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In reading various bits of history relating to the time period of RTW etc I keep seeing references to the fact that the Mediterranian rose several meters during the rise & plateau of Rome and has since lowered but is still 2M or so above what it had been.
Does anyone have the faintest idea why this is?
I'd really like to at least know what some theories are.
Well since the last Ice age (wich ended around 10000-11000 years ago)The average temp has kept rising.so less water is locked up as ice=rise in sea level's.I believe at the height of last ice age(18000 years ago) the sea level was upto 50 meters lower than today!Imagine being able to walk to france from britain without a boat! ~:eek:
It could be caused by natural climate fluxes the Earth goes through. These risings and dips in the temperature affect how much water gets stuck in glaciers. The hotter it is the more water there is in the ocean and the cooler it is the reverse occurs.
Such a gradual global temperature shift was happening in the 17th century that aided population growth all over Eurasia due to improved harvest sizes and increased resistance to diseases.
I don't know anything specific for certain about the mediterranean rising or lowering by 2 m though. 2m seems drastic for under 900 years to me anyways.
However, a vertical increase of a several inches could translate to a horizontal increase of a few metres, depending on the slope of the land. As well plate tectonic activity can raise and lower landforms, which could cause bodies of water to gain or lose surface area. For instance the tectonic plate that Britain and the Netherlands(along with a whole lot else) are on is rising in the north of Britain which is causing the Netherlands to dip (they've been fighting ocean encroachment for centuries:thinking2: ). The Netherlands are thus facing rising ocean levels so to speak which is something serious for such a low lying country, unlike Britian which has much hillier and higher land.
It is believed this rising of northern England is caused because that area is still recovering from having megatons of ice on it from the last ice age. Those things are fricken heavy after all and tectonic plates take a long time to adjust. At some points glaciers during the ice age were several kilometres thick! :stunned:
So getting back to the mediterranian it is possible that Rome rose during rising global or perhaps continental temperatures. I suppose the tectonic plate thing wouldn't really apply to such a short period of time, but I find that stuff interesting anyways. :book:
I hope some other people have some ideas too, hope you find some useful info! ~:cheers:
The iceage is one reason for land to rise yes. Sweden grows bigger every year, rising because the ice (3 kilometres thick) had pressed it down and now it rises beacuse the enourmus weight is gone.
Another explanation for rising/lowering of land are tectonics(??) and vulcanism.
Im no expert on these matters but for answers you should look to information in subjects geology, geography and so on.
Kalle
Nodachi beat me to it with a small margin ~:cheers:
Kalle
Quote:
Originally Posted by Jediknight73
That was very efficiently said, lol. Yea I remember that there was a landbridge between Britain and Europe during the ice age. Maybe 2 metres isn't so drastic for just 900 years.
I’m not an expert on this either, but there is such thing as "mini-ice ages" and following periods of time when things warm up depending on natural tilting of the Earth. This is one of the reasons for the Vikings to come pouring out of the north. In the 800's the temperature warmed up and the population exploded in Scandinavia due to the new availability of food. Only problem is that there isn't very much room to live in that region. The fluctuation in water level is tied to these global changed in the Earths temperature. If memory serves, Napoleon happened to attack Russia in 1812 during one of these mini-ice ages. That and some crazy other natural coincidences made that winter one of the coldest in recorded history.
Although that really doesn't apply to the original question, it’s a good bit of history. I may be wrong though.... anybody else want to discuss the weather?
Haha, indeed. Its cool to see others have the same idea as I do. Everyone seems to say things more consisely than me too lolQuote:
Originally Posted by Kalle
This stuff is all well & good & generally fits with my thinking.
But I just can't get over this bit:
There is clear archaeological evidence that 2M or so is only the current difference between now & the early Roman mediterranean sea level.Quote:
2m seems drastic for under 900 years to me anyways.
At the peak the level was substantially higher than it is now.
eg http://www.salt.org.il/arch.html
http://www.salt.org.il/palg.html
http://www.salt.org.il/chart2.gif
This is marked in years before present (1962)
You can see that from early Roman Republic ~400BC to late Empire ~500AD there is just about a 4M sea level rise :eeeek:
That site seems to link it with global changes based on volcanic ash on Antarctica.
I did a bit of palaeoclimatology at university (module during Geology BSc a few years ago). Unfortunately I didn't look at anything that recent, but the Mediterranian Basin has been subject to numerous drying and flooding events, the most recent being about 5 million years ago. Then the Atlantic would have come pouring in over the straits of Gibraltar, relatively rapidly filling the Mediterranian (and much more recently maybe only a few thousand years ago, the Black Sea) When dried the Mediterranian would have been an extremely hot desert, with perhaps a saline lake, similar to the dead sea in the middle.
Even under relatively normal conditions, the level of the Mediterranian can sometimes be slightly lower than global sea level, as it is a relatively isolated basin, affected by evaporation as well as flow from the Altantic. A 2m difference in Mediterranian level does not necessarily mean a 2m difference in global sea level.
There's I suggest having a look at the Geology section a little way down the page here for more info: http://encyclopedia.laborlawtalk.com/Mediterranean_Sea. It's just the first one I pulled off google that wasn't either an Atlantis or Biblical Flood site (The last Mediterranian and Black Sea flooding events get related to both).
This isnt the easiest of data to interpret at all and not helped by a lot of axe-grinding going on about climate change. One problem is that the land doesnt stay still either, and tectonically active areas like the med are not good places to pick up global features. Mediterranean subsystem effects needQuote:
Originally Posted by hoom
correlations from lots of sites to make an accurate picture. Results from passive margins like Eastern USA are better indicators (see http://www.state.me.us/doc/nrimc/pub...e/sealevel.htm )
To complicate matters you also have glacioeustatic change. Basically after you remove the weight of the ice off a continent, then the land rebounds up
so sealevel 6000 years was in places higher than present.
http://www.homepage.montana.edu/~geo...2/texteust.htm
explains some of this.
Ports that are now far from sea are often about silting up rather than sea level dropping, but an earthquake or two helps as well.
In short, though to have 2m of change in 1000 years implies local tectonic effects to me.
I agree. I read through some of this a few days back because I was curious. Changes in level of that magnitude don't appear to be all that uncommon in places where the plates come together, like the Med. There is a lot not yet understood about plate tectonics and vulcanism. And there is very little known about how the Earth's magnetic field is generated or how the earth's core is structured. A number of generally accepted theories, but in reading them they all tend to swallow massive inconsistencies. Wouldn't surprise me to see them turned on their ears within a decade or two.Quote:
Originally Posted by scaddenp
While doing geology at university we were using a textbook written by one of the lecturers only written a few years ago. They were good enough to tell us in the lecture that one of their 'pet' theories on the structure of the earth's mantle, covered in detail in the book, had been comprehensively disproven in the light of new evidence.
While plate tectonics is an almost universally accepted theory, a lot of the details have a long way to go.
Isostatic and tectonic change of landmasses have, however, been directly observed with surveying and sattelite technology, as have evaporites and sediments inidicating changes of sea level in the Med. The theories can change but the basic observations don't.