Hot answers tagged

140

It depends on your rock. Rocks like Granite, with large crystal sizes, are the result of VERY slow cooling and crystallization. So although in theory you could remelt and recrystallize this kind of rock, you'd probably need hundreds or thousands of years to do it. Basalt, a fine grained igneous rock, would be fine. It would still need quite a long cool ...


109

Crystal structure is dictated by Gibbs free energy. Once you have the right chemicals and the right conditions, nothing prevents the formation of the desired gems. The only gems you would not generally find are those with organic origins, like amber (resulting from fossilized tree resin) jet (resulting from decaying wood under high pressure) abalone (...


89

The climate of Earth has been roughed up quite a bit last century. But it has no idea what it's got coming with this portal of yours. Earth turns into Venus. Update: As R.M. pointed out, the amount of energy is not 'maybe a long term thing', it's the Major Issue. This has been fixed now. How much water are we talking? Let's say your portal is 10km below ...


82

An half submerged crater can give you a circular set of islands. You can choose among various craters: Volcanic craters, like Santorini Mountains subsided into the oceans or eroded by changing sea level, like all the coral atolls (the picture refers to French frigate shoals) Impact craters, resembling the Tycho crater all of the above can also provide ...


69

Your bridge is an atoll like Kwajalein The Kwajalein Atoll is one of the largest in the world. Following the curve of the land, I estimate that the distance from the upper left to bottom right corners of the atoll is about 104 miles, or 167 km. The straight line distance is more like 75 miles or 120 km. The width of the atoll is in the range of 500 ...


68

Before cremation About 18.5% of the human body is carbon by composition. One gram is five carats. The average human being worldwide masses 62 kg. Note that people may be larger in some countries, e.g. in the United States is 88.3 kg. $$ 62 \text{kg} \cdot 18.5\text{%} \cdot 1000 \text{ grams per kg} \cdot 5 \text{ carats per gram} \approx 57,000 \...


65

No. On this scale, the Earth is not solid and rigid. It's more like extremely hot jello, with a thin and weak crust, a layer of hot floppy jello, the "mantle", a liquid outer core (actually molten iron) that's about 1,400 miles thick, and an inner core of iron about 750 miles in radius. Films and TV programmes that show journeys to the centre of the ...


59

Getting caught in a thunderstorm is the most likely cause. This can happen even to experts if they are incautious enough to take risks with the weather. Here's an example with a paraglider. (I'll see what I can find for a hang-glider) Ewa Wisnierska was sucked into a powerful thunderstorm while training for the world paragliding championships in ...


58

It would overflow... As of right now, the Black sea is overflowing with water, leading it to push more water out to the Mediterranean than it receives. This was not necessarily the case during the last Ice Age, when it was a lake. But precipitation patterns have changed since then, so the Black Sea could not be a lake any more. The Bosporus has an unusual ...


53

Give your planet two moons with different orbits, and once a year for about 30-60 days they align on the sides of the planet perpendicular to the twin islands. The tidal forces draw enough water away to lower the sea in that area, bringing out the island.


52

Could an earth-like planet form without accessible traces of iron Without iron, you'd need a completely different biochemistry, and would in practice condemn the newcomers to a slow death. Iron is essential for hemoglobin synthesis and humans need to acquire it from food: from vegetables (most green leaves) or already concentrated in muscle tissue (by ...


50

As long as your local geography/geology permits sand deposition: a large sand bar/spit would fulfill all your requirements. Since I'm the most familiar with the geography of the Baltic, here are three examples from the region: The Hel (sic!) Peninsula The Vistula Spit The Curonian Spit The first example is a bit shorter than required (~35 km), but ...


47

For an alternative (to vulcanism) geological process, check out what was discussed in this thread at Earthscience.SE. Link to Google Map of the affected area. Basically, a very long ago tectonic collision caused part of the Earth's crust to fold in on itself and 'roll up.' Harder base rock gets wrapped around other softer layers of rock. Imagine a jelly ...


45

It would be 6,378km deep. The same depth as the radius of the Earth. The math To calculate the gravity of an infinitely flat plane we simply need to integrate the force felt from concentric rings from a radius of zero to infinity. This is a basic practice in college physics courses and is demonstrated here. It turns out, that the force on a mass above ...


44

The big rock candy planet A planet is entirely covered in oceans. Microbial life develops on this planet. This microbial life gains energy by transforming carbon dioxide into sugar. The ocean becomes very sugary. The planet's star suddenly increases in luminosity. The planet's oceans are boiled dry and all life is extinguished. The entire planet is now ...


40

Solid is a relative thing No caves in sand No caves in water No caves in magma No (permanent) caves in ice sheet No caves in soft soil No caves in peat bogs In short: No caves in anything fundamentally unstable Only caves where you have surface rock An old, geologically stable world, where the mountains have eroded down. Land is low lying and either ...


40

A real answer is a calculus problem that requires many different iffy variables that will be difficult to determine. So I am just going to ballpark it instead. In a lot of places, I have rounded or just taken sweeping approximations. It should hopefully be within an order of magnitude of the right answer. However, I think getting a realistic answer to this ...


40

How would this difference affect Earth's overall chemistry? Not much (but see below). Here's why: Let's start with some background The core–mantle differentiation event was the melting event which caused separation of the rocky mantle and the metallic core. It separated earth into two phases (in the chemical sense): Metal, which is dense so it sank to ...


37

There is no other option. The underlying rock is limestone, and it has a network of karst caves: After several attempts to build something on top of the caves, they collapsed causing damage in life and property. The solution was to simply build inside the caves. It is actually a pretty good idea. You don't have to dig too much out because the hole is ...


36

There is no evidence of construction in the soil surrounding the house. A Georgian mansion would have been built on site by craftsmen. They would have done much of their work on the land surrounding the house. Generally some evidence of this work would remain buried in the soil - cut bits of wood, broken tiles, etc. Also there would probably be an area ...


35

While bowlturner's answer provides a list of processes to work with, I think that, since this is about worldbuilding, there should be some technique in applying all of these possibilities in a practical way. Practical means, since we're not talking about software explicitly here, possible to do with pen & paper and fit it all in your head. Keep in mind,...


35

An opportunity here to link up my all time favorite episode of How It's Made: Stone Wool Insulation. It is exactly melted and recycled rock, being done commercially. The idea was inspired by "Pele's hair" which is a real thing found in Hawaii: molten basalt whipped into thin hairlike strands. In the video they show the making of artificial lava from ...


34

For a given value of 'atmosphere' we already know of one such planet. Well, Moon. Europa The smallest moon of Jupiter, Europa is interesting because it is hypothesised that the surface is made entirely of a thick layer of ice. How does this match your scenario? It's further hypothesised that under that ice, thanks to the heating produced by the Tides of ...


34

It doesn't seem to be possible using "normal" geology. You'd need a supervolcano to attain the required energies, and "piloting" one with the required precision doesn't look doable. You need to score a direct hit; getting in orbit isn't enough, since any station would have ACS thrusters and be able to both detect a coorbiting incoming missile, and avoid it. ...


34

I'm reminded strongly of Iapetus, a moon of Saturn that has a dramatic two-tone coloring. One hemisphere is quite light, while the other is dark. It almost looks like you dunked half of the moon in chocolate: Image credit: NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute. Public domain. Iapetus is tidally locked, meaning that one side ...


33

Instead of telling you it's impossible, I'll make a list of the problems you need to solve: Pressure: Pressure at Earth's center is $3.65 \times 10^{11} \ \mbox{Pa}$. Whatever enclosure you build is subject to that. If you made a solid block of diamond (one of the least compressible materials, with a bulk modulus of $4.43 \times 10^{11} \ \mbox{Pa}$), you'...


33

It is believed that most of the metals in Earth's crust came in the late heavy bombardment, since the metals which were part of the original materials of Earth would have sunk to the core due to its higher density while the Earth was a ball of liquified magma. So you only have to say that there was no late heavy bombardment (or it wasn't that heavy) to ...


33

You could use a large mid-ocean ridge, like the Mid-Atlantic ridge, and then play around with sea levels. Mid-ocean ridges occur at (divergent) plate boundaries, and can be thousands of kilometers long. They can rise high above the sea floor, at times breaking through into islands. So, here's how you make your road: Take a rather large plate boundary and ...


33

Its not too much different from obsidian First off, lapis lazuli is a gemstone mostly formed of the mineral lazurite. Lazurite has the same blue appearance as lapis lazuli, so it might be more reasonable (and accurate) to say that your island is made of lazurite. Based on lazurite's hardness (5-5.5 on the Mohs scale) and density (~2400 kg/m$^2$); it ...


31

All the answers seem to be focusing on using geological methods. For a completely different natural methodology consider the possibility of long chains of floating colonial sea life forming your roadways on the sea. Some hybrid between coral and jellyfish possibly in symbiosis with sea weed plants or other photosynthetic algae. Floating Sargassum sea weed ...


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