Some deep archeaological thoughts...
Neil Barnes
city and park a glacier on top of it for a thousand centuries?
I'm at the stage where the climate is beginning to warm up a
little and the ice is moving back. It's also getting wetter -
less water locked up - so the places things grow are changing,
and there is associated population pressure moving people around.
Sea level is probably rising, too.
I need:
o A place of legend, so that my rude mechanicals can be
frightened of its exposure.
o A reasonable chance that a passing time traveller (ok, he's
spent a lot of time at nearly lightspeed) might expect to find
something useful in the wreckage.
It seems that I *don't* want to *roll* a glacier over it - or I'd
have a spectacular U-shaped valley instead of wreckage, so I'm
wondering about something right on the edge of the icefield. I
have had places of similar age turning up in a very delapidated
condition in deserts, for example, so people wouldn't be
surprised that there's something there. One thing - by the time
the ice age arrives, there aren't any people in a condition to
worry about preserving the city.
Cheers,
Neil
jhetley
"Neil Barnes" <nailed_...@hotmail.com> wrote in message
news:ahet1p$slci1$1...@ID-123172.news.dfncis.de...
><snipped>
> It seems that I *don't* want to *roll* a glacier over it - or I'd
> have a spectacular U-shaped valley instead of wreckage, so I'm
> wondering about something right on the edge of the icefield. I
> have had places of similar age turning up in a very delapidated
> condition in deserts, for example, so people wouldn't be
> surprised that there's something there. One thing - by the time
> the ice age arrives, there aren't any people in a condition to
> worry about preserving the city.
>
My first reaction goes along with that lead sentence -- just spent a few
hours bicycling around the results of the last ice age. Bare rock, with
random deposits of sand and gravel where the meltwater floods left them.
I think you'll have to choose your city carefully. Things under the bottoms
of glaciers aren't going to survive, and most cities are in relatively low
areas. Even those at higher altitude tend to be in valleys.
On the other hand, things that go into the _tops_ of glaciers tend to come
out sort of recognizeable, after a few decades or centuries. Witness the
Ice Man, and that WWII passenger aircraft that they found recently in the
Andes.
What do you need your time-traveller to find?
--
Jim
THE SUMMER COUNTRY, by James A. Hetley: a novel of dark contemporary
fantasy
Coming in October 2002 from Ace Science Fiction & Fantasy
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Dorothy J Heydt
Neil Barnes <nailed_...@hotmail.com> wrote:
>Or, to put it another way, what happens if you take a major C20
>city and park a glacier on top of it for a thousand centuries?
You might wish, or then again you might not wish, to
take a look at Poul Anderson's _The Winter of the
World._
He has (a) cities that have been inhabited more or less
since before the Ice came; (b) lots of stuff that has
been buried under the Ice that people can't get at, and
... (c) one city whose inhabitants tried to protect it
from the Ice for a very long time, so that it's still
partially accessible, and people go to it occasionally
to try to salvage things.
Dorothy J. Heydt
Albany, California
djh...@kithrup.com
http://www.kithrup.com/~djheydt
Charlie Stross
as <nailed_...@hotmail.com> declared:
> Or, to put it another way, what happens if you take a major C20
> city and park a glacier on top of it for a thousand centuries?
> I'm at the stage where the climate is beginning to warm up a
> little and the ice is moving back. It's also getting wetter -
> less water locked up - so the places things grow are changing,
> and there is associated population pressure moving people around.
> Sea level is probably rising, too.
Hmm.
Sea levels may actually _sink_ relative to the land masses. The whole
of Scandinavia is rising at a rate measured in inches per century, and
has been for about 12K years since the end of the last ice age -- the
mass of an ice sheet roughly 2km thick has been removed from on top of
it, and the whole land mass is rising slightly.
Again, remember that about 80% of the human population lives within 100Km
of coastlines.
So it's possible that during your just-passed ice age several coastal
cities will have been dunked in the sea, and now they're surfacing again.
On the nature of modern construction: we rely heavily on reinforced
and pre-stressed concrete. Pre-stressed concrete is interesting stuff;
it owes its structural integrity to steel rods threaded through it. As
it ages, it's prone to two processes. Firstly, the steel is liable to
slowly rust away. This won't be significant in less than a century or
three, and modern steels used in reinforced concrete are especially
resistant to it, but after a thousand years or more it's liable to be a
drastically noticable process -- not to put it too bluntly, most of the
tall buildings or deep foundations will have lost their reinforcement. On
the other hand, as concrete ages it slowly undergoes chemical reactions
that produce something not unlike limestone as the end product. But
melting glaciers release lots of water that corrodes limestone ...
... So my guess is that your largely-concrete city, crumbled under an ice
age, will (unless it's submerged) end up resembling a very weird limestone
pavement -- horizontal slabs of limestone and aggregates, pretty thin in
most places but with really thick bits where skyscrapers have collapsed,
laced with iron-rich sandstone and sediments, and subject to the erosive
forces that produce bedding planes and limestone caves and grottos below
the surface (where it's thickest). After ten to fifty thousand years, I
wouldn't be surprised for multi-megaton skyscraper developments to be most
visible as overgrown limestone cliffs with pot-holes and grottos.
Once we get into deep time -- megayear territory -- the asphalt paving
and plastic in landfills will slowly be compressed (especially once
continental drift begins to drag them down into subduction zones) and
end up bubbling up in the form of new petrochemical deposits; oil wells
and gas fields. (We tend to forget that new fossil fuels can form as
the fossilization process continues -- we don't destroy the stuff forever,
just for the merely human time-spans we think in terms of.)
Stuff that's going to persist: some plastics -- not polyethylene
based, which tends to degrade under UV light, but really long-lived
stuff. Carbon fibre composites? No, they're usually held together by a
resin matrix. Most refined metals will oxidize over time, as well. But
ceramics are a good bet for long-term recognition, and our society
makes a lot of them. Expect to see some recognizable pot-shards in the
aggregates and gravel and what-not around the limestone pavements. Also
expect weirdly-shaped lumps of metal ore -- rectangular chunks, for
example, which would normally be rare in nature, where cars or trucks
were abandoned. Maybe with engine-block sized nuggets embedded in them.
Hmm. Refractory metals. Will the tungsten wire filaments in light bulbs
survive? (They're tough and very resistant to oxidation and evaporation.)
Oh. One other type of relic might survive: see my weblog (scroll down a
way) for a close tour of a civil nuclear reactor (actually the AGR
complex at Torness). I'm pretty confident that _that_ thing would survive
intact, if abandoned for several hundred years, and the reactor itself
would be recognizable as a vast technological artefact even after some
thousands. (We're talking about a lump of metal weighing several thousand
tons and held together with steel cables and bolts to survive earthquakes,
tidal waves, or the direct impact of a 747 with full fuel tanks flying
at cruising speed.)
-- Charlie
Out now: "Toast, and other rusted futures" -- available via my blog
http://www.antipope.org/charlie/blosxom.cgi
Jonathan Hendry
"Charlie Stross" <cha...@antipope.org> wrote in message
news:slrnajm84s....@raq981.uk2net.com.antipope.org...
> ceramics are a good bet for long-term recognition, and our society
> makes a lot of them. Expect to see some recognizable pot-shards in the
> aggregates and gravel and what-not around the limestone pavements.
In some locations, there won't be many pot-shards, but there might
be CPUs and other ICs, or at least their ceramic packaging.
"We worship the great Motorola"
Tim S
<snip further useful details>
It also makes a difference which way erosion is going. Is your city exposed
and eroding away or is it getting covered in sediment and being buried? Is
it exposed to wind and/or waves? Rivers? I'd expect annual flows of glacial
meltwater, probably depositing a fair amount of silt and pebbles, and
possibly huge floods toward the end if the glaciers retract quickly.
If the glacier reaches your city and stops there, it'll leave behind a huge
amount of miscellaneous debris when it retreats. If it goes over your city,
it'll scrape it away and dump it in bits all over the place.
Repeated freeze-thaw cycles will also tend to erode your city more rapidly.
Tim
scifi...@no-spam.org
> have a spectacular U-shaped valley instead of wreckage, so I'm
> wondering about something right on the edge of the icefield. I
> have had places of similar age turning up in a very delapidated
> condition in deserts, for example, so people wouldn't be
> surprised that there's something there. One thing - by the time
> the ice age arrives, there aren't any people in a condition to
> worry about preserving the city.
What about the very thing that creates glaciers in the first place... snow.
After it reaches a certain depth it compacts into ice and eventually becomes
part of a glacier, possibly in the center of the city itself. But instead of
boulders, it would (temporarily) have buildings in it. Of course once the
mass reaches a certain point, it will start moving... moving... moving...
thanks,
g.m.
Neil Barnes
news:rhx%8.575$Ky3....@newsread2.prod.itd.earthlink.net:
I wondered about that - a little plot fiddling means I can cope
with the city endup largely as terminal moraine, and what glacier
there is scraping nearly down to a deep-rock hidey-hole.
Neil