Biogeography in Fantasy

My summer reading list has included the fourth book of George R.R. Martin's Ice and Fire series, entitled A Feast for Crows.  Certain events in the story had me mulling over the map of Westeros the other day, trying to understand why Dorne has a desert environment. 

The mountain range on the west side of the kingdom of Dorne, combined with the fact that Martin mentions the winds come from the west, gave me part of the answer, as the 'rain shadow effect' (see below) would make those winds dry.  Still, Dorne has quite a bit of coast off the southwest, and it seemed to me the air masses coming from that ocean would have a lot of moisture. 

Then it occured to me -- and here was the key to the puzzle -- that Westeros is actually much larger than I've imagined it to be, extending from a polar latitude near the Wall to what is most likely to about 30N near the region of Dorne.  Roughly equivalent to the north-south expanse of Europe, from the nordic countries to Spain, with a little extra land tacked on in the south.  Some time on "A Wiki of Ice and Fire" corroborated my suspicion, and laid to rest my doubts about the capacity of Dorne to be a dry landscape. 

(My next thought was, "No wonder the royal houses of Westeros have such a hard time keeping it all under one kingdom."  I mean, really.  Why do they even try?)

One of the most challenging and interesting tasks of writing fantasy is "world building".  I was first introduced to this term by DHS, my local writers group that specializes in fantasy, horror and science fiction.  There are many, many aspects to world building, but from my point of view one must always start with the foundation:  the landscapes and biomes in which our characters live. 

It is the landscape that determines the resources available to the human (or non-human) characters in our stories.  The distribution and abundance of those resources, as well as the relative isolation of different regions, can in turn impact the structure and development of the human societies that depend upon them.

The author decides just how meticulous he or she wants (or needs) to be with the biogeographic details of a fantasy world.  But having a landscape that makes 'biogeographical sense' is one of many factors that contributes to the authenticity of a story, and whether or not your readers have conscientious knowledge of the basics of geography and climate, at some level they will sense whether the world 'feels' real or not.

When thinking about the geography and climate of your world, here are some basics to keep in mind:

 1. It's generally easier to start by assuming your world is 'earth-like' in the basics of size, rotation, relative amounts of land surface vs. water surface, distance from the sun, and so forth.  (Of course, if you are a science fiction writer, you'll probably want to throw this point out the window, as the whole premise of your story may involve a world entirely different from earth.  A wonderful example of this is Geoffrey A. Landis' award-winning short story 'The Sultan of the Clouds', set in a level of Venus' atmosphere that has more or less the equivalent of a tropical environment on earth.) 

2. Be aware of the Coriolis effect, which determines large-scale wind patterns on the earth's surface.  Because of the Coriolis effect, prevailing winds will come from different directions depending on where you are on the planet.  In the polar and tropical latitudes, prevailing winds will come from the east (northeast or southeast, depending on which side of the equator you're on).  In temperate latitudes, prevailing winds will come from the west (again, northwest or southwest, depending on which side of the equator). The interaction of landmasses, waterbodies, and wind is an important determinant of local weather patterns, so knowing where the wind is coming from (and whether it has passed over a large water body in the process of getting there) will help determine where the forests, grasslands and deserts can be found on the map of your world.

3. The interaction between the sun's energy and the earth's atmosphere leads to large-scale patterns in the distribution of forests, grasslands, deserts and polar environments, which we refer to collectively as biomes.  For example, at 30N and 30S, one can find a belt of deserts that circle the earth.  (This is the same belt that I now believe Dorne is a part of in Martin's world.)  Boreal forests, on the other hand, dominate from about 50N to 70N.  (And if you've ever wondered why there's more Boreal forest north of the equator than south of it, have a look at a map.  You'll notice our planet has a lot more land between 50N and 70N than it does between 50S and 70S. This consideration adds another level of complexity to world building.  Where are your continents and seas?  The distribution of landmasses can have a huge impact on global and local climate, and therefore the distribution of biomes.)

4. Local mountain ranges are associated with 'rain shadows', a phenomenon which causes the windward side of the range to be relatively wet, while the other side of the range tends to be dry.  In the rain shadow effect, as air masses hit mountain ranges, they rise and become cooler.  The evaporated water they carry condenses and falls as precipitation.  By the time the air mass crosses the mountain range, it has lost a lot of its moisture, resulting in dry climates on the other side.  Variation in the topography of your mountain range can add a lot of complexity to this effect.  Low passes, for example, can allow channels of moister air to reach the far side of the range.  Very high mountains can result in local air circulation patterns that lead to unusually wet slopes.  And within a mountain range, of course, there can be an interesting mix of relatively wet and dry slopes and valleys.

That's probably enough for one post.  There are many excellent on-line resources that can tell you more about how latitutude, wind patterns, land masses and water bodies interact to determine the distribution of biomes on our planet, so you can put these principles into practice when developing your fantasy world.

Next week, we'll have a look at the map of Moisehen, and talk about how these and other phenomena affect the climate and ecosystems of Eolyn's world.