>GM>However, there is one thing that Jinmium explains that without it is left
>>unexplained. The aborigines used fire to kill game. About 140,000 years
>>ago oceanic cores and lake cores in and around Australia suddenly started
>>showing lots of soot whereas for the 6-700,000 years prior to that, there
>>was no soot at all. The argument from these cores has been made that this
>>represents the time that humans first occupied Australia. If the Jinmium
>>dates hold up, then everything fits together. We know that Homo erectus
>>crossed the ocean 700,000 years ago and was on the island of Flores,
>>Indonesia. It isn't far from there to Australia (indeed natural forest
>>fires on Australia could have been seen from Timor an Island not far from
>>Flores.).
>
>Australia is a dry, flat continent. It is often ravaged by
>lightning-lit fires in the outback. El-Nino effects can cause a few
>years of droughts within otherwise wet periods. Widespread fires in
>Australia within an otherwise wet climate could have been a natural
>consequence of the beginning of such similar climate patterns. In
>fact Australia is experiencing such El-Nino conditions right now. I
>saw a fire chief on TV who said the majority of the wildfires in
>were caused naturally by lightning.
>
>OTOH I have no problem with Homo erectus being in Australia 700,000
>years ago.
Nobody said that H. erectus was in Australia 700,000 years ago, least of all I.
The issue was whether the Jinmium art was the product of
>H. erectus or H. sapiens. If it is 176,000 years old, then either:
>a) it was H. erectus (which would make him more intelligent than
>previously thought) or b) it was H. sapiens (which would make him
>older than previously thought). Since there is no other evidence
>elsewhere for either a) or b), and we know about El-Nino caused
>fires in Australia, I prefer the latter explanation.
Why no fires prior to 140,000 years ago. The entire pattern of soot in the
air around Australia, recorded both in the Lake George Core and in oceanic
cores changed significantly from the pattern seen in the earlier rocks.
>
>GM>Anyway, I will await the outcome before removing it...If the dates
>>fail, you can be assured that I will remove it from my list. I
>>have already removed Orce from the copy that went into the book.
>
>OK. But the study casts doubt on *all* the dates obtained by
>thermoluminescence:
>You might consider some such disclaimer in your list?
Stephen, you haven't even looked at the list so you really don't know what
you are talking about here.
I would also like to point out that you ignored the whole reason for the
doubts about Thermoluminescence and the counter comments by those involved
in the Jinmium dates.
Here is afuller account than your mere reporting that there are problems.
Note the Jinmium teams responses to the criticisms.
"While some electrons requre only a few minutes of sunlight to be
bleached, or freed from their traps (the easy-to-bleach signal), others need
hours or even days of ultraviolet light (the hard-to-bleach signal). If
soil was blown into the site by the wind, the minerals probably did see
enough light to be entirely bleached, says Huntley. But sediment deposited
by a river or glacial outflow may not have been thoroughly bleached. As a
result, the luminescence age it yields will be misleadingly old."~Ann
Gibbons, "Doubts Over Spectacular Dates," Science 278(Oct 10, 1997), p.
220-222, p. 221
"'The trouble with the site is the date that was published based on the
assumption that the quartz got fully bleached,' says Feathers, who is
working to correct the problems with the OSL dating, which is better than TL
at measuring the more reliable, easy-to-bleach signal. Hornyak, however, has
said he is 'very confident' of the TL dates because repeated tests on the
sediments have yielded the same result.'"
Rubble Trouble
"A problem of a different sort is undermining the TL dates on sediments
at the Jinmium rock shelter; pebbles of crubly sandstone from the boulder
wall or bedrock jumbled into the dated sediments. Because the rubble might
not have been bleached at the same time as the sediments, it could have
thrown off the dates.'Where there is rubble, there may be trouble,' jokes
Richard 'Bert' roberts, a geochronologist at La Trobe University in
Bundoora, Australia, who has dated many of the earliest sites of human
occupation in Australia.
"Fullagar noted in his paper in Antiquity that although some of the
layers he dated contained rubble, none was found in the layer with the
oldest stone artifacts. Still, says Roberts, undetected grains from the
wall of the rock shelter or from the bedrock below the sediment layer could
have been mixed with theq uartz that was dated. In a sample of 100 grains,
he says, it would take just two 250,000-year-old flecks of quartz to give an
overall date of 6000 years, even if the rest of the sample was just 1000
years old."~Ann Gibbons, "Doubts Over Spectacular Dates," Science 278(Oct
10, 1997),
p. 220-222, p. 221
Now, I don't know how this will turn out. Jinmium may become much younger
or it may be verified. As of this moment the date has not been overturned.
It would be better in the future when you criticise something that you
include as complete an account of the issues and the responses. As it was,
all you did was say there was doubt. There is always doubt.
glenn
Adam, Apes, and Anthropology: Finding the Soul of Fossil Man
and
Foundation, Fall and Flood
http://www.isource.net/~grmorton/dmd.htm