Requesting help with campaign world geography

[Seharvepernfan]

Hello, I am creating a new campaign world from scratch, and there are a few things I can't figure out on my own, and some other things I would like to hear your opinions on.

First, my campaign world is a relatively recently split supercontinent. It is like earth in size, tilt, proximity to sun and moon (and the moon is the same size), and I'm going for the same land-to-sea ratio as earth.

Basically, it's shaped like this:

Spoiler

It doesn't cross any of the poles, it's all roughly on one side of the planet. The red lines are the spreading sea between the split supercontinent. They are roughly a thousand miles wide, give or take.

So far, I've decided that there is no land at the poles, though there may be ice caps. I know that the seas between the continents are going to be shallow, with volcanic rifts running along the bottom in the middle. I know that a spreading supercontinent means rising temperatures, rising seas, and an increase in precipitation (leaving the icehouse effect). I read something about argonite seas, but I didn't get anything from it.

That brings me to my first question: is there more land in this world than on modern earth, due to the icehouse effect?

My second question: should the ice caps be touching the northern and southern edges of my split-supercontinent, or should there be some open water in between? What effects would either have?

On the east side of the supercontinent, you have one long diagonal line going nearly pole to pole with only one hundred-mile-or-so split in the middle...what kind of effect would that have on weather/climate?

What kind of effect would such a large ocean have on, well, everything? Huge storms? Gigantic waves? Would someone be able to sail a boat out there? Also, could there reasonably be islands out there in the middle, like hawaii? I can't see any reason why not, but it doesn't hurt to ask.

As far as I can tell, each continent is about the size of asia, give or take...should the interiors be dry and desertlike? Or do the seas in between mitigate that?

I can't think of any more questions at the moment...are there any things I didn't mention that you want to comment on?

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While I'm at it, what kind of effect would two or more moons have on a planet? For instance, the moons from Skyrim? Being so large or close?

Would it be possible for one smaller, livable planet to orbit another not-much-larger planet, much like a moon? Would they have to be farther apart?

I appreciate any help or thoughts!

[Yora]

There would be a bit more dry land at times when there is lots of ice at the poles than at times when there is no ice at all. But the difference is pretty much insignificant, probably less than 1% of the land surface area.

You could have the ice caps reach the land or not, that would depend entirely on how large they are. Either way, I don't think it makes a major difference that would have to be accounted for.

In America you have a line that runs from almost the north pole to almost the south pole. Of course this does have an effect on weather patterns, but since that same effect would also be found on Earth, there is probably nothing special about it.

Having a single continent does have effect on ocean currents that increase the likelyhood of certain chemical catastrophes, but there have been situations like that on Earth at least twice, and most of the time the climate and environment did just fine with it. Conditions on the ocean would probably be similar to the Pacific, not sure if it makes a difference if you increase it 50% in size.
Islands are not a problem, as most pacific islands seem to originate from underwater volcanos that rise above sea level. You can have as many or as few as you want to.

The interior of the continents would be "relatively dry", but more than distance from the sea, desserts are affected by mountains that block the movement of clouds. And the sea in the middle should indeed help to add extra moisture to the air.
But climate is incredibly complicated and not particularly well understood, so even in the best case scenario you would have to make a lot of guessing when it comes to creating vegetation patterns for that world.
Out of a hunch, I would say put lush jungles on the shores of the central sea near the equator followed by steppes farther inland. Rain would collect near large mountains and so on one side you would have more moisture and on the other side less moisture than average, depending on the direction of the wind.

The effects of moons depends entirely on the number, sizes, and distances of the moons. The possible configurations are endless and there's a big number that would have about the same effect as seen on Earth. You can put into the sky whatever you want, as long as you don't give any specific numbers for mass or distance.
Even if you have a double planet, there's no reason not to have one inhabited and the other barren. Generally, I think the more moons and other planets you have, the higher the chances for life, as it reduces the chance of meteor strikes with the gravity of the other bodies catching a lot of them that come dangerously close.
With more than one moon of siginificant size, tides would be more variable. At some times the pull of the moons would cancel each other out and you have almost no change in tides, at other times the pull would add up creating much stronger tidal changes. If it's just two moons, it still wouldn't be too difficult to figure out the pattern and know what to expect at what times, allowing costal villages and sailors to prepare accordingly.

[wonderfulspam]

It seems as though you are accounting for tectonic plate shift and trying to make this world as real as possible (a noble goal), given that, I think that the nature of the continent and the way that it is spreading would cause a major group of islands on some part of the globe. The main reason would be because the tectonic plates are moving away from each other and crashing into other plates behind them. Just an idea.

Also, this would be a Pangaea like continent so you might want to look at information about that in creating your land masses.

[arkham618]

No land at the poles means ocean water freely circulates from the equator, moderating global temperatures. You're not likely to see much ice pack, and then only in the dead of winter. There will also be boreal forest farther north than on Earth, in areas that would otherwise be tundra (due to the absence of permafrost).

What is the diagonal line on the east coast? A mountain range? That would form a barrier against the moonsoon, resulting in a steamy coastal region fronting vast expanses of steppe and desert beyond the mountains.

The superocean would generate extremely powerful cyclonic storms. Like super-typhoons. There would be small volcanic islands all over the place. You're also likely to see large island arcs (like the Japanese Archipelago or the Aleutian Islands) just offshore from the supercontinent, where the oceanic plate is subducting beneath the separating continental plates.

The continental interiors would be dry, but not hyperarid because of the inland seas. The seas themselves, however, would be more saline than the superocean, and could -- absent an outlet -- even periodically dessicate, leaving behind exposed abyssal plains covered in salt pan and a few large brine lakes. This happened to the Mediterranean at least once (~5 million years ago), due to the closure of the Strait of Gibraltar.

Multiple large moons would greatly complicate the tides and might cause a slightly higher incidence of earthquakes.

Two planets of comparable size could orbit their common center of mass. They would almost certainly be tidally locked to one another, but there would still be a day-night cycle as they revolve about the barycenter.

The Roche radius sets the limit for how close a satellite can approach its primary before disintegrating.

[Seharvepernfan]

Updated World Map:

Spoiler

Okay, that entire picture is the world map. It is not completely detailed yet, and is not final. It repeats east/west at the far right end, where I've redrawn (poorly) the westernmost tips of continents 1 and 2. The black circles are the poles. The horizontal line is the equator, obviously. The arrows are the directions the plates under them are going. There are some erased lines that still show, but it's easy to tell.

I did not take into account the fact that the land near the poles is going to be scrunched up, and the land at the equator bloated, let's imagine that the map shows an equalized view of the land (where one inch is always X miles, everywhere on the map).

For now, let's ignore all the land east of the purple line. I haven't decided if I want it there or not yet. I think that, as drawn, my three continents aren't large enough to be all the land mass of the planet, so I toyed with adding another section.

The red lines are the rifts where the continents are breaking apart. Continent #1 contains two continental plates, the southern one is colliding with (and going underneath) the northern one at the mountain range just south of the equator. The southern one is splitting with itself at the small red line (a valley that is flooding with seawater). That mountain range where the continents are colliding is this world's Himalayas - the Sky Pillars. The orange section is where I want the world's largest desert to be (the Sea of Fire), more on that later.

The three mountain ranges with the green dots next to them aren't final, I'm not sure if I want them there. They are old ranges, from previous collisions. They need to be somewhere, however.

I haven't added in any lakes, self-contained seas, or rivers, but they will all be in there eventually. I want to make use of lakes, small and large. I'm thinking more than earth has today.

The four closest islands to continent #1 are actually part of the continent, but are isolated due to flooding, similar to the UK. The shelf continues far to the west, to the north-south running island chain. You can somewhat see the line. I think I made the line/islands too far out. I also need to add in more islands, with a few tiny ocean plates like southeast asia has. On a similar note, the area where #1 is closest to #3 is probably going to have its own little plate, making it volcanic and giving it several little islands (like the carribean? is it volcanic?).

The west coast and islands of continent #1 are going to be tropical jungles, as is the northeastern tip. If the mountain range with the green dot is actually there, then everything west of it is jungle or fertile grassland.

I want the south edge of the Sky Pillars to be like the south edge of the Himalayas; abrupt. To the north of that line is rolling mountains for hundreds of miles. The north side is supposed to be arid and hot. I wanted the east end of the south side to be temperate and rainy, with the west end being dry and warm, but I think it would be the opposite as drawn. I also think I drew the line a bit too far north for the south end to be temperate at all - I need to do something about that, but I'm not sure what. Perhaps if the mountain range with the green dot extended further south? I don't know if two perpendicular mountain ranges can exist like that.

The land around the sea with the thin red line is going to be mostly temperate, and probably the most fertile in the world. Let's call it "The Cradle". That's going to be the "europe" of this world, with many kingdoms all near each other. I figure with two lines of mountains that both catch the easterly rains from the ocean to the west (along with an inner sea - the Crimson Sea), it will be plenty rainy with many rivers.

I just read that when rifting happens, it creates mountains on both sides of the rift...that seemed counter-intuitive to me, so I apparently need to make a lot more mountains along the red-line sea coasts. I figured the inner sea-coasts would be low and flat, probably swampy near the water, but if they're supposed to be mountainous...

The western archipelagos of continents 1 & 2 are pretty close to the poles, but I expect them to be a lot like british columbia - cool and wet.

Continent #2, I haven't put as much thought into. I imagine that the very north edge is going to be tundra, maybe with some ice covering the edge and extending into the ocean a bit. I imagine that, in general, it will be forested west and north, and steppes south and east. Beyond that, I don't have anything.

Continent #3, I'm even less sure about. I know that I want its east edge to be mountainous, just like continent #1. However, I picture its mountains to be like the ones on the west side of north america - not currently colliding with the ocean plate, but sliding along it. They won't be as tall or forbidding as the ones on the south end of #1. I think #3 will be mostly dry, with scrub deserts and tan-colored plains, any forests will probably be boreal and northern, except for jungle along the east coast and south tip.

On continents 2 & 3, most of the population will be along the coasts of the red-line seas. Continent #1 will likewise have people living on its coasts all along the west, north, and eastern edges, but not nearly as many as around the Crimson Sea.

I want the Cradle to be temperate, with deciduous trees, and snow in the winter. Near the southern mountains of continent #1, I want boreal forests and snow, with a "cold" climate. However, I know that since pretty much all of the southern hemisphere of this world is ocean, it will likely not be cold at all. Should I place another continent somewhere in the south hemisphere to make it believable?

No land at the poles means ocean water freely circulates from the equator, moderating global temperatures.

Does this counter-balance the icehouse effect of a (recently broken) supercontinent? Those inner seas are at least a thousand miles wide, so they've had plenty of time to affect the climate.

You're not likely to see much ice pack, and then only in the dead of winter. There will also be boreal forest farther north than on Earth, in areas that would otherwise be tundra (due to the absence of permafrost).

Will there be any tundra at all?

What is the diagonal line on the east coast? A mountain range?
That would form a barrier against the moonsoon, resulting in a steamy coastal region fronting vast expanses of steppe and desert beyond the mountains.

Yes, pretty much. I mostly guessed this. I know the inner seas will mitigate the dryness, but probably not enough to keep #3 from being mostly dry.

Also, on earth, the rockies/andies line is mostly north/south, whereas this line is very diagonal...which is why I asked if that would have any strange effects.

The superocean would generate extremely powerful cyclonic storms. Like super-typhoons.

This is what I expected. Where would these things hit? Above, I decided that on the southern hemisphere part of #1, the wind was going to blow east from west. I bet those western islands get smacked hard, but what about the eastern mountain ranges? Do they get hit with west-roving storms? I know next to nothing about wind patterns, cells, jet streams, and so on.

There would be small volcanic islands all over the place. You're also likely to see large island arcs (like the Japanese Archipelago or the Aleutian Islands) just offshore from the supercontinent, where the oceanic plate is subducting beneath the separating continental plates.

Okay, cool. I like the idea of tons of little islands. I did have some island arcs. I figure that my world is a flipped version of ours when it comes to that: we have the rockies and andies forming a strong western boundary on earth, whereas eastern asia mostly just slopes off into the sea gradually, with tons of islands and wet coastal areas (exceptions exist, of course).

Anyway, my point is that in my world, all those island chains are going to be on the west side.

The continental interiors would be dry, but not hyperarid because of the inland seas. The seas themselves, however, would be more saline than the superocean, and could -- absent an outlet -- even periodically dessicate, leaving behind exposed abyssal plains covered in salt pan and a few large brine lakes. This happened to the Mediterranean at least once (~5 million years ago), due to the closure of the Strait of Gibraltar.

They're not so much seas as thin strips of ocean. It's much more apparent with this updated map.

I do want a sea or two somewhere on this map that is mostly inland and has done that before, probably on continent #3.

It seems as though you are accounting for tectonic plate shift and trying to make this world as real as possible (a noble goal), given that, I think that the nature of the continent and the way that it is spreading would cause a major group of islands on some part of the globe. The main reason would be because the tectonic plates are moving away from each other and crashing into other plates behind them. Just an idea.

Yes, I'm trying to make it as realistic as possible, while still allowing for some creative license.

So, you mean somewhere way out in the middle of the ocean? Or like what I have to the west of continent #1?

The interior of the continents would be "relatively dry", but more than distance from the sea, desserts are affected by mountains that block the movement of clouds. And the sea in the middle should indeed help to add extra moisture to the air.

I've taken that into account in a few places, but I don't know where the clouds are going to be coming from in all areas.

Islands are not a problem, as most pacific islands seem to originate from underwater volcanos that rise above sea level. You can have as many or as few as you want to.

Perfect.

But climate is incredibly complicated and not particularly well understood, so even in the best case scenario you would have to make a lot of guessing when it comes to creating vegetation patterns for that world.

I figured, but I want to learn as much as I can before I do that.

Out of a hunch, I would say put lush jungles on the shores of the central sea near the equator followed by steppes farther inland. Rain would collect near large mountains and so on one side you would have more moisture and on the other side less moisture than average, depending on the direction of the wind.

Advice taken.

As for the moons and other planet, I was just wondering if it was possible to have another inhabited planet instead of a moon. Imagine looking up at night and seeing a small earth instead of the moon - if it had cities, you'd see them during its night. If it were night for you and day for them (on your side of them), that woul be quite a sight.

I had an idea for a world where monsters/evil races would "come down" periodically to raid/hunt on the pc's planet, via teleportation/gate magic.

Ideally, the pc's planet and the moon-planet would orbit each other while orbiting the sun, and each would spin. That doesn't seem possible, so I may have to handwave it, if I go for that.

[Yora]

This looks quite good. I see only that one arrow north of the thin red line that is impossible. That one can't be there. However, the thin red line itself seems to be basically the same thing as the East African Rift. Just remove that one arrow that goes in the wrong direction and everything else is still working.
With the great mountain range south of it, don't think of Himalayas but of the Andes. With the Himalayas, you have two plates of land crust colliding and crumpling up. The Andes are created by oceanic crust being pushed under land crust. If you want details, look up the Peru-Chile Trench. That's exactly the situation you have with those mountains. The Andes are already massive, but since it's your fantasy world, you can easily decide to have them 50% higher if you want to. As far as I know, the Andes are also very steep on the ocean side, but rise more gently over the inland side, matching your description.

How much land and water your world has is also free to be chosen by you. As far as it is understood, any ratio of land to water from 0% to 100% is possible and it is just pure coincidence that it's about 70% on Earth. Head the Earth grown larger or smaller as asteroids clumped together, or the water content of those asteroids had been different, we would have different amounts of water on the surface. (Again, having lots of ice or no ice does not make much of a difference.)

Originally Posted by Seharvepernfan

Does this counter-balance the icehouse effect of a (recently broken) supercontinent? Those inner seas are at least a thousand miles wide, so they've had plenty of time to affect the climate.

Will there be any tundra at all?

Again, it's entirely up to you. With these things, we're talking about a single factor out of millions that come together to determine the climate and weather of a planet. Everything said here applies really only if you have a planet that is basically identical to Earth and you change just this single one factor. But with your world, almost everything is different than Earth and there are millions of factors that won't ever be adressed here.
Even the most powerful super-computers on which dozens of world-leading experts have been working for decades are not able to correctly model the climate of Earth and they have the luxury of being able to check their simulations with reality to see how close or far off their models are. There are some generalizations to make, like it being likely to find deserts in the wind shadows of large mountains. But you won't find them only in those places, and sometimes there are places like that where there still isn't a desert.
With a fictional world, you are free to make things up. You are only definning a hundred or two hundred of the factors that would contribute to the planets climate, with millions more being left undefined. You can just assume that all those other factors match what is needed to have the climate and vegetation you want. Glaciers at sea level near the equator would require explaination, but you clearly have enough knowledge about geography and climate that simply going by intuition will get you very good results. You can still have ice caps and permafrost as much as you want, as those things depend also on the intensity of the sun and amount of clouds, and the chemical composition of the atmosphere, all factors that you won't be defining.

[arkham618]

Some helpful resources:

Creating an Earthlike Planet
Geoff's Climate Cookbook
PALEOMAP Project
Library of Paleogeography