Geology

[Superfluous Crow]

In line with the current poll, i was wondering whether anyone could sketch up some of the rules concerning geography and maps? The only two i can currently come up with is that mountains appear where continental plates meet and that deserts can appear in the cover of mountains (since the mountains supposedly absorb the humidity of the wind).

[Raelifin]

I'm not an expert by far, but my studies have produced the following guidelines which I use heavily.

Tectonic plates are the primary cause of land-masses vs. ocean. Some plates are taller than others, which causes continental shelf.
* Each plate has a drift, and where plates drift together or apart, there is a zone of change.
* Zones of tectonic change are what produce earthquakes, volcanoes and mountains. There are specifics about each.
* Wind and water have specific direction which is more or less constant. These are currents.
* Water acts a heat buffer. Coastal regions will have a much more even temperature than an inland one, as the sea will act almost like insulation.
* Wind directs rain patterns. Wherever rainclouds travel, precipitation occurs.
* Most precipitation happens when clouds go up in elevation (mountains). Rain and snow on mountains is what causes most rivers and lakes.
* Deserts are formed where wet-clouds cannot reach, either by large amounts of land, mountains, or even winds blowing in the wrong direction.
* Due to planetary spin, winds at the equator tend to blow east-west and be more powerful than other winds. These are the trade winds.
* If your moon is like earth's, the tidal strength depends on latitude. The further away from the equator you are, the stronger the waves will be.
* Storms typically form where different wind channels meet.
* I'm sure pressure factors in, but I don't know how.
* Tides and winds from a colder region will bring cold, and vice-versa.

That's all I can think of atm. Hope it helps.
 - Raelifin

[Raelifin]

Oh, and it's easy to forget latitude. Don't put tropical regions in temperate zones or cold regions at the equator. (Duh)

[sparkletwist]

If your map needs a bit of tweaking, you can get away with some pretty cold areas in otherwise tropical latitudes provided you put them at high altitude. :)

[Hibou]

I'm pretty sure I read somewhere too that many rivers and lakes  can't exist by precipitation alone, and are fed by underground water sources.

[Pellanor]

Tectonic plates are the primary cause of land-masses vs. ocean. Some plates are taller than others, which causes continental shelf.
* Each plate has a drift, and where plates drift together or apart, there is a zone of change.
* Zones of tectonic change are what produce earthquakes, volcanoes and mountains. There are specifics about each.
* Due to planetary spin, winds at the equator tend to blow east-west and be more powerful than other winds. These are the trade winds.

While you hit on a lot of good ideas, these are a couple that I need to comment on.

The first three points work assuming your planet has earth like tectonic plates. Not all planets do, Venus being an example of a planet without plate tectonics.

The last point also assumes that your planet rotates in the same direction as earth. The east-est winds would be reversed if the planet spun in the opposite direction (like Venus).

In addition, if you're making any major changes to your planet (ie, planetary rings, multiple moons, no moon, etc...) try to take into account how those changes might affect your planet. It can be quite difficult, but doing that extra bit of work can add that bit extra to your world.

[Raelifin]

Correct. However, a non-earthlike planet is a big project and probably not in the scope of the question presented.

I didn't know about Venus lacking tectonics. That's cool.

 - Rael

[Superfluous Crow]

It is times like this that i regret i made my world flat... well, i just have to make the best of it i guess.  :)
What effect would planetary rings and extra moons have?
And how is it winds work again? It has been a while since i last looked into that.
And if anybody knows of a good link to any pages concerning this, you know what you must do.

[Ishmayl-Retired]

I don't know if all the links are still good, but this page used to be an excellent source for world building information.