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58

Real world: Fish lay eggs. The eggs sometimes adhere to the feathers of water birds. The birds fly from one body of water to another, and some of the eggs survive the trip. This occurs with farm ponds -- despite never being stocked, they wind up with populations of (in the American south, anyway) bream and bass, as well as inevitably snapping turtles ...


20

The reason why some rivers form a delta (Nile, Ganges, Mississippi, etc.) and some other form an estuary (Thames, Seine, etc.) is in the balance between sedimentary deposit from the river flow and sediment removal from the sea waters. When this balance is positive (the river deposits faster than the sea can remove) a delta is formed, while when the sea ...


18

Risk of cave-ins As you stated in your question, the cave which contains the technology has already caved in at least once in the past. The local populace may be fearful of the cave being unstable and, if they were to disturb it by delving inside, the cave could collapse and kill the explorers. This would discourage them from attempting to explore, the ...


17

User Liam Morris already gave a very comprehensive answer, yet there is one possibility that I would like to add. There is no reason to investigate the spring The hot spring just looks like a regular geothermal spring unless one is willing to put extraordinary effort into exploring it. Make the island have a volcanic past, like Island, Hawaii or the ...


14

So there's only a few ways this could happen 'realistically'. 1) Water comes from underground. This would require a lot of really unlikely scenarios though and probably wouldn't be stable for long. Imagine a tube running from under the oceans all the way to the middle of the mountain ranges. Then having the temperature and pressure force the water to the ...


12

I'm guessing that your question about endorheic basins is about the buildup of salt and other minerals. Certainly there are many aquatic animals who live in fresh water and many that live in salt water, but not many who are okay with a change from the former to the latter over time. The solution to that (no pun intended) is a lake that doesn't get the ...


11

How might these bowl mountains form? Massive volcanic eruptions, like Santorini, Krakatoa and Mount Saint Helens. They tend to leave a nice bowl behind, which, if not filled by sea water, can fit your purpose. Even Yellowstone is a giant super volcanic caldera.


10

You ask about a portion of the core being displaced toward the surface. This would move the center of mass toward the surface of the earth. How much of the core moves, what the shape is of the part that moves, and how far that bit of core moves all matter when determining the effect. If, for instance, some of the core reaches the surface we have a new ...


9

The spring emerges from a local cave which has been filled / caved in by a past civilisation, since the water is secretly heated by engineered means. Any society that can create engineering that lasts thousands of years, is probably capable of covering up the the cave so it looks like (and in fact is) solid rock. As far as the locals are concerned, ...


9

Would vulcanism work for you? Vulcanic eruptions can create flowes without rain. The obvious candidate would be Magma flows. This is the moon Io, magmaflows of basalt lava crawl over the surface for hundreds of kilometers [6]. If you want liquids other than molten rock, check out cryo-vulcanism [1]. Water, ammonia, methane or some mixed slurries don't ...


9

The major problem is that the mantle is not made of liquid magma as Holywood likes to portray. It is rock solid, no pun intended. The fact that it moves on a geological time scale helps keeping the lay idea of a liquid mantle alive. So, the core went to the surface. That presents three problems: Moving it there. It won't be like a bubble working its way ...


8

Volcanoes might well produce a number of such bowls. There are several of them around Earth. It does not even require a massive explosive event. As L.Dutch mentioned, Yellowstone is such a place. There is also such a valley in New Mexico called Valles Caldera. It's really quite picturesque. https://en.wikipedia.org/wiki/Valles_Caldera Smaller round ...


6

Let's assume a landmass disappears from the face of Earth, leaving a hole with the depth of average ocean's depth - 3.7 km. Let's also ignore any continental shelf that our disappearing land has and assume that it just leaves a clean hole 3.7 km deep. The surface area of Earth's oceans is 361,900,000 sq. km. Let's ignore the shallows and assume that the ...


6

Tectonic plates come in various sizes. Among them there are also the so called microplates, These plates are often grouped with an adjacent major plate on a major plate map. For purposes of this list, a microplate is any plate with an area less than 1 million km2. Some models identify more minor plates within current orogens (events that lead to a large ...


5

Underground Water Credit to Liam Morris If there is no surface water on your world, perhaps there are underground rivers and lakes. Plants could evolve to grow their roots into these waters and their leaves would grow on the surface. Imagine caves like these where roots hang from the ceiling as though they were stalactites all around the world. Animals ...


5

Can't happen with an Earth-like planet How do you move millions of tons of water from lower elevation to higher elevation? On Earth, the only mechanism to do so is evaporation of water into the atmosphere. If you want no rain or snow, then that is ruled out. What other mechanisms could possibly move such a large mass of water without evaporating it? There ...


4

Tides (lots of handwavium here) Imagine that your planet is really very flat, but it has some very wide craters, whose rim is high just a dozen meters above sea level. It also has a massive moon on a very elliptical orbit. Every N months (Earth months, for that planet it is once a month), when the moon is at the nearest, the tide makes the sea flood into ...


4

Looks fairly good. Took me a second to realise why your ocean currents were running along the map edges and not crossing to the other side. Areas marked 1 and 2 Depending how your oceans connect in the West and East, there are some issues. If they act like typical spherical planet oceans through the magical firmanent, then they need to cross the map ...


4

The maps look good! Two main things I would change though. The size of the swamps, and the different biomes on either side of most mountains. Usually, (for tall peaked mountains) the moisture levels on one side would be vastly different from the moisture levels on the other side. Which you did sometimes, but not always.


4

Nice work. Only comment I have is regarding your tectonic map. Plates On a world with similar tectonic activity that we see on Earth, the edges of tectonic plates often break apart or merge leading to smaller plates in addition to the larger ones. I would recommend adding some of these smaller plates at the collision points of continental plates ...


4

If you mean geographical requirements, then all you need is, A body of water (preferably salty) Some land (the soily or sandy type) that is lower or just above sea level (optional) A river (the fresh kind) If you put these together, and the river is depositing sediment from its bed faster than the ocean/sea can take it away, then boom, you got yourself ...


4

Take a valley, put-on a geothermal vent and cover it with thousands feet of ice. You get something like lake Vostok. Under high pressure from the ice above, water stays liquid at -3°C. It may have been connected to the sea and is now sealed-off from the rest of the world for millions of years. Despite that, the bottom ice-layer sample reveals richness in ...


4

10 thousands year is an awful lot of time for a river. Just look at how the Netherlands changed in the last 600 years: Or look at how the Po river delta changed over the past 300 years: The Adriatic sea is called like this because of Adria, a city which was once a big port and now is several kilometers inland. And the examples above only deal with the ...


3

Nice work 👍 The last illustration of Coriolis effect need to be tweaked because it only works on round world. Unless you flip one of them and make the arrows combine in the equator to form a giant constant cyclone 😁 Good luck


3

Our oceans come from volcanic activity lifting gases out out of the world's core. A world like you describe naturally forming to be volcanic enough to support chemotrophs without oceans is not very likely. The closest you could come is a runaway greenhouse world like Venus with VERY tall mountains. At 55km, Venus's atmosphere is Earth like except for ...


3

The first thing which comes to my mind is having a water cycle similar to the one we have on earth, except that instead of raining the water condenses only once near the top of the mountains, and drips directly back to the rivers/glaciers. It's not very different from what we have, and probably happens sometimes on earth, when correct temperature/pressure ...


3

The easy answer is "yup! mountains!" the truth is more complex Sometimes we get caught up too much in "reality." In "reality," this planet cannot exist as you've described. But what's the fun in that? Therefore, I'm going to utterly ignore all aspects of physics that would either (a) tear this planet apart or (b) force it to eventually become spherical. ...


3

Zeiss Ikon has a good answer but you also need to bear in mind that some lakes cannot ever become havens for complex aquatic life. For example if the country rock is limestone the water pH may consequently be too high to support the plant life that forms the base of the pond food-chain. Similarly a number of igneous rocks create acidic conditions that have ...


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