# How long would it take Nature to destroy the evidence of human existence? **URL:** \ **Category:** Great Debates\ **Created:** [April 4, 2006, 10:39am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228 "2006-04-04T10:39:40Z")\ **Posts on this page:** 20\ **Page:** 5
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [April 10, 2006, 2:07am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/81 "2006-04-10T02:07:07Z")
> [@renzuken\_x\_2](#): > > i know its ment to be on earth but what about all the parts or man made materials that orbit the earth from space shuttles, its a sure sign that something left the planet and beeing that in space theres not much that can erode the metal (well, not that i know of). I didn’t see this before I posted the satellite thing. Most stuff in low earth orbit will decay in a relatively short time - if we stop launching stuff into space, almost all of it will have come back to earth within a few hundred to a few thousand years. I’m not sure how long some of the geostationary satellites will last - maybe a long time. The LAGEOS ones I mentioned are intentionally places in an ultra-stable orbit, so I would guess that they will be the longevity champs. The OP already disallowed artifacts on the moon. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 10, 2006, 2:27am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/82 "2006-04-10T02:27:13Z")
Someone earlier mentioned that geosynchronous satellites drift out of orbit… That’s partly true. After a while, they’re not in the exact orbit we want them to be in (that is to say, they’re not staying over the place we want them to stay over), but they’re still in orbit, and a very high one. At worst, a meteorite might smack right into one, but I suspect that the expected number of such events in the next 5 billion years is less than 1: Both meteors and satellites are very small targets. I don’t know of any natural phenomenon which could bring geosynch satellites down in bulk, short of the death of the Sun in several billion years. And even then, there’s at least five space probes which would survive, though it’s unlikely any aliens would ever find them. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [April 10, 2006, 7:25am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/83 "2006-04-10T07:25:01Z")
> [@Sam Stone](#): > > Blake, I think you’ve become unreasonable here. Well, I think he’s given up on this thread as it wasn’t going his way - at any rate, I’m still waiting for his return shot in our game of Citeball… ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 10, 2006, 11:44am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/84 "2006-04-10T11:44:15Z")
Geez – is this _still_ goin on? A lot of these points are ridiculous – On filling buildings with mud: the entire _city_ of Herculaneum was filled with mud. A river of it swept through the town, just as it did down the side of Mt. St. Helens. Preserved the buildings perfectly without collapsing them, and they were built of stone. (Pompeii was buried by ash, and its buildings, for the most part, didn’t collapse, either). Much flimsier buildings can be preserved in mud, too. When I lived in Utah there was town you could see the remains of. It had been buried in mud during a flood, and the tops of the houses were still visible above the dirst – it was as if the flood had come through and the water had miraculously turned to solid earth in the houses (which isn’t too far off the mark of what happened). As for towns being buried, see my much earlier statements about Ostia and Glanum. Ostia silted up (but the walls and even the wall paintings were prweserved). Ostia, too, was buried. I don’t know the precise process, but it wasn’t anything catastrophic like an eruption. ---
**Author:** ![Steve\_MB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steve_mb/32/5339_2.png) [@Steve\_MB](https://boards.straightdope.com/u/Steve_MB)\ **Post date:** [April 10, 2006, 2:30pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/85 "2006-04-10T14:30:21Z")
> [@Sam Stone](#): > > Most stuff in low earth orbit will decay in a relatively short time - if we stop launching stuff into space, almost all of it will have come back to earth within a few hundred to a few thousand years. I’m not sure how long some of the geostationary satellites will last - maybe a long time. The LAGEOS ones I mentioned are intentionally places in an ultra-stable orbit, so I would guess that they will be the longevity champs. The OP already disallowed artifacts on the moon. The LAGEOS satellites orbit about 5800 km above the surface. Geosynchronous orbit is considerably higer (about 36000 km about the surface). Geosynchronous orbits aren’t going to decay anytime in the next few million years, but they might be far enough out that satellites would eventually be perturbed into an orbit sufficiently elliptical to allow escape or eventual burnup. ---
**Author:** ![elmwood](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmwood/32/3060_2.png) [@elmwood](https://boards.straightdope.com/u/elmwood)\ **Post date:** [April 10, 2006, 3:51pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/86 "2006-04-10T15:51:13Z")
How about road cuts through mountains and hills in areas outside of glaciation? Grading from Interstate highway rights-of-way in the US Southwest? The sudden beginning of high water marks in canyons upstream of the former location of a dam? ---
**Author:** ![EllisDee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ellisdee/32/4531_2.png) [@EllisDee](https://boards.straightdope.com/u/EllisDee)\ **Post date:** [January 21, 2008, 8:43pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/87 "2008-01-21T20:43:42Z")
I know this thread is old, but I think this bump is justified to let all the participants know that the History Channel is doing a show on this very topic. [Life After People](http://www.history.com/shows.do?action=detail&episodeId=262869) will first air tonight at 9:00pm Eastern, and then will be rebroadcast several times throughout the week. (Air times listed in the link.) ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [January 21, 2008, 8:47pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/88 "2008-01-21T20:47:31Z")
I’ve been waiting for weeks for this show to come out. I’ll definitely be watching it tonight! -XT ---
**Author:** ![treis](https://avatars.discourse-cdn.com/v4/letter/t/bc79bd/32.png) [@treis](https://boards.straightdope.com/u/treis)\ **Post date:** [January 21, 2008, 9:49pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/89 "2008-01-21T21:49:42Z")
I’m surprised no one mentioned Cheyenne Mountain. It’s obviously man made, and likely will be there as long as the mountain is. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [January 21, 2008, 10:12pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/90 "2008-01-21T22:12:18Z")
I think in the original OP it was said that only things you could see laying about (i.e. that some alien species coming to earth would stumble over without having to dig). It’s been a while since this thread was up and I don’t feel like going back through it. 🙂 -XT ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [January 21, 2008, 10:55pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/91 "2008-01-21T22:55:16Z")
[QUOTE=xtisme] well, probability is a strange beast. [/quote] True that. It occurs to me that the destruction would be a somewhat stochastic process. For example, suppose that there is a structure that one can expect to last 500,000 years before it gets subducted or whatever. Well, there is a small chance that the same structure will last 600,000 years, 700,000 years or even 2 million years. Given that there are millions of man made structures in the world, it seems likely that a few will stay recognizable long after their shelf life has expired. ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [January 22, 2008, 1:40am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/92 "2008-01-22T01:40:00Z")
Given the number of signals we have sent (by Frank Drake in '74 for example), it seems likely that an advanced civilization could easily detect the previous location of Earth even if it was destroyed by some irreversible process. WAG. IANAP. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [January 22, 2008, 4:11am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/93 "2008-01-22T04:11:06Z")
Well, that was depressing. Life after Humans gave the vast majority of our civilization less than 500 years…and pretty much (according to them) nearly every trace of humans would be gone after 1000. They rate Mt Rushmore as the most probable structure to survive for any real length of time (the one guy said something like 100k-300k). -XT ---
**Author:** ![SSG\_Schwartz](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@SSG\_Schwartz](https://boards.straightdope.com/u/SSG_Schwartz)\ **Post date:** [January 22, 2008, 4:18am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/94 "2008-01-22T04:18:06Z")
I didn’t really understand why NYC would become a jungle while Seattle would look like a crumbled city for a lot longer. SSG Schwartz ---
**Author:** ![treis](https://avatars.discourse-cdn.com/v4/letter/t/bc79bd/32.png) [@treis](https://boards.straightdope.com/u/treis)\ **Post date:** [January 22, 2008, 4:30am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/95 "2008-01-22T04:30:31Z")
[QUOTE=xtisme] Well, that was depressing. Life after Humans gave the vast majority of our civilization less than 500 years…and pretty much (according to them) nearly every trace of humans would be gone after 1000. They rate Mt Rushmore as the most probable structure to survive for any real length of time (the one guy said something like 100k-300k). -XT [/QUOTE] I stopped watching it when they said London would flood because the sea-wall would no longer be operational. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [January 22, 2008, 4:32am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/96 "2008-01-22T04:32:05Z")
I notice they didn’t really talk about what cities like Las Vegas or Phoenix would look like either…they concentrated mostly on New York with a couple of bones thrown in about Chicago (there would be a fire), Seattle (the Space Needle would fall over), Rome (it would burn again) and Paris (the Eiffel Tower would fall over)…with a lot of the rest of the show talking about the Hoover Dam (it would be one of the longest lasting structures in North America…according to the show). -XT ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [January 22, 2008, 6:33am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/97 "2008-01-22T06:33:47Z")
As for discovering evidence a million or more years on, I think the erosion argument is compelling: A great deal of the trillions of tons of human artifacts will be buried. The processes that bury also reveal. It passes all probability that this sort of geological “churning” would not regularly reveal durable objects like arrowheads, ceramics, gravestones, etc. ---
**Author:** ![treis](https://avatars.discourse-cdn.com/v4/letter/t/bc79bd/32.png) [@treis](https://boards.straightdope.com/u/treis)\ **Post date:** [January 22, 2008, 6:46am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/98 "2008-01-22T06:46:48Z")
[QUOTE=xtisme] I think in the original OP it was said that only things you could see laying about (i.e. that some alien species coming to earth would stumble over without having to dig). It’s been a while since this thread was up and I don’t feel like going back through it. 🙂 -XT [/QUOTE] I see no reason why the entrances would be covered up. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 22, 2008, 9:58am UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/99 "2008-01-22T09:58:05Z")
If tectonic activity eventually recycles the whole of the Earth’s crust, that would do a fairly good job of erasing our traces, although it probably wouldn’t ever be complete, as some objects will be moved about and deposited/eroded out/redeposited in sedimentary formations, away from the subduction zone. So, barring some anomalous event such as collision with a rogue planet large enough to melt the whole Earth, I think we’ll have to wait until the sun expands and wipes the slate clean. ---
**Author:** ![alphaboi867](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alphaboi867/32/3898_2.png) [@alphaboi867](https://boards.straightdope.com/u/alphaboi867)\ **Post date:** [January 22, 2008, 9:02pm UTC](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228/100 "2008-01-22T21:02:12Z")
[QUOTE=alterego] Given the number of signals we have sent (by Frank Drake in '74 for example), it seems likely that an advanced civilization could easily detect the previous location of Earth even if it was destroyed by some irreversible process. WAG. IANAP. [/QUOTE] One of the talking heads said that those signals would decay so much that they couldn’t be detected as something other than “noise” after only a light year or two. :dubious: [Previous page](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228.md?page=4) [Next page](https://boards.straightdope.com/t/how-long-would-it-take-nature-to-destroy-the-evidence-of-human-existence/351228.md?page=6)