Roleplaying Resources

Creating a Realistic Map

Taken from Roleplaying Tips:

1) Mountains almost always remove moisture from the wind. This causes a “rain shadow” effect, where the side of the mountains on the trailing edge of the wind is dry, and the leading edge is moist. The wet side will have a lot of mountain rivers that transport the sponged out moisture. The dry side will also have a number of rivers that carry away moisture, but the rivers will tend to be smaller, since some of the smaller creeks and tributaries will be evaporated and/or absorbed by plants en-route.

2) Mountain ranges are created either by vulcanism or plate tectonics (or both). Sometimes a plate will subduct underneath another one causing a “crumple zone” of smaller mountains along the edge of the top plate, and about 100 miles inland a parallel chain of volcanos (extinct or not) where the descending plate's edge is melting and providing a lava source for the inner range (ala Oregon's and California's coast). Other times two plates will collide and both will crunch up (ala Tibet and the Himalayas). So I'll map out the general plates and their direction so I can see where they may be colliding or separating, and add mountain ranges as appropriate.

3) Wind can either deposit or remove moisture. It will also deposit or remove land, but this effect isn't as dramatic for determining whether or not the underlying land will become a desert or a jungle. Try to map the prevailing winds direction, their strength, and their humidity. If the winds are dry, they'll end up parching the underlying terrain. If they're wet, they'll create clouds and deposit some of that moisture, creating a temperate zone or perhaps even a jungle.

For the most part, winds will be the same direction in a hemisphere, but prevailing wind patterns can be altered by the terrain's color (whether it reflects or absorbs sunlight), height (mountains or not), and large lakes (gives a large smooth surface for the wind, and a source for moisture). Some areas will have a strong prevailing wind that doesn't fit the profile. So, this is one area where I'm a little more fast and loose. Draw in your winds, and follow the moisture wherever it goes, altering the terrain underneath as appropriate.

4) Surface features like isolated volcanoes and swamps can be caused by single source lava vents or water springs, so don't feel that you can't just plunk them about anywhere and still have a mostly reasonable world. If you have a volcano vent in the ocean, that can result in a chain of islands (Hawaii), as the plate gradually moves over the hot spot.

5) Caves are usually from limestone erosion. Areas that have a lot of limestone in the earth will tend to have large, well formed cave systems. Another source of caves is from lava tubes, but those caves tend to be rather uninteresting in gaming terms, since they're a single tube cave, rather than a system (although the tubes can be pretty long). I don't go to the trouble of mapping out the stone types in every area, but knowing that caves tend to be placed in the same region is helpful.