Maps!
I have a terrible confession to make. I don’t care for maps at the beginning of books. It’s like F do I care whether this made-up country is north or south of this OTHER made up country. I’m not going to remember those city names after I finish reading, I hope you know that. And you didn’t even get the plate tectonics right.
But it turns out that in some circumstances maps are necessary for the author if for no-one else, as I realized when I tried to plot out a book about people hiking through various alien biomes. I really really had to know where all the biomes were in relation to each other and the hikers’ goal.
So I cheated:

Look familiar?
I knew I wanted to base this story loosely on the Lewis and Clark Expedition, specifically in their crossing of the Lolo Pass, so what better place to start than the Lolo Pass itself?

Not a bad likeness
The result is something that seems to work hyrdo-geologically and fulfills all the plot points of my story. Once again:
X’s indicated known or presumed wormholes. Arrows indicate rivers. Prevailing winds are from the Northwest.
The story begins at point A, where the wormhole to Earth is situated. Generations of native humans have extended the Earth Biome to the southern tip of a valley. Terraforming has been harder going to the north, where the rivers bring foreign organic material from several wormholes. The Wormtree Biome is the most vexing current problem.
Our heroes fly directly east from the settlement around the Earth Wormhole, over two mountain ranges and the Continental Divide, before their plane crashes, stranding them in the Diatom Biome. Their hike back east includes six alien biomes, monster-fighting, explosions, mountain-climbing, hunting, being hunted, sex, murder, white-water rafting, intrigue, espionage, international exo-geopolitics, terrorism, robots, and The Bomb in more-or-less that order. Try to guess where they fit on the map!
