By Brocken Inaglory on Wikimedia Commons

Any good fantasy setting should be true to its name: fantastic. A dash of dragons, a sprinkling of flying castles, and a few sentient forests can really improve a world’s flavor. But some stories just aren’t compatible with obvious, physics-violating quirks. You may need to stay within the realm of the plausible if you’re writing science fiction, low-magic fantasy, or – perish the thought – stuck on Earth.

Not to worry. There are plenty of quirks and eye-candy that are beyond merely plausible – they can be found on the very planet we’re currently living on.

1. Natural Nuclear Reactors

The world is permeated with a wondrous invisible energy. It’s highly dangerous, but those who devote their lives to unraveling its mysteries can harness its terrible power. In high fantasy settings, this force is magic – perhaps the gift (or curse) of an ancient god. In places like Oklo, West Africa, this force was something eerily similar: nuclear radiation. The source was not divine, yet still worthy of great respect: a critical mass of uranium in the bedrock.

Uranium ore - the natural reactors on Earth probably weren't this pretty, but yours could be.
Uranium ore – the natural reactors on Earth probably weren’t as pretty, but yours could be.

Nuclear reactors aren’t so difficult to make — if you’re not terribly concerned with maximizing efficiency, the safety of humans, or getting bombed by the American government. The reactor site at Oklo had none of these concerns; it pre-dated humanity by over a billion years, which helped. More importantly, it had just the right combination of rich uranium deposits and groundwater channels to support hundreds of thousands of years of operation. The only other place with a known reactor?  A site on Mars.

If it existed alongside humanity, the reactor would pose an insidious environmental hazard. It wouldn’t look like much, but a mysterious sickness would plague the area. The regular explosive boil-offs would be full of radioactive isotopes; essentially Old Faithful turned evil. Mighty shamans would be perplexed: their powerful magics could never remove the dark curse or banish the evil spirit from the forbidden spring.

Boring Details: Radioactive Decay

Radioactive decay of heavy isotopes, like uranium 235, is a big part of the reason the inside of the planet is so ridiculously hot. Younger worlds fresh out of the supernova are going to have an easier time setting up a reactor, and geriatric worlds orbiting old-as-the-universe red dwarf stars have essentially no opportunities for sustained fission. Even Earth can’t easily sustain natural reactors nowadays; it would require heavy water, graphite, or other, more exotic substances. The reason can be found in the very name of the process: decay implies that there’s less of the decaying substance. Specifically, 0.7% of Uranium today is the all-important fissile U235 isotope, but it was around 3% of the total while the Oklo reactor was active.

2. Drifting Islands

A movable landmass isn’t just a memorable curiosity – it can be highly plot-convenient. And spec fic writers are in luck: this quirk is perfectly realistic. In fact, sizeable floating mats of vegetation are common in marshlands the world over.  And if islands woven of reeds and forest aren’t interesting enough, our planet knows a trick for making even better ones: it burps up floating stone* from underwater volcanoes.

A pumice raft. Courtesy of the USGS and the Smithsonian Institution.
A pumice raft. Courtesy of the USGS and the Smithsonian Institution.

The largest pumice rafts can be thick enough to walk on, and they can disperse across hundreds of thousands of square miles. Pumice nuggets aren’t exactly prime real estate, though. They tend to scatter across the ocean, washing ashore on distant beaches or slowly sinking as they become bogged down with sea life.

A younger, more geologically active Earth would be pumping out pumice fast enough to form genuine (if ephemeral) floating landmasses. The Uros of Lake Titicaca have been constructing and living on floating islands made of reeds for millennia. It’s not too much of a stretch to think that humans would do the same with a readily available source of floating rock; with some simple maintenance, entire stone cities could ride the waves.

3. Burning Ice

Setting an ice cube on fire should be a red flag for magic. And it is – unless that ice happens to be a methane clathrate.

Burning Snowball: Methane Clathrate
Burning Snowball: Methane Clathrate

It makes more sense to think of clathrates as frozen vodka-cubes: normal-looking ice that’s part water, part alcohol. If its curiously combustible nature isn’t alluring enough, here’s a bonus: there are currently billions – possibly trillions – of tons of this stuff in thick layers at the bottoms of our continental shelves.* This fact is relevant to spec fic authors and petrochemical corporations alike.  (Though I have a hunch that only one of these two groups will reap billion-dollar profits and cause widespread environmental devastation by meddling with burning ice.)

A society with easy access to methane clathrates could follow a very different technological progression. Not to mention, it wouldn’t have needed to hunt whales to near-extinction for their blubber. Why light lamps with exotic whale oil when there’s cheap ice to burn?

4. Thermal Vents With Alien Life

While we’re touring the ocean floor to extract flammable ice, we should swing by the convenient neighborhood thermal vent and bask in its warm, life-rich waters.

A. D. Rogers et al. in PLoS Biology, found via Wikimedia.
A. D. Rogers et al. in PLoS Biology.

Isolated islands of chemical-powered* alien life are scattered are all across our ocean bottoms. The deep sea is a thoroughly alien place, but much of it is an empty desert, populated by scavengers fighting over scraps that drop from the surface. A source of convenient chemical energy changes this equation: the vents are crowded playgrounds of unrecognizable life.*

Now, by some strange chance your story may not be set at the bottom of the ocean. Not to worry; you can still bring aspects of this bizarre geothermal world to the surface, as anyone who has visited Yellowstone or Iceland can attest. It boils down to this: if there’s a hole in the planet, something interesting is going to be coming out – whether it’s floating bits of flash-cooled lava, nutrient-rich soup that creates an entire alien biosphere, or just plumes of water at regular intervals. Your Earth knock-off could justifiably have more of a temper, and thus more opportunities for unearthly undersea gardens populated by drow mermaids, or sacred hot springs powering dwarven mining machinery.

5. Creatures of the Sky-Abyss

Vertical relief adds character to a world, but it doesn’t exactly put you ahead of the pack. Earth boasts all manner of bizarre mountains, ridges, and canyons — readers don’t have to venture into spec fic to find these. There’s little sense of the exotic… unless you keep going down.

Weird things start happening when you drop miles below sea level, only there isn’t any sea. The modern Earth offers tiny, tantalizing glimpses of what’s possible here. The Middle East’s Dead Sea basin is only 1400 feet below sea level, yet its air is thick enough to be noticeably vitalizing. A bonus: it also blocks most UV radiation.

The Dead Sea basin is barely a scratch. The Earth has boasted genuine open-air abysses in its not-so-distant past. As recent as 5.6 million years ago, the entire Mediterranean sea was a dry, empty basin. An empty basin of oceanic crust miles below sea level. At that depth, the ridiculously rich air could support colossal flying creatures, massive insects*, and super-powered metabolisms*. Regardless of what lived there, a modern observer could only describe a trip to the Mediterranean abyss as otherworldly – and highly therapeutic, at least during the bearable winters.

An abyss in an Earth-like world populated by humanoids would be a major spa resort and salt-mining site: modern Earth’s Dead Sea on steroids. Breathing that air would feel amazing, but be warned: travelers may have to re-acclimate to ocean-level air, and civilizations of the abyss may prove weak against invading armies with stronger lungs.

…And More!

There’s plenty more real-world oddities to choose from, like log-sized crystalspermanent lightning storms, or glowing bugs that cover a cave ceiling and mimic the night sky.  If you’re a firm believer in the laws of physics or just don’t want to rely on magic, you can still build a truly bizarre setting.  Earth is already a wondrous place, and with just a few plausible extrapolations and embellishments, it can be twisted toward the truly fantastic.

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