Carbon Dating the Great Pyramid - Do you think radiation from the stones is messing with it?

originally posted by: bloodymarvelous

originally posted by: Harte

originally posted by: bloodymarvelous

originally posted by: Harte


The accepted explanation for the dating variance is the use of "old wood." Decent wood was scarce if not absent in Egypt.There's a lot you can get out of a piece of wood before you burn it to make lime or whatever.

Harte

I've read that. But it's pretty thin. That's an awful lot of 374 year old wood.

Not really.
The age difference you're talking about is not indicated by every sample tested, just SOME of the samples tested.


Harte

I don't know where you are getting that from. The articles I'm reading say 374 was the average for the 1984 study.

Then they did another wider study in 1995 using stuff from other monuments and from the work camps near the Giza pyramid, because they wanted to see if their overall dates for the period were off, and that moved the date a bit closer.

archive.archaeology.org...


It's kind of a neat trick. One study takes all of its datable material from the pyramid itself. The other gathers stuff from the nearby work camps. And then we just pretend to ourselves that we are seeing a "disagreement" between the two studies.

No. Both studies took samples from all over Giza, including the GP.

Harte

originally posted by: bloodymarvelous

originally posted by: Harte


The accepted explanation for the dating variance is the use of "old wood." Decent wood was scarce if not absent in Egypt.There's a lot you can get out of a piece of wood before you burn it to make lime or whatever.

Harte

I've read that. But it's pretty thin. That's an awful lot of 374 year old wood.

If all of the samples had been taken from one part of the pyramid, or even near each other, then I'd buy it. Then maybe his samples would all trace back to just one bonfire. But if they're spread out, then that means all or most of the mortar has to be from the same year.

That isn't actually what it means though. At the beginning of your second citation discussing the discrepancies between the 1984 and the 1995 data sets, they are pretty clear that the 374 year discrepancy is based on the mean/average of all of the 14C dates obtained in the '84 study combined. In addition to the 374 years being a mean, they also don't disclose the calculated margin of error. From personal experience, 374 years off from the historical record on a 4500 year old monument... it is for all intents and purposes, a home run.

To illustrate it a little better, the following (also from your citation) shows the different results from a single pyramid, Sahure's from the 5th Dynasty.

Maybe it could have been retasked from a single big construction project that happened around the same year, 374 years prior? Maybe from tearing down a really big palace or a whole city and retasking the support beams? Something pretty big, though.

If they were just gathering old scraps from all over, then the dates would vary wildly.

If you look at the photo above, you'll see that the dates do in fact vary quite dramatically. And that's for one specific structure. When you take material from the multiple sources used for the above studies, you average out both the dates and ascribe a margin of error to them.

Also to add a little to Harte's point regarding recycling of wood because of its scarcity-

The pyramid builders often reused old cultural material, possibly out of expedience or to make a conscious connection between their pharaoh and his predecessors.Beneath the 3rd Dynasty pyramid of pharaoh Djoser, early explorers found more than 40,000 stone vessels. These vessels included inscriptions of most of the kings of the 1st and 2nd Dynasties, but Djoser’s name occurred only once. Did Djoser gather and reuse vases that were already 200 years old from tombs at North Saqqara?

In the 12th Dynasty, Amenemhet I (1991-1962 BC) left clear evidence of this kind of recycling. He took pieces of Old Kingdom tomb chapels and pyramid temples (including those of the Giza Pyramids) and dumped them into the core of his pyramid at Lisht.

You have to read their words really carefully here. They're being very crafty.


The first article is Lehner speaking first hand, about what he himself did in 1984. And it looks like he only took samples directly from pyramids.

www.pbs.org...

[post]Lehner[/post]
So it occurred to me that if we could take these small samples, we could radiocarbon date them, not with conventional radiocarbon dating so much, but recently there's been a development in carbon-14 dating where they use atomic accelerators to count the disintegration rate of the carbon-14 atoms, atom by atom. So you can date extraordinarily small samples. So we set up a program to do that. And it involved us climbing all over the Old Kingdom pyramids, including the ones at Giza, taking as much in the way of organic samples as we could. We weren't damaging the pyramids,

Then here's the article your chart comes from:

www.aeraweb.org...


And what they say about the 1995 expedition:

1994-1995
In 1994-1995 the David H. Koch Foundation supported us for another round of radiocarbon dating.

We broadened our sampling to include material from:

The 1st Dynasty tombs at Saqqara (2920-2770 BC).
The Djoser pyramid (2630-2611 BC).
The Giza Pyramids (2551-2472BC).
A selection of 5th Dynasty pyramids (2465-2323 BC).
A selection of 6th Dynasty pyramids (2323-2150 BC).
A selection of Middle Kingdom pyramids (2040-1640 BC).

We also took samples from our Giza Plateau Mapping Project Lost City excavations (4th Dynasty), where we discovered two largely intact bakeries in 1991. Ancient baking left deposits of ash and charcoal, which are very useful for dating.

The 1995 set of radiocarbon dates tended to be 100 to 200 years older than the Cambridge Ancient History dates, which was about 200 years younger than our 1984 dates.

So now they're mixing in samples from the work camp near Giza, which we already have the diary of Merer to confirm the timeline of.


The actual chart you posted comes from one of the 1995 samples. The pyramid of Sahure

en.wikipedia.org...

Which is ruined today, but shows the same type of construction as Giza. On the upside, that might allow them to get samples from closer to the structure's core.



The other chart they put in that article was also from 1995, and was the pyramid of Senruset

en.wikipedia.org...

Which incorporated a lot of mudbrick, and so I'm not sure it really counts as being part of anyone's very old pyramid list anyway.

originally posted by: Harte

originally posted by: bloodymarvelous

originally posted by: Harte

originally posted by: bloodymarvelous

originally posted by: Harte


The accepted explanation for the dating variance is the use of "old wood." Decent wood was scarce if not absent in Egypt.There's a lot you can get out of a piece of wood before you burn it to make lime or whatever.

Harte

I've read that. But it's pretty thin. That's an awful lot of 374 year old wood.

Not really.
The age difference you're talking about is not indicated by every sample tested, just SOME of the samples tested.


Harte

I don't know where you are getting that from. The articles I'm reading say 374 was the average for the 1984 study.

Then they did another wider study in 1995 using stuff from other monuments and from the work camps near the Giza pyramid, because they wanted to see if their overall dates for the period were off, and that moved the date a bit closer.

archive.archaeology.org...


It's kind of a neat trick. One study takes all of its datable material from the pyramid itself. The other gathers stuff from the nearby work camps. And then we just pretend to ourselves that we are seeing a "disagreement" between the two studies.

No. Both studies took samples from all over Giza, including the GP.

Harte

You're right. I misread what he was saying.

There were more pyramids than Giza in the 1984 study, but it was just pyramids, not surrounding sites.


It's kind of important, though. Because one study is exclusively targeted at the stones under the casing stones, but the other incorporates samples from the nearby work camp.

If you're trying to see whether Khufu built the whole thing, or just the casing stones, or just the casing stones and outer wall, the 1995 study won't help you.

a reply to: bloodymarvelous

No, I get all that. My main point was in how they calculated the ages in radiocarbon years, why one just age was listed and how there is always a margin of error that is pretty well known and calculable. Especially when using scanning electron microscopy which gives a much more accurate date and can stretch the viability of samples back to at least 100Ka befor the samples get to small and its difficult to determine which was original 14C and which 14C was recently converted from N. Unfortunately a lot of stuff geared towards lay people excludes the +/- x-years after the date they ascribe.

I see your point now. Also I have to admit that 70 samples is actually a pretty small data set to draw a statistic from.

I was wondering if more complete information was available and after some searching I was able to find something more complete here:

journals.uair.arizona.edu...


They mix the 1984 and 1995 results together, but there is a part near the end of the paper where they show you just the samples taken from the Khufu pyramid itself.

I'm not sure I'm reading it right, but it looks like the statistical mean was between 4147 and 4157 Before Present? Which I guess makes it about 419 years younger than the accepted dates of 2560-2580 BC? Instead of older?

The mean for the production center nearby was 4090 years BP. So at least those two things are in agreement.


At least the matter is less blurry now.

originally posted by: LABTECH767
a reply to: bloodymarvelous

The problem is that such filling material used on the outside of the pyramid even several courses down could actually date from very much later than the real date of the structures build and of course what does the sphinx stelae actually say
www.ancientegyptonline.co.uk...

So this stelae show's that it was actually seen as a duty or at least a propitious activity of the pharoah - at least from this time onward and indeed perhaps prior to this time to restore, clean and rebuilt this ancient treasure and given the one up man ship of many pharoah's and pharonic dynasty's it is likely there was even attempt to upstage Thutmosis act at the site which of course mean's the entire plateau may have been renovated not once but several time's, even the pyramid's may have been at least partially rebuilt and even perhaps expanded with outer layers added to them or at least replaced during these renovation's.

So bare this in mind.

I don't buy carbon dating. The very first people who came up with it had nothing to go on but their opinions, after that everybody who heard of it thought since a "scientist" talked about it, it was gospel. Nobody knows if something is 1 million or 50 million years old.

originally posted by: korath
I don't buy carbon dating. The very first people who came up with it had nothing to go on but their opinions,

What the hell does this even mean? You make it sound like Chemists don't understand how isotopes and half lives work! While the initial 14c testing wasn't super exacting in its accuracy right out of the gate, Libby and subsequently others, were able to establish margins of error and obtain accurate readings going back to 50-60 Ka before present. Today, using scanning electron ,microscopy we can actually count the exact number of carbon 14 atoms left in a given sample and because of the level of precision, you can get very accurate dates up to 100 KA before present.

after that everybody who heard of it thought since a "scientist" talked about it, it was gospel.

No, the information is readily available for you to read and investigate for yourself. Nobody is asking you to take anybody's word. In fact, engaging in due diligence is actively encouraged. Furthermore, those of us who understand concepts like due diligence actually went to the library and looked up the actual papers and other published work related to the research, primarily that done by Libby in the mid 1940's with the first batch of usable data coming back in 1948... but the point is that just because you can't be bothered to check facts for yourself ( much easier these days too as you can email the authors of papers directly and ask them questions ) doesn't mean that everyone else just shrugs their shoulders and says "Eh... Dr. Smith at Cornell says its true so it must be. End of story."

Nobody knows if something is 1 million or 50 million years old.

Not only are the half lives of isotopes known and easy to calculate, but no single method is typically used to obtain a sample. Cross referencing is the norm. It's also important to note that 14C is easy to calibrate against dendrochronology and Ice Core samples. The dendrochronology is limited in years because trees don't live forever but when the margin of error is calculated in, if the samples are accurate in a 400 year old tree and equally accurate in a 900 year old tree, the burden becomes yours to demonstrate why it is an ineffective dating method at older dates. Ice cores are another great source to calibrate against because in some instances you will get really lucky and have organic matter mixed in with your core sample. The organic matter within your core can be given an estimated age based on its location in the core and can then be sent to another lab to have them independently date the sample using 14C. If both of the dates (location marker date and date in radiocarbon years) agree within the margin of error then it is more than acceptable as a calibration comparison.

I suspect though that despite your reply pertaining to Carbon Dating, that you don't actually understand the topic at all if you are then throwing out dates between 1 and 50 million years in age. "Carbon Dating" is a specific radiometric dating technique that measures the amount of radioactive carbon 14 left within a sample of organic material (Bone, teeth, hair, flesh, wood, plant material and charcoal are some examples) Rocks, permineralized fossil, anything that was never alive... unable to use 14C dating. And as I mention at the beginning of my reply, standard 14c dating can get accurate dates back to about 50 KA before present. 14c assisted by SEM can get you to ~100KA +/- but gets you a very accurate result due to the abil ity to literally count each individual carbon 14 atom.

There are s number of radiometric dating techniques available depending on factors like the material you are attempting to date or the layer of strata it is found in. As I said, there are several different techniques that use various elements as markers or measure the ratios remaining such as U-238/Pb which is used primarily on Zircon and can date in the range of 2.5 million to 2.5 billion years. There is K/Ar dating using the rate of decay from Potassium-40 to Argon 40. With a bhalf life of 1.3 Bn this is used to date the oldest rocks on earth. Uranium Thorium dating is good for several hundred thousand years.

Fission Track method
Chlorinee-36 method
Thermoluminescence/Luminescence Dating

That's off the top of my head. Since you didn't put much thought into why you don't buy carbon dating demonstrated by referencing dated timelines from 1 to 50 million years, well beyond the scope of 14C dating then I'm not going to stress too much over adding citations. If you're actually curious and want to understand the science then the old copy and paste into google is pretty easy peazy