November 18, 2015

Some papers. . . . .

Filed under: Dating, Online publications — acagle @ 7:54 pm

For a small project I’m starting on:

Dealing with Outliers and Offsets in Radiocarbon Dating

CALIBRATION EXAMPLES USING OXCAL BAYESIAN TOOLS

RECENT AND PLANNED DEVELOPMENTS OF THE PROGRAM OXCAL

The Groningen Radiocarbon Series from Tel Rehov

Will get back to you once it’s done.

December 4, 2013

Mostly for the nerds

Filed under: Dating — acagle @ 7:26 pm

New radiocarbon dating calibration curve developed

Research led by Professors Paul Blackwell and Caitlin Buck from the University of Sheffield’s School of Mathematics and Statistics and Professor Paula Reimer from Queen’s University Belfast has resulted in a new, internationally agreed radiocarbon calibration curve which will provide improved accuracy to archaeologists, environmental scientists and climate researchers who rely on radiocarbon dating to put their findings onto a reliable time-scale.

The release of the new curve will mean that more precise date estimates can be obtained than previously possible and will reduce uncertainty about the timing of major events in the history and development of humans, plants and animals and the environments in which they lived.

This is actually pretty big news.

November 19, 2013

Sssssome disssssagreementsssssssss

Filed under: Dating — acagle @ 7:41 pm

Scientists disagree on age of Serpent Mound

Serpent Mound arguably is the most recognizable icon of ancient America. Therefore, you might be surprised to learn that much about this mound is arguable, including its age.

Serpent Mound was long thought to be an Adena mound, dating to between 800 B.C. and A.D. 100, but opinions shifted in the 1990s when a team of archaeologists obtained radiocarbon dates on charcoal recovered from the mound.

The results seemed to indicate that the Great Serpent was built by the Fort Ancient culture around A.D. 1120. But a study presented at last month’s Midwest Archaeological Conference in Columbus suggests it might be an Adena mound after all.

As usual from Bradley, neatly laying out the problem, which is a common one.

March 27, 2013

Did I know about this?

Filed under: Dating — acagle @ 3:50 pm

Fish-based diets can cause headaches for archaeologists

To get a radiocarbon date, one measures the amount of remaining Carbon-14 atoms in a sample. The less Carbon-14 left, the older the sample.

“Hard water contains less Carbon-14 than the atmosphere, because dissolved carbonates are Carbon-14 free. A fish caught in hard water has thus a higher Carbon-14 age than contemporaneous terrestrial samples. If such a fish is then cooked in a ceramic pot, the radiocarbon age of the food crust will be higher than if a terrestrial animal was cooked in the pot,” PastHorizonsPR.com said.

It said this is called the “reservoir effect” because “the fish’s carbon actually comes from another ‘reservoir’ than the carbon in terrestrial animals from the surrounding area.”

Hmmmmmm. My first thought was to wonder how this might affect dates on people who consumed the fish as well. There’s a mini-lecture on C14 reservoir effects at the link as well.

October 20, 2012

Muddy lake bed holds radiocarbon ‘Rosetta stone’

Filed under: Dating — Andie @ 1:06 am
Prehistoric layer cake <i>(Image: Gordon Schlolaut)</i>

Prehistoric layers

The latest issue of New Scientist has an article summarizing findings from a paper in the journal Science, discussing how lake sediments in Japan may provide a new way of calibrating C14 dates.

It is hoped that the sediments  will provide accurate calibration  back to 60,000 years ago (current calibration techniques only extend back c. 12,500 years).

The article also has, in typical New Scientist fashion, a helpful couple of lines explaining what radiocarbon dating is all about.

There’s also a longer summary of the paper on the EurekAlert website and another version on the Nature website.

Journal reference: Science, DOI: 10.1126/science.1226660

July 23, 2012

Billed as “more rare than gold” — archaeologist finds important De Soto site literally in his yard

Filed under: Dating, Historic — ArchaeoFriend @ 12:47 pm

White at Potano site 

Archaeologist Ashley White has found artifacts on his property in Marion County, Florida, that strongly indicate that he has found the site of Potano, visited by De Soto in 1539.  Temporal and cultural identification of the artifacts comes from the minting date of a Spanish coin found at the site, and the technological attributes of the chain mail (manufactured by methods that went out of favor by the 1600s).  They also found a domesticated (European-introduced) pig jaw at the site, and glass beads found there are consistent with the date and cultural affiliation.   I love it when dating can be done without expenive radiometric procedures, and I also love it when zooarchaeology can come to the rescue.  Personally, I have been fascinated with the De Soto’s travels in what is now the U.S. for several years (especially the descriptions of the Yazoo area), and the more I learn about DeSoto, the weirder his life story seems to be.  It wasn’t until 1997 that I learned he died in Arkansas and it wasn’t until 2003 (I’m just slow) that I realized that he also traveled to South America and was one of the first Europeans to interact with the Inca (whether you consider that to mean “Inca people,” “Inca empire,” or “Inca/King” — it works for any of the meanings of that word). 

I am totally convinced by the evidence that this is a De Soto site, and here’s the clincher:  Jerald Milanich is quoted saying:

There is absolutely no doubt that is a De Soto contact site, and I am 99.99 percent sure this is the town of Potano

For more links (text and some maps & photos):

http://www.gainesville.com/assets/HTML/DeSotoSitemap/DeSotoSiteMap.htmlhttp://www.ocala.com/section/TOPIC0212

http://www.heraldtribune.com/article/20120711/WIRE/307119996/0/API?Title=New-evidence-of-de-Soto-s-path-to-be-on-display-this-fall

http://www.gainesville.com/assets/HTML/DeSotoTravelsInFlorida/DeSotoTravelsInFlorida.html

July 20, 2012

And here’s what I look like today

Filed under: Academia, Dating — ArchaeoFriend @ 5:14 pm

dog chasing its tail

I am currently waiting for my radiocarbon dating results so that I can make plans on how to date the rest of my sediments. I took a 143-cm long core at an archaeological site. I was hoping to get at least a 3,700 year sediment record, but I am thinking what I got was only recent/historic sediments. There are ways of checking, and I am thinking of using 137Cs (which is an unstable isotope of Cesium with a short half-life of only about 30 years ) or using 210Pb (which is also short lived, in the archaeological sense, with a half life of 22.3 years) to get chronological control on my relatively young sequence. As they say, archaeologists will do almost anything for a date (but we hate waiting or getting bad results) …

June 19, 2012

Speaking of which. . . . .

Filed under: Dating — acagle @ 6:45 pm

Spanish Cave Paintings’ Age Questioned by Archaeologist

Cave paintings in Spain need to be analyzed further before the works can be confirmed as the oldest known examples in the world, an archaeologist said, casting doubt over a paper published in the journal Science.

A team led by Alistair Pike of the University of Bristol in England said in the paper that paintings at El Castillo cave date back at least 40,800 years. That would make them about 4,000 years older than those at the Chauvet cave in France, meaning the Spanish works could be the only cave art ever found to have been painted by Neanderthals, according to Pike.

This site was mentioned in the link below.

May 6, 2012

“I got less and less interested in archaeology because it was so subjective and woolly.”

Filed under: Dating — acagle @ 10:32 am

Archaeology: Date with history

Most of the thousands of carbon dates from archaeological sites from the Middle-to-Upper Palaeolithic era are wrong, say scientists, perhaps even as many as 90%. As a result, archaeologists can agree on the history of this era only in the broadest of brushstrokes.

Tom found himself drawn to the quantitative side of archaeology to help fill in those details. His father had counselled that if he wanted a future in the field, Tom ought to join the push to make it a more rigorous science, emphasizing testable theory, experiment and statistics. So, at his father’s urging, Tom applied for and completed a PhD at the University of Waikato’s Radiocarbon Dating Laboratory in Hamilton, then did a postdoc there. And when a faculty position became available at a better-funded lab at the University of Oxford in 2000, he moved back to his birth country.

Any idea that archaeology hasn’t gone in the direction that Charles predicted is dispelled by a visit to his son’s workplace. Its centrepiece is a giant £2.5-million (US$4-million) particle accelerator, which is used to tot up the number of radioactive carbon molecules in a sample.

Good article (doesn’t he look like Bob Geldof in that photo?) Nature also has a special Peopling the Planet issue, though I don’t know how much is open to the public online.

September 27, 2011

I have done it

Filed under: Dating, Historic — acagle @ 6:57 pm

Dated my first historic artifact, that is. Well, maybe not the first, I’m fairly certain that I’ve done something similar with some odd objects or other in the past, but this one was actually recovered on an archaeological project — monitoring anyway — and, without the date actually being stamped on the thing, I have assigned a secure date for its manufacture. To wit:
Desert Fox

It’s got a makers mark of an overlaid diamond and ‘O’ (see here) with a 20 to the left and a 2 to the right. It’s also got “Duraglas” stamped into the side. I found that this was an Owens-Illinois Glass Co. bottle and their Duraglass product was not produced until 1940. The 20 represents its Oakland CA plant — 20 had been used until 1940 for it Backinridge, PA plant also — and the ‘2′ represents 1942. . . .hmmmm. Something doesn’t make sense. Before 1940, the date digit was supposed to represent the last digit of the year — 0 for 1931, 1 for 1931, etc. — but after 1940 they either added a period to indicate 1940+ or two digits — 4. or 44 = 1944 — but this has no period, but if Duraglas wasn’t used until 1940. . . . .a quandary. Maybe I’m not as certain as I thought. Well, needs more study, I think. Seems to be a beer bottle as well, since I have read that the stipling it has was used in conjunction with the script ‘Duraglas’ for beer bottles. Well, at any rate, I was quite thrilled at at least begin to pin a date on something. Hopefully, I can resolve the discrepancies at some point.

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