DJC, is this of interest ?
It sounds significant, but I'm not qualified enough to say.
http://www.smh.com.au/federal-politics/political-news/aboriginal-archaeological-discovery-in-kakadu-rewrites-the-history-of-australia-20170719-gxe3qy.html
Certainly interesting, as in most cases the more they did the more you hope to find & tells a bigger story of the past, thanks for sharing
Significant, but inevitable as dating techniques improve and more occupation sites are investigated.
There is a probable occupation site (a shell midden) at Warrnambool that has a 60,000 date. Many archaeologists doubted that the shellfish were the remains of human meals because it was older than sites in northern Australia. Now it fits the likely colonisation model.
DNA evidence suggests that the ancestral Aboriginal people left Africa around 70,000 years and 5,000 years to get from Africa to Australia seems reasonable.
We have a pretty impressive cultural history in this country. In time it will be embraced by most Aussies :)
Significant, but inevitable as dating techniques improve and more occupation sites are investigated.
There is a probable occupation site (a shell midden) at Warrnambool that has a 60,000 date. Many archaeologists doubted that the shellfish were the remains of human meals because it was older than sites in northern Australia. Now it fits the likely colonisation model.
DNA evidence suggests that the ancestral Aboriginal people left Africa around 70,000 years and 5,000 years to get from Africa to Australia seems reasonable.
We have a pretty impressive cultural history in this country. In time it will be embraced by most Aussies :)
Hear, hear! :)
CL dating, wonder what the two sigma error bars are....
Optically Stimulated Luminescence (OSL) dating determines when grains of sand were last exposed to sunlight. Radiocarbon dating requires organic material (that often doesn't survive) and is not very reliable once you get past 45,000 years.
I'm not really familiar with the technology but I know that often only a couple of grains of sand in a 100gm sample will give reliable results.
Any scientist worth their salt publishes the uncertainty estimates, it's a key part of geochronolgy, or other quantitative technique for that matter.
C14 dating is unreliable post about 45 k due to the half lives of the radiogenic system. After that time the there isn't enough to measure... Analytical uncertainty exceeds instrumental precision.
Any scientist worth their salt publishes the uncertainty estimates, it's a key part of geochronolgy, or other quantitative technique for that matter.
C14 dating is unreliable post about 45 k due to the half lives of the radiogenic system. After that time the there isn't enough to measure... Analytical uncertainty exceeds instrumental precision.
yeah, the +/- numbers (error range) is always useful - unless you're a climate scientist!
Any scientist worth their salt publishes the uncertainty estimates, it's a key part of geochronolgy, or other quantitative technique for that matter.
C14 dating is unreliable post about 45 k due to the half lives of the radiogenic system. After that time the there isn't enough to measure... Analytical uncertainty exceeds instrumental precision.
Ive also heard that C14 dating fails to take into account the rate of change of Carbon in the atmosphere, and makes the assumption that it is today what it was when the item is being dated.
I dont know much about this stuff, but I am always fascinated to learn about cultural history.
Ive also heard that C14 dating fails to take into account the rate of change of Carbon in the atmosphere, and makes the assumption that it is today what it was when the item is being dated.
I dont know much about this stuff, but I am always fascinated to learn about cultural history.
Radiocarbon dates are calibrated to take into account fluctuations in atmospheric CO2.
If I remember correctly, there's a 66% probability that the actual age of the object being dated falling within the + or - range.
There are strict conventions about publishing radiocarbon and other radiometric dates.
Correct. Ages are normally quoted at 95% confidence levels (standard deviations) or 2 sigma values.
C14 has been corrected using dendrochronology, ice cores and oxygen isotopes (partitioning of atmospheric gases are temperature dependent). It's a robust technique.
Problem with most chronological work is not the technique, but the sample it is applied to.
The people involved in this work will be giving a paper at the Australian Archaeological Association conference in Melbourne in December. It should be interesting.
I should have mentioned some of the stone tool discoveries.
Edge ground tools or stone axes are generally associated with early agriculture and are usually found in sites less than 10,000 years old. Aboriginal people had stone axes well before that (>20,000) but this site pushes the earliest stone axes much further back.
Other artefacts indicate a seed grinding technology. Once again something that is usually associated with agriculture or in the relatively recent past in Australia.
How do they differentiate on digs if stuff might have been buried deeper by actions unknown to the investigators?
I understand deep digs, but shallow digs like this?
Would sediment moved by flood be optically reset?
How do they differentiate on digs if stuff might have been buried deeper by actions unknown to the investigators?
I understand deep digs, but shallow digs like this?
Would sediment moved by flood be optically reset?
Missed your question LP.
That's a science in itself and it's called taphonomy. One thing that good archaeologists will do is look for conjoins, that is, two or more chips from stone tool manufacture that fit back together. Conjoins lying close together indicate not much post-depositional movement. If they are separated by considerable depth then the deposits are likely to have been disturbed.
All archaeological deposits are disturbed by subsequent human activity, burrowing animals, roots, erosion and many other factors. Understanding that disturbance is the key to good archaeology.
Sand grains are optically reset by exposure to sunlight. If flood waters scoured part of the site away 5,000 years ago, the exposed sand grains would be reset at 5,000 years. Any archaeologist worth her salt would recognise that disturbance.
Missed your question LP.
That's a science in itself and it's called taphonomy. One thing that good archaeologists will do is look for conjoins, that is, two or more chips from stone tool manufacture that fit back together. Conjoins lying close together indicate not much post-depositional movement. If they are separated by considerable depth then the deposits are likely to have been disturbed.
All archaeological deposits are disturbed by subsequent human activity, burrowing animals, roots, erosion and many other factors. Understanding that disturbance is the key to good archaeology.
Sand grains are optically reset by exposure to sunlight. If flood waters scoured part of the site away 5,000 years ago, the exposed sand grains would be reset at 5,000 years. Any archaeologist worth her salt would recognise that disturbance.
Cheers DJC, thanks for the explanation.