i thought older maps had more hills and mountains
No, older maps would have more erosion and thus less hilly terrain.
Wouldn't older maps have less erosion, as there had been less time to erose?
Regardless, choosing 5 billion has more mountains/hills and choosing 3 billion has less
Here's a short code example from the ContinentsPlus.lua which says that the younger a world is, the bigger clusters of mountains in it, whereas the older it is, some of these clusters of mountains effectively turns into hills. In other words, a young world contains larger clusters of mountain ranges, an older world contains more clusters of hills.[/URL]
OK this option was never really explained that well. Just looking at the option while setting up you wouldn't even know what it did.