66

Rock and clay don't burn well, leaving you with a lot of dressed stone lying around to say there was once a city here. Fire from above implies volcanoes, as we learned from Pompeii, that's actually a great way to preserve a city so that 4000 years later we know exactly what happened, down to what specific individuals were doing when it hit, so that's out. ...


52

How about a catastrophic flood? Have the city built on a large river. A landslide further up blocks the river and causes an enormous lake to form (also cutting off water supply to the city causing hardship for the inhabitants). When the dam fails...it really fails and a wall of water rushes down the valley wiping out the city and thoroughly destroying it, ...


43

I have much academic experience with some of this, especially the second part of your question. I'll address a few different sides of things. The most drastic way I can think of that could ostensibly be caused by some natural occurrence would be a low altitude meteoric air burst similar to the Tunguska event. Such an event would cause a lot of surface ...


38

Tides will still exist from the sun's pull, though they would be smaller. Solar tides are 44% of the current total and lunar tides 56%. Tides would occur at roughly noon and midnight every day. Probably some impact on life, weaker tides would stir up less nutrients, etc. Due to how tides are a drag on the earth's rotation, the earth's spin is gradually ...


35

Moved from comment to answer because I've done more research. Try the biblical account of Sodom and Gomorrah, believed to be near the coast of the Dead Sea . The cities were destroyed by means of volcanism (fire and brimstone), and 4000 years later we still don't know where they are for sure. As an argument for the effectiveness of this approach, there is ...


35

Every fourteen thirteen years, vast swarms of a locust-like creature emerge from underground, where they have been living in the larval stage for all this time. The swarm darkens the sky, and eats every last bit of organic matter that is above ground and unable to flee. This includes the leaves, branches and trunk of every tree. Fortunately, the trees can ...


30

The big unknown is the location of Prince Arthur, Edward VII's younger brother. Assuming that he wasn't in London, you get interesting story possibility #1: King Arthur II (assuming he takes that as his regnal name) is busy trying to hold a disrupted British Empire together. Militarily, the Empire isn't much weakened: the Royal Navy is mostly in bases away ...


27

Frame challenge You say the trolls can't float. However ... Average human mass - 50 kg Average human height - 173 cm Average troll mass - 90,700 kg Average troll height - 30 m By the square cube law, the trolls weigh very little compared to their height. They will float easily. Answer If you are worried they are not waterproof then wrap them in ...


25

That's some extreme time dilation. It is possible, but the black hole needs to be insanely massive for your ship to orbit it without falling into the event horizon and have the proper amount of time pass. Gravitational time dilation goes like this: $$t_0 = t_f \sqrt{1-{{r_0}\over{r}}}$$ Where, $t_0$ is the proper time between events A and B for a slow-...


24

Scale it up - you thought "a meteor strike is too visible". Good! If your impact crater is deep enough, people are going to think "valley", not "crater". Hit them with 3-or-more meteors in a row, and dig that crater deep. It'll grind that city to dust, and bury it under rocks! Then let the basin flood, and all your evidence is hidden at the bottom of a ...


23

Never For one thing, to my knowledge, no veins of Iron have ever been found in volcanic breccia so large deposits of steel (iron) found in one would immediately be suspicious. Additionally, cars are made up of many materials that over such a short time would not decompose. More surprising would be finding the concentrations of aluminum and platinum, let ...


16

TL;DR - Without Britain, Germany wins both World Wars and becomes the new world superpower, the British Empire slowly falls apart, and large-scale advanced radar development gets set back a few years. I disagree with Scott as far as his response regarding what the world would perceive the cause to be. There's no reason why the world would suspect it to be ...


16

It doesn't necessarily have to be a natural disaster in the traditional sense. It could be that a natural/weaponised biological plague tore through the population making them go completely mad. They then tore and burnt the city down. There are several historical references of ancient cities being conquered and razed to the ground by the victors, leaving no ...


15

No, it will never happen that cars buried in the ground will revert to iron ore. The scenario you described already happened, on a smaller scale, in Pompei. Tool used by the people, even bread, fruits or wine jars have been found back. No iron, copper, lead, silver or gold veins found.


14

Going with waves like @pipperchip: boats don't notice the tsunami, and even probes deployed on buoys for the purpose have a very hard time detecting it. Why would an island be bothered? Because of the rise of the seafloor leading up to the visible part. Islands that are too steep will suffer landslides until the slope is sufficient to hold. Make yours ...


14

The issue of having no living trees older than 12 years would at best indicate that some event occurred 12 years ago resulting in complete devastation of the forest in that region (note that an explorer on foot would presumably have to return to "home" every night, thus would have a limited region that he/she could explore; even with a ground vehicle, the ...


12

Small quibble - the suggestion that 'the Monarchy' would be wiped out because of the deaths of Edward VII and his immediate family seems unlikely. Heirs to the throne are like sharks teeth; get rid of one and another takes its place. Even if all Victoria's male heirs died, her daughters and their heirs would come into the succession. Her eldest daughter (...


12

Of course we can only guess, but my guess I will provide. Summary/TL;DR: In 2014, the difference wouldn't have been very big. First let's look at the effects the black death had in this history. The black death caused the demand for labor to rise, and it caused the downfall of the serf system in most of Europe. Aristocrats didn't have as much control over ...


12

Atmospheric dust by itself shouldn't have any major impact on generation or distribution of electricity. The two are unrelated. However, a fraction of the Earth's electricity production is based on current solar input, either directly or indirectly. There is the obvious: photovoltaic electricity production, which globally amounted to a total of 41.4 TWh in ...


12

I'm ~99% certain that the effects of a second celestial body on seismic activity on an Earth-like planet has been covered before (in that case, by a second Earth-like planet); if anyone can point me to it, that would be great. The conclusion - if I remember correctly, and I think I do - was that there wouldn't be any major effects in this area. I might have ...


12

A large meteor impacting would have devastating consequences on the planet, and humanity. Tsunamis would wreck countless thousands of miles of coastline. Ships would be sunk. Infrastructure destroyed. Seismic activity would cause further death and destruction. And on top of it all, the debris thrown up into the atmosphere may well obstruct the Sun, such ...


12

The inhabitants of the city developed some building materials which seemed like a good choice back then, but chemistry eventually expletived them up. The rocks and clay of the city were rich in iron oxides, specially red iron, and aluminium. Other composites in the sand, clay and rocks kept this fiery duo from reacting in a Goldschmidt process. Until one ...


12

Snowball Earth https://252mya.com/products/snowball-earth-wallpaper The Snowball Earth hypothesis proposes that for a period during the Precambrian, the Earth froze over entirely or almost entirely. https://en.wikipedia.org/wiki/Snowball_Earth The Snowball Earth hypothesis proposes that Earth surface's became entirely or nearly entirely frozen at ...


12

Gamma ray shower from a close-by supernova. The explosion of a supernova close (few tens of light year) to the Sun would bathe the Solar System in a shower of highly energetic gamma rays, which are lethal for life. Moreover, stripping over the ozone layer, it will allow also radiation from the Sun (UV, X-ray, gamma ray) to easily reach the surface. Being ...


11

Nope. The dust in the air may generate a static charge, which in turn may increase lightning (even in the absence of storms), and blocking the sun will of course limit the effectiveness of photovoltaic cells (solar panels), if not render them outright useless. However sunlight has no bearing whatsoever on the movement of electrons through conductors, most ...


11

The moon is in fact important because it stabilizes the Earth axis. Without the moon, the Earth Axis would slowly (we are talking about geological timeframes, thousand of years) change their orientation, making life on Earth much more difficult: Laskar,Joutel,Robutel: Stabilization of the Earth's obliquity by the Moon Muslims would be quite aghast because ...


11

Divert it It takes only a tiny change in the course of the asteroid to make it miss if the change is made early enough. So with a year, start designing an interceptor from bits and pieces of space and weapons programs, build a couple of them (for redundancy), and launch them with some months to spare. A big nuke, not in the asteroid but somewhere to the ...


11

Don't Panic --Hitchhiker's Guide to the Galaxy, Douglas Adams Seriously though: Everybody is certainly dead Including everyone in the special bomb shelters. Anything with enough energy to disrupt the Earth - will essentially melt or vaporize the entire Earth - including every biological entity living on, in, or over it. To give you an idea of the ...


11

This would be really bad. The United States would experience short-medium term economic devastation and be hit by major economic aftershocks for many years thereafter. Let’s make an assumption that there is broad scientific agreement that the eruption is definitely going to happen with a six month warning period (this is unlikely in practice, but a useful ...


11

How do they decelerate? If they do it by action and reaction, then they decelerate by sending mass (rocket fuel etc) ahead of them so they slow down. Mass times acceleration. Stop half the mass by accelerating the other half to twice the velocity? (Ignoring relativity.) Or stop most of it by accelerating a little bit a whole lot faster.... The kinetic ...


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