cold Shard Mountains there's the Floating Valley whose occupants occasionally wake up "to find that the valley is now between different mountains."

I'd noticed the tunnels—an idea I love, by the way—but I'd missed some of the other details, like the crater lake and the Floating Valley. Also, when I first read the mention of the Dragon Ridge, I thought it was meant to be ambiguous whether it was really due to a dragon, but the reference to dragon ivory makes it clear that it's quite literal. And holy crap, the dragon would have been something like fifty miles long going by the map. That's around SM+28, I think? Yikes.

[clu2415]

I have an image of fantastically large saguaro cacti with immense root systems that wrong water out of their environment. The megacacti don’t grow in the desert; it’s a desert because there are megacacti.

[Michael Thayne]

Okay, some ideas:

The Fortress Vale: This is a valley inside a strange ring-shaped ridge. It's not a perfect circle, but it's much closer to being one than the vast majority of natural landforms. The ridge is higher on the inside than the outside—up to 480' outside but no more than 240' inside. The lowest part of the ridge, on the southern side, is half this tall. The only convenient ways in or out of the vale are three tunnels, apparently created by earth magic, leading out of the vale to the north, south, and east. Each tunnel is just wide enough for a heavily-laden donkey to pass. The vale is a little under eight miles across and is almost entirely good farmland, supporting about 2,000 people in total. The vale traditionally has a "king" who serves as the settlement's face in diplomatic and trade negotiations, but he rules by consensus to a much greater degree than most kings. Given the highly defensible terrain, the residents of the Fortress Vale have little use for warrior aristocrats—a lightly-armed peasant militia can easily hold the area's three narrow entrances. And there are rumors that in the past, when the militia hasn't been enough, the valley itself has come alive to defend its residents.

Mount Hell: This is an enormous dormant volcano found in the middle of a region not otherwise known for volcanism. It's nearly 12 miles across and 14,000 feet highs. Little grows on Mount Hell, and druidic magic is at -5 there, but wizards casting earth and fire spells near the summit crater do so with a +1 bonus to skill. Not that most wizards want to make the 2+ day climb for such a relatively minor benefit—the biggest impact Mount Hell has on the neighboring area is to force travelers to go around it.

The Skull Palace: Deep in the Barbarian Lands, one chieftain has chosen as his seat of power a gigantic, fossilized humanoid skull. The skull is partly buried underneath the earth, with the nearly nine-foot tall nose just above ground level, severing as an entryway. The main chamber—apparently once the titan's cranial cavity—measures 39 feet across by 51 feet long. Though not as impressive as some buildings in the great capitals of civilization, the Skull Palace makes for an impressive site compared to the small corbelled huts that qualify as "luxury" residences for most chieftans in the Barbarian Lands.

[malloyd]

Originally Posted by Michael Thayne

The vale is a little under eight miles across and is almost entirely good farmland, supporting about 2,000 people in total. .

That's a bit on the low side even for medieval agriculture - 32000 acres of *good* farmland (pi x 4^2 x 640) can probably support 5 or 6 thousand people. Cover half the ring in forest - they need a fuel source anyway - or add a small lake.

[Michael Thayne]

Originally Posted by malloyd

That's a bit on the low side even for medieval agriculture - 32000 acres of *good* farmland (pi x 4^2 x 640) can probably support 5 or 6 thousand people. Cover half the ring in forest - they need a fuel source anyway - or add a small lake.

I've struggled with finding an authoritative source on this point. All actual historical population density figures are going to partly reflect that not all land is cultivated. And in colder climates especially some portion of the land needs to be reserved for forestry so you have fire wood or charcoal in the winter. But I'm not sure what the exact numbers ought to be. I was actually envisioning the vale as part of a more mediterranean climate where they aren't going to need as much fuel in winter—but still surely some of the land should be reserved for forests, right? How much I just have no idea.

[malloyd]

Originally Posted by Michael Thayne

I've struggled with finding an authoritative source on this point. All actual historical population density figures are going to partly reflect that not all land is cultivated.

The normal range is 1 to 4 households per hyde or carucate of fields. The difficulty there is how big is a hyde (it varies but it's around 100 to 120 acres, since it's a tax unit generally the less productive the land the bigger the area), and how big is a household (presumably is averages at least 4, the current tenant and his wife and the on average two children who will live to eventually replace them). In areas where "households" were defined as extended families rather than by couples the assumption seems to have been 1 hyde would support one household, which is one of the possible original definitions - the other one being how much land a single ox team could plow in a planting season, which again given the expense of work animals you'd expect several families per team.

Modern aid agencies seem to assume 2.5 to 4 acres per person is the minimum for "subsistence" agriculture, but even the subsistence version of modern agriculture is probably more productive than a medieval farmer could reasonably hope for.

And in colder climates especially some portion of the land needs to be reserved for forestry so you have fire wood or charcoal in the winter.

It's less variable than you might think, because a lot of the fuel isn't so much for heating as for cooking. Even in tropical areas a quarter of the land near villages is usually managed woodlands - perhaps unexpectedly from a modern perspective, it's often the land closest to the houses, villages and cities are often surrounded by a belt of trees before you get to the fields. In northern Europe it is not unusual for it to approach half.

[David Johansen]

My Rolemaster campaign world is a ball of titan corpses. The titans are elemental in nature and the earth, water, and air titan corpses compose the earth and the sun is composed of the fire titan corpses. The gods themselves can be seen standing in orbit watching over the world to make sure none of the titans will gather enough energy to get up and crawl away. The humans and orcs are decay bacteria equivalents introduced by the gods, while the elves and dragons are the antibodies putting up a fierce last stand.