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How the continents look like is mostly determined by what is going on underneath the surface. Earth looks the way it does because of plate tectonics. We have several major continents with major landforms clearly linked to tectonic plates like mid-ocean ridges or mountain ranges often existing in one long line along plate boundaries. Other planets do not have plate tectonics. The topography on Mars or Venus was built primarily by shield volcanoes and erosion. I do not know why Earth has plate tectonics while Mars and Venus don't and I don't think anyone knows. It could be that the impact that created the Moon had an effect. It could be that tidal heating from the Moon's gravity helped (especially early on when the Moon was much closer). It could be that other factors were much more important and the Moon has barely any impact.

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Regarding your fictional world, how exactly did that cataclysm happen?

There are theories that Venus underwent a global resurfacing event some 300-500 million years ago, which covered the entire surface in lava and essentially erased the previous topography. Since then, Venus' surface was mostly shaped by volcanoes and wind erosion forming more or less randomly distributed highlands, which would be continents if Venus had water. If that sounds fitting for your world, you can look up Venus' topography for inspiration.

Mars has an interesting topography with the southern hemisphere being several kilometers higher than the northern hemisphere. With enough water, that would mean one supercontinent covering half the planet and one big ocean covering the other half. Why it looks that way is still an open question afaik, I have seen a theory that a big impact may have caused it. Anyway, if your god grabbed the material for the new moon exclusively from one side of the planet (quite likely, I assume the whole population that angered him lived on that Pangea-like continent), that side could become the new mega-ocean. In that case, the land and ocean in your world may have simply switched places and without plate tectonics or other major resurfacing events, they will mostly stay where they are.

If you want your world to have plate tectonics, you could look at models of Earth in the past and future to get an idea of which landforms are possible and how they could have developed over time.

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The kind of cataclysm you're talking about depends greatly on how much material you're ejecting into space, and also quite a bit on how far away it ends up. You say that it is a city that's getting yeeted out the planetary airlock, though you call it Mars-like based on its climate. That's a huge range. You're going to have to decide where in that size range it falls in order to get any workable details.

If the amount of crust getting cosmically defenestrated is the size of a city, there will be little to no impact on the planet at large. It doesn't matter how far away it ends up in this scenario. It's a small asteroid, too small to fall into a spherical shape, and it's going to need all kinds of magic to have anything to make it habitable, like air or sufficient gravity.

If on the other hand it's the size of Mars, the entire biosphere of the original planet will be utterly destroyed, the surface liquified, and no kind of life will be able to exist there for several million years (which is what actually happened to earth).

You'll need to provide more details.

No, plate tectonics is based on heat from the earths mantle.

Think of tectonic plates as part of a cracked shell that all fit snugly together over the earth's molten mantle.

Heat from radioactive processes within then causes the plates to move.

For your story, it would be a piece of your planets cracked shell being removed and the molten stuff underneath exposed. I can only imagine the massive devastation as the rest of the plates try to move to fill in the gap.

There is a forum for this /r/worldbuilding. Many of these questions are asked there in the context you are looking for.

The short answers are:

We don't usually consider a satellite to have any influence on geography, geology or climate other than tides. A satellite and the tides are usually considered necessary for the evolution of life.

>Also, what would happen if a natural satellite suddenly appears around a planet that did not had one ?

Largely depends on the mass and distance.

>creating a new Mars-like (like red desert planet) satellite directly from the crust of the original Earth-like planet they lived on

Ripping that much mass from the planet is much more devastating than the moon itself.

>it destroys Pangea and reshapes the lands.

It reshapes the planet. Gravity isn't going to tolerate a missing chunk and gravity is going to force the planet back into round or nearly so. Massive devastation as in earthquakes beyond imagination until its settled.

Yeah I thought of this mega-ocean in the middle of everything. I just thought that this new moon could impact geography because of its presence.

It's been a long while since I studied this stuff, but I believe the heat generated through the natural decay of uranium, with the insulation of earth's rocks, causes differential heating to the interior of the earth, creating convection cycles within the mantle. This drives plate tectonics

Maybe not in the same scale as plate tectonics, but the shaping of continents is effected by tides causing coastal erosion and accreciation.

When I say Mars-like, I'm thinking of its landscapes. It's not meant to be habitable, it's supposed to be a warning to other species that want to rebel.

Well, if it's city sized, then you have your answer. It's too small to have any impact on the planet. It's going to be a floating clump of dirt.

No where near the same scale as plate tectonics. On the local level tides will cause erosion but when we do modeling of tectonics with something like gplates you aren't modeling the small time scale erosionable bits (like the coastline) anyway you are modeling masses of rock. The fine details that would be effected by tidal erosion are just left to artistic interpretation once you make more detailed maps.

Kinda true (slab-pull also has an effect but it sort of needs plate tectonics to already exist to drive plate tectonics) but that's happening in all planets, so what is special about Earth that it developed plate tectonics while Venus or Mars didn't?

It certainly has an impact on geography on a smaller scale if it is big enough. A moon the size of Mars would create huge tides that would impact the shores all over the planet. Large mudflats that stretch for many kilometers, connect islands to the mainland for a few hours twice per day while flooded during high tides could be very common features on your planet. Coastal cities would have to deal with tides several meters high and build accordingly etc. Of course, the smaller the moon and the further away from the planet it is, the less it impacts your planet.

Love your word choices.

> Planetary airlock

>Cosmically defenestrated

Cosmic Defenestration sounds like interdimensional astral projecting.

If one planet does a near miss flyby of another planet it can form one one three general types of formations; strips, bulges or holes.

The Earth has several visible strips, Mars has a clearly visible bulge and hole.

Hope that helps

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Assuming that the planet is bigger than the moon, then the planet would have a much larger impact on the moon than the moon would have on the planet.

Look at the moons of Jupiter and Saturn. They are squeezed and compressed by the planet's gravity, which causes volcanism. Io is the extreme example, as it is closest to Jupiter. But Ganymede has a liquid ocean under it's ice largely because the gravity of the nearby planet is squeezing it and the friction is warming up the interior.

Also tidal locking is a thing. That's good for your story. A moon that is tidally locked to it's planet (like ours is) will always face the planet. From our perspective the moon doesn't rotate, it's always showing us the same face. That's why the moon has a dark side. Not because it's literally dark, but because before we invented spacecraft no one had ever seen it, it was unknown.

So your theoretical moon would have the city always facing the planet, to remind the planet's inhabitants of what happened (although it would likely be much to far away to make out the city). It could also be a sulphurous volcanic wasteland, much like the surface of Io due to tidal effects.

As for the moon's effect on the planet, that depends on the size of the moon and how close it is to the planet. Too close and too large and tidal effect will break the moon apart. You seem to have settled on a small, close moon which likely would have very little effect on the larger planet. As an example the 2 small moons of Mars have almost no effect on the planet at all.

Our moon causes ocean tides on Earth. It may also have an effect on plate tectonics, not so much with moving them, but may be at least part of what's keeping them apart and not allowing them to bind together (The jury is still out on that one, the oceans being subducted and releasing water seems to play a much larger role). On the other hand, the Earth caused the moon to become tidally locked and also causes a regular pattern of moonquakes.

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I don't think I've read anything on it but in theory it doesn't seem out of place to imagine there are tidal effects of the moon on the mantle which could cause 2nd order effects on plate movement.

Without the moon, the Earth’s tides would be greatly reduced. Shorelines would function more like lakes than oceans. This doesn’t change 99% of the continent, but would have a huge effect on the edges.

The moon is also responsible for stabilizing Earth’s tilt. Without it, Earth’s seasons would be different. Instead of four seasons to a year, we would have many more. This would make the habitable zone of the planet smaller, though being near the equator would still be safe.

The moon was wildly influential on the formation of the earth as it is and life. And maybe had more significant impacts such as on the formation of plate tectonics but that isn't really known or not.

So as you may know the moon was formed through an impact event between proto earth and a roughly Mars sized planet called Thea. The result of this impact was, potentially only over a few hours to days, the formation of a relatively massive moon made mostly of lighter silica rocks and material. The majority of the metals and heavier elements in the core of Thea sunk to the core of the earth giving earth an oversized core compared to its size which no doubt has contributed to earth's excellent magnetic field. This has undoubtedly contributed to the formation and protection of life on earth.

So where did Thea come from? Was it launched from elsewhere in the solar system? Well it most likely formed in the same section of the protoplanetary disc as earth did resulting in it having a very similar orbit which eventually resulted in the two colliding as they migrated and shifted within that orbit.

Now let's talk about plate tectonics. Plate techtonics is a result of internal stresses forcing the outer shell of the planet to buckle and warp until some part of it sinks into the mantle and starts the conveyer that is plate subduction and plate spreading. It is responsible for the formation and break up super continents, building of mountain ranges and island chains, for mass extinctions and vulcanism, and for both massive additions of greenhouse gasses into and sequestration of green house gasses out of the atmosphere through vulcanism and plate subduction and weathering respectively. A useful way to look at plate tectonics is to look at other similar planets and see why they didn't form plate tectonics.

Venus is a great candidate. It is similar in size to earth with the only major differences being no moon and closer to the sun. It is theorized that venus failed to form plate techtonics due to that proximity to the sun. The sun heated the crust of venus enough that, when internal forces cracked and deformed the crust of venus, those cracks were repaired through melting and the deformation was more elastic resulting in smaller cracks.

If the crust had been colder the crust would've been more brittle resulting in less elastic deformation, larger cracks, and cracks that didn't heal as quickly through heat and melting. Because venus' crust never overcame this it never truly started the process of subduction and so no plate techtonics.

Interestingly enough the result of this was, we think at least, the build up of pressure and heat below the crust since there was no way to consistently vent and release this energy. Eventually this reaches a point where the pressure bursts forth causing some sort of chain reaction and resulting in what is known as a planetary resurfacing, ie the entire surface of the planet was simultaneously covered in massive lava flows pretty much all at once. The result in a massive release of volcanic gasses forming venus' current atmosphere and ensuring that venus would always be a hellscape planet with intense pressure and heat. It's thought this has occurred two or more times in venus' history. Earth and Mars have also had massive bouts of vulcanism, the largest of which on earth coincides with the largest mass extinction event in earth's history (the Siberia traps). It's possible that the trigger for such massive widespread vulcanism may have been a large impact event like what's theorized may have set off mars' mass vulcanism events.

Speaking of Mars, Mars never formed plate tectonics either. The idea for this is that it simply cooled too quickly. The heat and energy that causes buckling and deformation of the crust is caused by the heat released by the left over heat and radioactivity of the core. With such a small core Mars simply cooled too much before plate techtonics could get going. This is also why Mars has no magnetic field, the core and mantle has cooled to the point that the fluid dynamo caused by the different rotations of the core and the mantle material weakened significantly. All of this likely because Mars is just too small of a planet.

Now let's go back to earth and talk a but about the moon and plate techtonics. The moon may have contributed to plate tectonics in a couple ways. First and foremost it increased the size of the planet and the core significantly. The addition of so much heat and radioactive material no doubt helped provide more energy for internal forces to deform and crack the crust.

The moon may have also contributed to those forced through tidal forces. The moon is not only massive in relation to earth compared to most moons and their orbital bodies but it also used to be significantly closer to earth and orbiting much faster. Just after it's formation the moon would've orbited 15-20,000 miles away compared to its current 238,000 miles, would have been 15× bigger in the sky, and had an orbit just under 24 hours. While the moon would quickly move farther away from earth, the energy lost in that process was lost through tidal friction which would have contributed to the deformation and buckling of the crust (once it had resolidified).

The impact may have also helped earth avoid venus' fate. The early sun was significantly more luminous (and about 2-4 times larger) after it was initially formed and steadily decreased in luminosity until it was about 100 million years old. After which it has gained about 10% luminosity every billion years since. The moon formed 60 to 175 million years after the formation of the solar system. That may have helped the early earth avoid that period of intense solar energy that likely contributed to preventing venus from forming plate techtonics. The impact that formed the moon also imparted a huge amount of rotational energy to the earth moon system with a "day" just after formation being somewhere between 1.5 and 6 hours long. That quick rotation not only imparted a lot of tidal friction on earth but also prevented any one bit of crust from being baked by the sun for too long.

Venus in comparison has a rotational period of 243 earth days and will eventually become tidally locked with the sun like mercury is. Granted venus rotated much faster just after the formation of the solar system and had its rotational energy sapped away by tidal friction from the sun much faster than earth but the point still stands.

So all in all the impact that formed the moon is likely a significant contributer to earth's ability to start up the process of plate techtonics and undoubtedly contributed to the formation of life through its contribution to earth's magnetic field but also through the influence of tides as a driver of evolution and the contribution to earth's short day.

Now how does this help you with your divine punishment moon? Who knows. The moon maybe helped start plate tectonics but if you've got a super continent without one then it already exists for you. The majority of the ways the moon influences the evolution of the earth was in its cataclysmic formation event. If the formation is simply a snap of some gods fingers then most of this doesn't matter. If the people of your planet survive this formation then the formation will not be close to the formation of the earth, since the impact that formed the moon turned the earth into a molten ball for at least a couple million years before the crust reformed (and may have even turned the earth into a gaseous donut of vaporizers rock and metal for a little bit depending on how the impact happened exactly). If any life had existed it wouldn't have survived although that point is irreverent since life didn't form for several hundreds of millions of years after the formation of the moon and that was the most basic of basic life. Complex life took another couple billion years or so. So good luck with your world building. Hope my post helps at least with some ideas.

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Hold up a sec because Europa is contorted by the gravity of Jupiter and causes it to shoot giant plumes of water into space

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In all seriousness, couldn't Age of Ultron be used as an example? I can't remember if that's a full city or just a section.

There are also moons that have such a strong reaction to their planet that they have geological activity. Enceladus and Europa both have liquid oceans because of the heat generated by tidal flexing.

If your moon was large enough it could cause enough upheaval that over a long period of time it could change the landscape either through much more active tectonics or from things like volcanos which could look very different.

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Depends on how this satellite was created.
Like with Moon - it's more about that part of Earth crust was thrown into orbit, giving remaining plates free space to move. Normally planetary crust is more rigid and have way less activity since all plates are tightly coupled and there's there's nowhere to move. By removing one of places rest was given ability to shuffle around, moving back and forth.

Like Mars have two satellites, but since his crust is "unbroken" - nothing happening there.

Dont forget…. While the campaigns and stories you tell now tell their own stories…. Introduce obscure lore that hints at the final story arch that wont be realized until a multitude of campaigns have played out.

As future campaigns move forward drop more hints and clues, not to give the story at this point, but to have a trail people can follow back later, amd be surprised that it wasnt noticed already when the final arch is revealed.

That the giant space-born celestial being that was cacooned within the planet was disturbed when a large chunk of it was blasted into space, startimg a series of escalating events that culminate in the race to stop the emergence that would destroy everything in the starsystem this world exists within.

That's exactly what I intend to do hehe

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This is incredibly fascinating and well written. Thank you

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None, the continents were already well formed before the Moon was placed in orbit. Right around the time the current continents arrived at their present location (Due to the expanding earth effect) the moon entered our solar system and was strategically aligned into its current orbit. Luckily due to the cooling of the mantle the earth has stopped expanding in diameter, so no significant changes to the current continental structure should occur...at least not at the rate it was expanding over the last 500,000 years.

Amazing stuff.

There is pretty strong evidence that about 4.5 billion years ago the moon was formed as a result of early earths collision with another celestial body about the size of Mars namely Theia. The moon is most likely not a captured object but as a result of the debris thrown up due to this impact. The moons rocks contain many of the same elements and isotopic properties as earth rocks. If it were captured this would not be the case.

Well when crashing into the planet yeah. Its gonna make a massive impact but orbiting the planet, no nothing will happen.

I realize I didn't clarify well. I meant just a visual example of a city being ripped from a planet. Earth was largely unaffected.