Lets Build a World: Part Ten: World Mapping and Tectonics

After a long break we are back to the world building process with The World Builder’s Guidebook (AD&D 2ed). We have come to the slowest part of the process – maps.

The book came with a pad of blank maps to use, as this was in the days before mapping software was really an option. The expectation was that it would all be done by hand. For the world map, they provided a polyhedral map, as seen below. The world was split into 20 sections, as we previously rolled for, and you assigned the various sections based on the continents you had rolled up.

While it does make for a more realistic global map, not all worlds are necessary global, and if you are using other means to map, such as mapping software, they may not always have the option to be polyhedral.

So for this I am going with a more standard looking map. We place the two continents we rolled in squares 4 and 7 and then assign the rest of the options were we want. The end result looks like this.

That is, of course, the easy bit. Now we have to sketch out the shape of the world based on what we have. Half land/half water is what is says, while major islands have around 25% land and 75% water. Minor islands have a scattering of land, maybe 5%, while water is pretty much just water, with maybe a small island here or there. On a piece of paper I map out a rough design of the world, as show here.

With an idea of how the world works, we come to the next stage, the seismology and tectonics of the world. This, of course, is based on the concept that your world is similar to Earth. You may not need to worry about this step if you are going for something wild and unusual, but for this example we are going to keep following the book.

A Earth-sized world has 4d4 plates, each of 1d6 regions. Our roll is 11 plates, so we start to roll to see how many regions each has. We start rolling with 6, 2, 2 and 5. That brings us up to 15 regions already, leaving just 5 left. As we have rolled more plates than that, we just add 5 more of 1 region each and drop the last 2. It may be that you end up with not enough regions, in which case you can just add the left over region to the last plate.

Now we have the plates we need to add them to the map. Generally along the boundary between land and sea, or along island chains is a good place to put then, though they don’t necessarily have to follow that; looking at Earth’s plates you can see one running right down the middle of the Atlantic. One to three plates per ocean basin or continent is recommended. The red lines on the map below are how I allocated them.

So what are the rest of the markings on the map about? Well, where plates meet is a good place to find mountains and rifts as well as volcanic and seismic activity. Plates meet each other in one of three ways; away from each other, towards each other or alongside each other. Starting with one plate, you roll on the plate movement table to see in which way they are moving (and from that you know what the other side is doing), and see what it causes. Plates moving towards each other tend to make the largest mountains, while those moving alongside each other will result in seismic activity.

The red arrows on the map indicate the movement of the plates. As can be seen I didn’t fill them all in; you can if you want, but it isn’t required. The blue lines mark deep ocean trenches, forming where one plate is sliding underneath its neighbor. The brown lines mark mountain chains; 1 line for low mountains, 2 lines for medium mountains and 3 lines for high mountains. In this case the ‘mountains’ are submarine ridges that the peaks of form island chains.

World size can play a part in adjusting the size of mountains, if you wish for that. World’s smaller than average adjust mountain ranges up in size, while larger world’s than Earth adjust it down.

Volcanic chains are also marked on the map. The solid orange triangles active volcanoes, the solid yellow triangles are dormant volcanoes and the hollow orange triangles are extinct. Given that one of the most important deities in the pantheon of the world is the Lord of Volcanoes, these are liable to be important places.

I haven’t marked down anything about earthquakes, but will keep an eye on any regions that might experience them as we further explore the world.

Of course, if you are going with a fantastical world and don’t want tectonic plates, you can roll on a sperate chart to place mountains per region, ranging from normal mountains to fantastical ones, like ones that are gates to elemental plains.

Next time we move on to the climatology of the planet.

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