I just spent some time investigating Egypt, and several other ancient peoples.
I didn't go to creation, YEC or radical evolutionist sites, so all the references assumed there was no flood as is the common opnion.
Likewise I will not accept a biased sites data, so if you give a response from a site which exists for the sole purpose of proving or disproving something, dont expect me to be impressed.
The best chance for defining a civilization before the flood is the Egyptian Pyramid Giza.
I did some research on the Egyptian Pyramid Giza and I did find some dates that refered to 2500 BC at this site.
http://www.archaeology.org/9909/abstracts/pyramids.html
But there is more to it than that.
The site indicates that the readings were taken twice once in 1984 and once in 1995 with a 200 year discrepancy between there averages of the two attempts.
Also under the "1984 Results" it states
The 1984 radiocarbon dates from monuments spanning Dynasty 3 (Djoser) to late Dynasty 5 (Unas), averaged 374 years older than the
Cambridge Ancient History dates of the kings with whom the pyramids are identified.
Or the written record dates are different then the carbon dates as the written dates indicates a date of about 2126 BC.
The second attempt to date the structure was taken because the first attempt had results which conflicted with recorded dates and the carbon-14 readings varied unexpectedly.
Under the heading "old kingdom problem" of the same site.
"It may have been premature to dismiss the old wood problem in our 1984 study. Do our radiocarbon dates reflect the Old Kingdom deforestation of Egypt? Did the pyramid builders devour whatever wood they could harvest or scavenge to roast tons of gypsum for mortar, to forge copper chisels, and to bake tens of thousands of loaves to feed the mass of assembled laborers. The giant stone pyramids in the early Old Kingdom may mark a major consumption of Egypt's wood cover, and therein lies the reason for the wide scatter, increased antiquity, and history-unfriendly radiocarbon dating results from the Old Kingdom, especially from the time of Djoser to Menkaure. In other words, it is the old-wood effect that haunts our dates and creates a kind of shadow chronology to the historical dating of the pyramids. It is the shadow cast by a thousand fires burning old wood."I searched several other sites and was able to gather some more information.
Wood in the area was dated at 3000 BC which would make it 500 years old at the time of the Giza construction if all dates are correct.
The site referanced assumed that the smoke from the wood, which would be a varying factor caused great fluctuations in the dates given on both the 1984 and 1995 testings.
It is possible the fluctuations are from a much different source.
If you assume the flood did happen then the carbon-14 concentration would have fluctuated greatly as it is dependent on radiation and carbon-12 concentrations.
How long would it take for the ozone layer to develop and how long would it take for the concentration of carbon-14 to accumulate a datable percentage if there was little or no carbon 14 to start with.
It is curious to me where they got all the 500 year old wood.
Or was the wood recently cut down having grown in he previous 20 years
but date discrepancies are due to carbon-14 concentration changes.
There are also several dates for the flood, as dates have to be taken from early civilizations due to the absence of specific dates from Abraham to the Christ. Even the birth and Death of the Christ is not known without question.
In any case it would be a stretch to say that there is proof that the civilization existed before the flood.
Unless of course the truth is not the intended outcome.
Duane