While laying out land features can be fun, it’s even better when we’ve first reminded ourselves of the possibilities and what they can mean for our world’s inhabitants, our audience, and ourselves. This chapter is a roundup of the salient details world builders should consider. We can start placing items without having outlined a continent or even a coastline, but it’s often better to know where the sea is, to determine plate tectonics, covered in Chapter 3, “Creating a Continent.”
Mountains are covered first because their effect on precipitation determines the locations of forests, deserts, and rivers. We all know what a mountain is, but scholars have not agreed on a definition. What this means is that our characters can refer to something as a mountain when it isn’t that tall (less than a thousand feet), so remember this option. The land just needs to stand out from the surrounding area.
Roughly 24% of Earth’s surface is mountainous. Glaciers can create various shapes, including cirques (an amphitheater-like circle) where lakes form. If two parallel glaciers recede and carve parallel valleys, they can leave a row of peaks between them. If three glaciers recede from the same central point, a pyramid-like, sharply pointed peak or glacial horn is formed, like the Matterhorn. While these are interesting, they seldom matter on the large scale for world builders and are instead ideas for characterizing individual peaks our characters have noticed.
The highest mountain discovered in the solar system is Olympus Mons on Mars. Its extreme height (69,459 feet vs. Mount Everest’s 29,035) is due to the absence of tectonic plates on Mars. Land stays over a hot spot indefinitely, causing eruptions and lava flows in the same place, which increases local elevation. By contrast, on Earth, tectonic plates shift land (or ocean) across the hot spots, causing things like a chain of volcanic islands like Hawaii. If we want a truly enormous, standalone mountain on our world, we can decide tectonic plates don’t exist, but this would cause various changes like a potential lack of earthquakes or mountain ranges (and a resulting lack of rain shadows). Such a world might have many very tall, volcanic mountains but few if any ranges.
Such enormous mountains may not be as interesting as they sound. Olympus Mons is so wide, as big as France, that our characters wouldn’t even realize they’re on a mountain if walking on it. If we want something dramatic, than a single, solitary peak is better. Images of Mt. Shasta in California can give you inspiration. While it’s only 14,000 feet, it’s so large compared to its surroundings as to be majestic, and majesty is arguably what we’re after. We don’t need a giant Olympus Mons and its accompanying problems for our world.
Mountain ranges can have peaks formed by different forces, meaning some are volcanic while others aren’t. Several ranges can be back to back; this means one is north-to-south, and where it ends, another north-to-south range begins. To the layman, we sometimes don’t realize this; neither will our audience, but we can give two different names to a range if they’re separated by a pass or a little offset from each other. For example, the Appalachian Mountains include the Blue Ridge Mountains and White Mountains. These are regional names for the same range and are technically the smaller ranges that make up the larger one. If we have a truly long range, a thousand miles or more, it might not be realistic to say it’s a single mountain range. It’s probably several ranges.
We often speak of volcanoes as being active (they erupt regularly), dormant (it hasn’t erupted in centuries), or extinct (it hasn’t erupted in written history). These distinctions aren’t scientific and a supposedly extinct volcano can erupt again many years after the last time. By human life spans, they’re extinct, but active compared to the planet’s life span. For our purposes, these classifications work, but we can surprise our species by having a supposedly extinct volcano erupt; maybe it’s part of a prophecy.
Some volcanoes on Earth have been erupting continuously for hundreds of years, but these aren’t the explosive ones. We can have our characters believe an evil is ongoing in the world as long as Mount So-And-So is erupting. Or the reverse—a volcano’s been erupting for as long as anyone remembers and then suddenly it stops as foretold, with consequences everyone’s heard of.
A very large eruption of ash can cause a volcanic winter (when the sun is blocked out for a long time). This has caused some of the world’s worst famines and even mass extinctions.