I looked through all the other threads in this forum and didn't see anything related to it, so I thought I'd make my very first post here a tutorial.
WARNING - This tutorial gets somewhat technical
If you're anything like me (a science geek), your fantasy worlds have to be based on some degree of scientific fact, rather than total randomness. I've been working on a fantasy world for going on 13 years now, and I lost the original world map I had drawn. So I recently found myself thinking of making a new one from scratch.
Having learned about the prehistoric supercontinent, Pangea, many years ago, I thought about creating my new map by drawing a supercontinent and imagining how it would break up and form my world map. I researched previous supercontinents of Earth, such as Pangea, Laurasia, Gondwana and even older, Rodinia. Eventually, my research took me to geological basics: tectonic plates.
I then realized my method would not be in creating a fictional supercontinent and breaking it up, but by determining the existing tectonic plates of my fictional world and letting them decide what it would look like, along with a little deliberation on my part. The end result was pleasantly surprising. Now, on to the "How".
Step 1 - Drawing the Tectonic Plates
Note - please read the entire tutorial before proceeding with this step.
As a point of reference, examine the Earth's tectonic plates:
Keep this open as I'll be referring to it later in this guide.
Notice that there are 7 large, major plates and 8 small, minor plates (there are actually more minor plates, but for all intents and purposes in this guide, we'll say 8 ). Also notice that their shapes are not very erratic. There are very few inward curves.
So start by drawing a similar number of large and small plates. This is a very easy step, actually. Just as in the photo of the Earth's plates, the borders do not need to have a lot of randomness, like a coastline would. And keep in mind that the shape of the tectonic plate does not necessarily determine the shape of the continent (but it can).
The next step is to determine the direction of the plates' movement. This page shows the general movement direction of Earth's plates:
Notice that there is a mix of directions. You should try for a similar mix. These plate directions will be a large influence on the terrain of your final map, so use some deliberation here, but make a few of them random (whatever direction comes off the top of your head) to make things interesting.
Here is an example of the plates and their directions for the map I recently worked on:
Before we continue, I will need to digress and give a basic geology lesson.