Geological Context II: Neanderthals and the Italian Supervolcano

A week ago I presented an example of the geological context with respect to hominid fossils found in South Africa.   A few days ago I read an article that relates to this previous post and aspects of articles I’ve written the past including the significance of volcanic tephra as markers of historical events (The Toba Super-eruption: A non-flood catastrophe  and Tephra layers as evidence of the passage of time).   The subject of this paper just released by PNAS (Proceedings of the National Academy of Science) is the Campanian Ignimbrite which is a blanket of volcanic ash that resulted from a enormous volcanic eruption of Campi Flegrei in Italy (see map below) which is just to the West of Naples and Mount Vesuvius.  The tephra/ash layer  that resulted from the very large explosion has been dated by conventional radiometric to 40,000 years ago.   How large was this explosion?  It has been estimated that 250 to 300 cubic kilometers of ash and rock was thrown into the atmosphere.  This makes it a bit smaller than other super volcanoes but clearly larger than any in human recorded history.  Compare this to the Mt. St Helens at around 1 cubic kilometer and you can imagine the effects this would have not just on Italy but the entire eastern European and Middle Eastern region.  Because of the unique composition of each volcanic eruption the ash layer from this explosion has now been identified at hundreds of locations from Italy to Russia.   The ability to recognize such unique events in a sedimentary deposit has allowed for very precise synchronization of archaeological and paleoclimatic (ie. ancient climate reconstruction) records.    This ash has been found even in many cave deposit which allow the artifacts in sediments in caves hundreds of miles from one another to be compared with one another.    Typically sediments in caves  (see image of the “hobbit” cave for example) can be dated by several radiometric methods but each of these can have problems with contamination especially with leaching of carbon through layers of sediment.   By identifying ash layers from specific volcanic eruptions more precise dating of sediment layers can be made.    Even if one believes that the radiometric dating of the volcanic ash and thus the date of the eruption was in error, the ash layer itself becomes a nearly indisputable (ie. there is very strong chemical and morphological features of the ash that make it difficult to mistake) marker for that event and thus a common reference point.

Map showing the approximate extent of the Campi Flegrei caldera. Imagine a volcano larger than Vesuvius that has blown it top and then formed a large caldera sunken in the middle. The first and largest event is dated at 40,000 years but additional explosive events happened here several times in the past 10,000 years. Today there are still some sulfur pools and small geysers in the area though the suburbs of Naples have expanded over nearly the entire caldera.  When this volcano blew its top it released an estimated 250 to 300 cubic kilometers of material. Compare that to the 1 cubic kilometer released by Mt St Helens and you can see that this was a very significant event. Image from: http://www.dailymail.co.uk/home/moslive/article-1342820/Vesuviuss-big-daddy-supervolcano-Campi-Flegrei-near-Naples-threatens-Europe.html

How can such “absolute” markers be used to help us understand migration and community development in humans?  Since this ash layer is found over all of Greece, Turkey, Most of Italy and up into Russia any remains of humans or any other organism in a cave or other deposit can be identified as having been deposited either before or after this super-volcanic explosion in Italy.  This is similar to what we saw in the Toba super eruption in Indonesia which spread a thick layer of ash over much of India.  Human artifacts  and fossils have been found well below and up to the ash layer strongly suggesting the presence of humans there prior to the volcanic explosion.   In the case of the Campanian Ignimbrite (CI), which is what the ash from this super-volcano is called, Lowe et al. (2012) found that by comparing many sites with humans remains in southern Europe that this ash layer falls in the period when there are both

Neanderthal and modern humans (referred to usually as anatomically modern humans in these papers) remains.  Further below the ash layer there are only ever found Neanderthal remains and above the ash layer at almost all sites are found only modern human remains.  This transition of Neanderthal populations to modern human populations in European cave deposits has been well known for some time and has been greatly debated.  The questions that have been raised have been about how modern human replaced Neanderthals. Did they push them out, did the hybridize extensively (probably not based on genetic data), did disease kill them, or did the Neanderthals simply die off as the result of multiple causes with no single primary reason.  One popular hypothesis that has been floating around for a while has been that this super-volcano explosion in Italy severely disrupted all populations both directly and by causing dramatic global cooling for years to decades afterward.  This could have pushed the Neanderthals to extinction to be replaced by modern humans who once again migrated back into the area. The ability to identify this particular ash layer now in many locations that have remains of both Neanderthals and modern humans has allowed this question to be more thoroughly addressed.   What they find is that the situation is a bit messier than proposed.  At most sites, there is no evidence that Neanderthals ever came back to the caves after this volcanic cataclysm but there are a few locations where there are some Neanderthal remains in layers just above the ash layer indicating they survived either at that location or migrated back to that location sometime after the event. However, those remains and artifacts are soon replaced in layers above them by modern human remains and artifacts associated with modern humans.   So it could still be that the volcano accelerated the decline of Neanderthals but probably was not the sole cause of their final extinction.

I expect that the ordering of remains from Neanderthals in lowest levels to, at times, mixtures of remains/artifacts to only modern humans on top might come as a surprise to some.  There are thousands of sites with either human remains or artifacts (stone tools usually) that are known across southern Europe and many are found in locations where they are found in layers stacked on top of each other like in caves or flood plain locations along rivers.  But, the exact pattern of Neanderthal and modern human population migrations and changes is not my main interest.   Similar to my last article about hominid remains in caves in South Africa I am more interested in the geological context that this ash layer provides as clear indicator of a past event that we can trace across many locations.

The Young Earth Worldview and the Campanian Ignibrite

As we saw with Doggerland and with the South African caves, the application of the timing of these events severely constrains the timeline of young earth creationists.   Again, we are faced with caves that are clearly of post-flood origin that have sediments that contain human remains.   Standard geological models say that this volcano blew its top 40,000 years ago to produce this ash layer.   That ash layer is found above the vast majority of Neanderthal and some modern human remains and artifacts at hundreds of locations.   Clearly people lived all over southern Europe prior to this volcanic explosion.  Not only that but they had lived there some time as there are remains found in meters worth of sediments in caves that would have had very slow accumulation of material.    Regardless of who Neanderthals were and their relations to other humans, the challenge for the flood geologist attempting to push all evidence of human occupation into a post-flood 4000 year period is to explain how these remains could have been preserved in these locations given these geological constraints.

As I noted in my last article flood geologists feel compelled to explain all human populations as the result of migration of populations from a single location, Babel which is presumed to be in the Middle East.  If this is the case then people didn’t even have a chance to migrate out into Europe until several hundred years after a global flood and that would have been during the time of the flood-induced ice age by creationist reckoning.

Here I need to add one additional piece of data that I have not mentioned yet.  At these sites where the ash is found in deposits, the evidence of the most recent Ice Age is found ABOVE this ash layer.  This can be witnessed in both cores taken from the bottom of the Mediterranean Sea and in these caves.  When pollen and other plant microfossils are examined as well as Oxygen isotopes  there is clear evidence of dramatically cooler environment in the layers above the ash layer especially those dates  20 to 10 thousand years ago.   That evidence consists of things like changes in the plant communities in the area around the caves such that they look more like those of more northerly climates.  The point here is that flood geologist claim there was a single Ice Age after a global flood. The evidence of that Ice Age is seen in these layers of sediments but that evidence strongly suggests that people were present at these locations well before the last Ice Age.  Not only that but populations were widespread and then likely decimated by this cataclysmic volcano.  Such a tremendous event that would have changed the climate of Europe of the Middle East for many years after that would seem to be something that should have been recorded in the history books had it happened only 4000 years ago but there is no written evidence of such an event.

Flood geologist make the frequent claim that the power of volcanoes has declined over time with the largest super volcanic eruptions happening at the end of the flood year or just after the flood.   In “Volcanoes of the Past” John Morris tries to show that the Yellowstone volcanoes where massive compared to today but that today’s volcanoes are smaller.  What he doesn’t mention is the Toba super eruption that blew out more ash than any of the volcanoes that he mentions but as we have seen there are human artifacts found under that ash layer and so the largest super-eruption didn’t occur during or just after the flood as implied.   Here in southern Europe we see another example of caves and sediment layers with evidence of long-term habitation by humans followed by a super-eruption of nearly the size as some of the North American super eruptions.  The Toba eruption was dated to 74,000 years and this one in Italy to 40,000 years.  In both cases young earth creationists have to fit these massive eruptions and all their effects to the climate  and the landscape within a 4000 year period allowing for the migration of humans far and wide prior to those events.

This might seem like rather jarring information to some.  As I said in the last post, I think that the context of human remains and evidence for human occupation in many places in the world is one of the least understood and discussed topics in the conservative evangelicalism.   Typically the portrayal of ancient humans is of populations of many different groups all living simultaneously and being preserved over a short period of time.  It doesn’t take a lot of work to find out that the site where human remains are found in Europe are very complex with human remains and evidences of many different cultures living at one location but over different times found in as much as 50 feet of layers of sediments.  As unambiguous post-flood sediments according to creationists, these record the events of actual people’s lives in the past.  Flood geology attempts to explain most fossils as representing a giant sorting event in a global catastrophe but the same explanations creationists use for the majority of the fossil record cannot be used for these site sites once the context of the site is understood.  Ash layers like the Campanian Ignibrite are one example of a strong marker of a historical event that provides a chronological marker that can be used as a power means of correlating and comparing data sets from many locations.   In the debate over man’s origins many creationists make it sound like these data are easy to understand.  However, I hope that these examples provide a glimpse at the complexity of the human fossil/archaeological record.  This is the type of evidence  that Christians who work in the science are confronted with and try to make sense of.   To interpret this evidence as something other than the origin of all human populations as the result of migration of one family from Noah’s ark 4000 years ago is not just a wacky atheistic theory whose sole purpose is to make humans seems ancient as a plot to discount the Genesis record. Rather , many Christians who have examined the evidence themselves find the young earth ad hoc explanations for these fossils utterly lacking.  How to understand these fossils in their proper Biblical context is not an easy thing but simply pretending that with the right worldview all the data just make sense doesn’t actually make it make sense.

References and further reading:

“Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards”  Lowe et al., PNAS July 23, 2012.

http://www.sciencemag.org/content/315/5809/223.abstract – Science article about the dating of the Campanian Ignibrite