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Author Topic: Why does the world sink over time??  (Read 3195 times)

bigfella

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Why does the world sink over time??
« on: October 19, 2008, 09:31:53 AM »

One of the things that has always puzzled me (besides the meaning of life) MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM why are we here??  ?? ?? ?? ?? ?? Sorry just went off for a moment. But seriously this is one for the archaeologists amongst us. Why are the buildings and artifacts that are dug up in archaeological digs so deep under the soil?? Is it because after so many years they have sunk. Is it that the air bourne dust and dirt has slowly accumulated over the years and covered it?? If it is either of these will we see some of the taller building from a hundred years or so be a storey shorter in the next hundred years.

Just curious ????

Regards David
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Colin Bishop

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Re: Why does the world sink over time??
« Reply #1 on: October 19, 2008, 10:23:58 AM »

David,

There are a lot of reasons, although if you watch “Time Team” you will see that a lot of stuff is in fact only just under the surface. Most commonly, if you have a site which has been occupied for thousands of years, each generation builds on top of the one before so the city actually rises above the surrounding landscape on a mound with the oldest remains at the bottom. Examples of this are the sites in Mesopotamia (Iraq) and Troy.

The Mediterranean is very active tectonically with lots of earthquakes and volcanoes so things either get shaken to pieces or covered in volcanic ash. At Mycenae in the Peloponnese and Phaestos in Crete you can see where part of the site has crumbled away and fallen down the hill as a result of earthquakes. On the island of Santorini the ruins are buried under hundreds of feet of ash and are well preserved – see pic. Along the Aegean coast of Turkey you can see underwater ruins from glass bottom boats where the land level has dropped or sea levels have risen. Go to Egypt and the old temples have been preserved by being covered by encroaching desert sand. In South America the jungle has taken over and covered the remains in organic detritus. In my back garden, the flowerbeds are higher because my wife insists on planting each year’s new lot of daffodils under more bags of compost from the garden centre! Things change all the time although it’s not always apparent over a human lifespan unless you have a catastrophic event such as Pompeii. In Edinburgh there are streets below the existing streets which have been sealed off and built over since the middle ages. I believe you can visit some of them.

There was a report recently that said if the human race suddenly ceased to exist, within 50,000 years there would hardly be any visible trace of our being on the planet. Quite intriguing as there are plenty of free 50,000 year slots since the age of the dinosaurs when civilisations would have been able to appear and vanish!

It's all fascinating stuff - one of my "other" hobbies.

Colin
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bigfella

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Re: Why does the world sink over time??
« Reply #2 on: October 19, 2008, 12:32:54 PM »

Thanks Colin, I have always been interested in this type of thing although I have never taken it any further. I find Time Team a great show and wonder what happens to the digs after the alloted time taken for the show?? I take it that you have been on a dig or two which must have been fantastic and I would like to hear some of your finds.

It does make you think that are we just going on a merry-go-round of building up a civilisation and then it dissapearing and then starting up another and so on.

Regards David
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Colin Bishop

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Re: Why does the world sink over time??
« Reply #3 on: October 19, 2008, 01:08:49 PM »

I've not been on a dig myself. Just like the subject, reading about it and visiting ancient sites. The underground passage entrance in the picture above is at Mycenae. It passes under the ramparts and down 18 metres to an underground water supply and was built around 1200 BC. There is no lighting and the stairs are steep and slippery with a dog leg half way down. In the UK it would be closed off by 'elf 'n safety but the Greeks are more laid back about that sort of thing. It's quite an eerie experience to descend into the bowels of the earth on a stairway that was used by the Homeric heroes. If he existed, King Agamemnon would have used these steps which are over 3,000 years old.

I also find it amazing that the Minoans had flushing toilets 3,500 years ago. But curiously, despite all the pottery that has been uncovered nobody has found anything that can be definitely identified as a chamberpot!

Always something new to learn.

Colin
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Peter Fitness

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Re: Why does the world sink over time??
« Reply #4 on: October 20, 2008, 01:24:12 AM »

Colin, I remember being in Monmouth in 1993, walking down the street, when we had to divert around some work being carried out on one of the shops. On closer inspection, we found that workmen had unearthed the foundations of some Roman buildings about 10 feet below the current street level. The ruins included some quite sophisticated drainage systems. Apparently, the shop owners had agreed to keep the shop closed to give archaeologists time to assess and catalogue the finds.

I found this fascinating, mainly because we have nothing like that here in Australia. While the Aborigines are thought to have been here for at least 60000 years, they were nomadic, and left very few indications of their presence apart from some wonderful rock art. We also visited the Roman villa at Chedworth, Gloucestershire, on that trip, while in 1997, we saw the Roman ruins at Wroxeter in Shropshire.

Peter.
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Roger in France

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Re: Why does the world sink over time??
« Reply #5 on: October 20, 2008, 05:43:39 AM »

Even more recently than the examples given are sinking caused by man.

In parts of Cheshire where indiscriminate salt mining used to take place, there are several examples of where land, roads, even houses have sunk because too much salt was washed out underground. Today there is much more control over mining. Salt was/is extracted both by forcing water down bore holes and collecting the saline solution which came back up but also by actual mining. I have been in caverns which could comfartably house St Paul's Cathedral!

There is even a formal Salt Mining Subsidence Board which pays compensation.

Roger in France.
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Bunkerbarge

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Re: Why does the world sink over time??
« Reply #6 on: October 20, 2008, 09:25:19 AM »

I think it is important to consider the concept of why we percieve things to be 'sinking'.

The world is obviously ever evolving and this means that lands masses are continuously shifting by any one of a number of different mechanisms, some natural and some man made.  This shifting though can be either the depositing or the erosion of land mass over time so if we imagine areas that have been subjected to erosion the land mass, including any ancient remains and artifacts will equally be eroded and removed.  On the other hand deposits will cover over other areas so the evidence of earlier civilisations will be covered and, obviously, will be the only ones available for future generations to discover.

It is obviously a great shame that much evidence located in areas of erosion have been lost forever but we shouldn't forget that it was there in equal proportions to the evidence left to us buried under deposits.
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malcolmfrary

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Re: Why does the world sink over time??
« Reply #7 on: October 20, 2008, 02:14:33 PM »

At "our" lake, Fairhaven, a few years ago we persuaded the council to extend the paved launching area.  Old (30 years ago) pictures show the grassed area from the park path to the lake side as being level, but to pave it the grassed area had to be dug down to a depth of about 15".  Looking at the small cliff thus formed, strata were visible - dark, sand, dark, sand.  I took the dark to be the result of guano-assisted plant life of summer, and the sand as, well, sand, having been blown in from the Ribble estuary over the winter and trapped by the grass.  Presumably the sand was scenery worn away from somewhere else, deposited on the beach and subsequently blown back onto land.  This sort of thing could go on world wide.
The old artifacts are not really sinking, everything else is building up.
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dreadnought72

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Re: Why does the world sink over time??
« Reply #8 on: October 21, 2008, 10:27:34 AM »

Peter's experience sounds about right.

I was an archaeologist back in the early eighties. I dug parts of Roman Carlisle up, and most "surfaces" - including a corner of a fantastic cobbled byre floor, which took many hours and a pickaxe to lift - were 6-10 feet down. For northern European cities this seems to be about typical, and the build up is soil, old rubble and all the usual waste. We got some great leather work perfectly preserved, along with wooden items where you could still see tool marks (the subsoil was a heavy clay, near the river Eden, and invariably soaking - perfect conditions).

For non-urban sites findings are usually much shallower: a dig I was on of an Iron-Age site in Wales revealed features that were about 1-2 feet underground. When you think of two millenia of seasonal plant growth and decay it felt about "right" in terms of the build-up. The Roman Fort at South Shields, situated on top of an exposed hill, was equally shallow. The risks here, of course, are that easily exposed and well-cut Roman stone would be lifted for later re-use, and at shallow depths ploughing can wipe out a lot of information.

Andy, BA Hons (Newcastle University 1984) - still found sneaking looks at holes-in-the-road.  ;)
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Reade Models

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Re: Why does the world sink over time??
« Reply #9 on: October 21, 2008, 02:37:49 PM »

In parts of Cheshire where indiscriminate salt mining used to take place, there are several examples of where land, roads, even houses have sunk because too much salt was washed out underground. Today there is much more control over mining. Salt was/is extracted both by forcing water down bore holes and collecting the saline solution which came back up but also by actual mining. I have been in caverns which could comfartably house St Paul's Cathedral!

Roger in France.

I spent the first half of this year designing instrumentation and telemetry systems for the brine fields at Holford, just south of Northwich where I live.  The brine boreholes which produce the feedstock for the Chlor-Chem process plants at Runcorn are  still very much in use.  New boreholes are being brought on-line all of the time and have a 25 year productive life on average.  The brine is pumped overland from Northwich to Runcorn.

Disused boreholes are now being converted for gas storage - by Eon and Gas de France, though why British companies can't do this is beyond me?  These gas storage facilities will accept the high-cost gas that the UK imports from eastern Europe, and the French will then charge the UK an additional premium for storing it on UK territory!

All rather confusing...

Roger is absolutely correct about subsidence, there used to be a series of old photographs on the wall behind the cash registers in Tesco's at Northwich showing lots of houses that had sunk into the ground almost to roof level!  Some had sunk in at crazy angles leaving parts of the foundations sticking up in the air!

Malc




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tigertiger

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Re: Why does the world sink over time??
« Reply #10 on: October 21, 2008, 03:37:52 PM »

From a geological perspective, some parts of the world are going up (uplift) some parts are going down.

Some parts are being burried by aluvial flow (river seidments); and other parts are being eroded by wind and water.

The bits that are bing burried or going down are where the history is under the surface.

The bits that are going up are up a mountain like mount Ararat. Or being those being eroded are 'above the surface'; i.e. already gone.
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JayDee

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Re: Why does the world sink over time??
« Reply #11 on: October 21, 2008, 04:32:11 PM »


Hello,

 What about the ancient tracks in the South American desert, in Chile I think.
Those tracks have been there for thousands of years and yet they are still on the surface, where they have always been.
Next to no erosion, no sinking, they look as if they are new - - - and no one knows who or why they were made !!.
More visible from Space, than on the land, they are a real enigma.

John.   8)
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Bee

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Re: Why does the world sink over time??
« Reply #12 on: October 22, 2008, 09:37:01 PM »

In verdent places such as the uk worms will move soil from under an object, grass will grow over the top, die rot and become part of the soil. This only happens in the topsoil so things sink down about a foot until they hit the subsoil and stones. Here and there bigger animals, humans etc stir things up enough to bury further. Anything that does stay above the ground, like castle walls, gets robbed by humans. Post holes, ditches etc get filled by small scale erosion.
In many 'ancient civilisations' they had no cement so built walls etc out of stone and mud/dung to bond it. This sort of unstable construction naturally falls apart after a few decades, if that. So when renewal became inevitable the larger stones would be recovered and the mud and smaller stuff just got levelled out - maybe a foot or two increase in level. What's more if several of your neighbours did this you ended up as the lower point for the rain to flood so there was an incentive to follow suit.
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bigfella

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Re: Why does the world sink over time??
« Reply #13 on: October 25, 2008, 06:50:07 AM »

While the Aborigines are thought to have been here for at least 60000 years, they were nomadic, and left very few indications of their presence apart from some wonderful rock art.

I agree Peter. However one of the other significant things left behind by Aborigines are the massive Middens. Some are huge and have been found to been used seasonally when shell fish were plentifully in that area for hundreds of years. Although nomadic they had regular areas that they would visit and follow the food cycle. To a lesser extent some of the Bora Rings have remained for many years. The Bora Ring was a sacred place where a coming of age ceremony took place. They are a hardend depression in the ground which is banked round the side and was a place only for men.

Regards David
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Colin Bishop

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Re: Why does the world sink over time??
« Reply #14 on: October 25, 2008, 10:14:46 AM »

Is it true that the whole of Australia has sunk, just leaving Ayers Rock sticking up in the middle?  %)
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bigfella

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Re: Why does the world sink over time??
« Reply #15 on: October 25, 2008, 11:12:38 AM »

Is it true that the whole of Australia has sunk, just leaving Ayers Rock sticking up in the middle?  %)

The global warming lot would have you believe that. However Our PM has a $10million seaside mansion, the Environment Minister also has a mansion on Sydney Harbour and they are the 2 most strongest supporters of AGW. You would think if you truly believed that the sea will rise by so much from global warming as they say, you would live on top of a mountain. Just another thing that politicians use to scare the masses into supporting them. It is just hypocrisy.

Regards David
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cbr900

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Re: Why does the world sink over time??
« Reply #16 on: October 25, 2008, 02:41:16 PM »

If global warming is to be believed then if anyone else happens to follow
MotoGP they will also have noticed that this year when we will have a lot less
rain, that the MotoGP championship has had 1 clear round without rain in 19 GP's
if thats global warming I'll eat my hat, MORON politicians will tell you anything..........


Roy
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Peter Fitness

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Re: Why does the world sink over time??
« Reply #17 on: October 25, 2008, 10:10:03 PM »

Colin, I think a lot of inland farmers would like to see some water around Ayers Rock, sorry, Uluru (The Aboriginal name).

Roy, the "experts" tell us it is not so much global warming, rather it is climate change. In other words, some areas can experience unusually high rainfall, and others will have significantly less. While I am sure that mankind has affected the weather, I believe that weather patterns are cyclical as there is plenty of archaeological evidence of much higher sea levels in past times.

Well, I'd better turn my computer off now, to do my bit towards saving the planet.  :-))

Peter.
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Roger in France

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Re: Why does the world sink over time??
« Reply #18 on: October 26, 2008, 06:04:34 AM »

I am just re-reading Charles Darwin's "The Voyage of the Beagle". At several points he comments on sea and land level changes and uses such evidence in formulating his ideas, which he later puts into "The Origin of the Species".

Roger in France
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bigfella

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Re: Why does the world sink over time??
« Reply #19 on: October 26, 2008, 09:14:25 AM »

You are right Roger. The world is constantly changing and always has. The sea level also has gone up and down over the life of this planet. However the climate change religion disciples try to tell us that it is us humans who have done it all. Oh and what happened to no ice this year in the North Pole???

Certainly I agree that we should clean up our act. However where does the science end and guess work start in these scientists modeling. It is all "computer modeling" and as we all know computers only give you the result of what you put in it.

Said my piece on this, now back on topic.

Regards David
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Admhawk

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Re: Why does the world sink over time??
« Reply #20 on: October 28, 2008, 11:28:03 PM »

This is all fascinating! And here I thought it was just because we were all getting fatter.  :o %% O0
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