Impact events in holocene times?

[David B]

I watched a programme on the History Channel on tv the other night, which suggested that an ocean impact around 2800 BC had impacted the Indian ocean, causing chevron patterns of dunes in Madagascar which are hard to explain otherwise, and which would have had a large impact on coastal human settlement, particularly around the Indian Ocean.

http://www.cprm.gov.br/33IGC/1338188.html

If this happened, it might also be a potent source of flood legends.

Furthermore, it's suggested that an impact event in the Gulf of Carpenteria around 535 AD also cause chevron dunes, and there is a well known tree ring anomaly around that time, with an an impact on the Dark Ages. This has also been attributed to an explosion at Krakatoa, but this seems in doubt.

And then again there is the putative Younger Dryas event, though this again is somewhat controversial.

http://en.wikipedia.org/wiki/Younger_Dryas_impact_event

Do people think that impacts and airbursts have been underrated as influences on human history?

David

[Lisa0315]

Interesting, David.

I am not a very science-y person so I will not speculate, but I will definitely be following along as a lurker.

Lisa

[Berthold]

Another Alexander Tollmann (http://en.wikipedia.org/wiki/Tollmann's_hypothetical_bolide)? ;)

[David B]

Another Alexander Tollmann (http://en.wikipedia.org/wiki/Tollmann's_hypothetical_bolide)? ;)

Sorting out the good stuff from the crankery is not easy, I think.

Even the cranks might have something of value in what they say. Even Velikovsky. When I read one of his books as a teenager, it was immediately apparent to a student of A level physics that a lot of what he said was just so much tosh, yet his collection of historical references which are consistent with impacts and airbursts, as far as I recall, was impressive.

I've always had a layperson's interest in earth sciences, including vulcanism, earthquakes and extraterrestrial events impacting on earth, and it is becoming increasingly apparent from what I've been seeking out that airbusts and impacts are much more common than was thought a few decades ago.

David

[RAFH]

This has been discussed previously elsewhere. My comment then, as now, is what's happened to this investigation. They speculated on this in 2004, visited the supposed chevrons in 2006 and then ... ... ? The were supposed to get dating on the materials they collected, did the program indicate this had been done?

My skepticism is based mostly on their weak evidence, you can find craters or crater-like formations in a general given direction from nearly anywhere. I looked at the chevron formations on Madgascar, funny thing, they start at the south point of the island and continue up the western shoreline, the side opposite the identified crater, yet there are none along the eastern shoreline. Perhaps that's a matter of topography, but it doesn't seem to vary that much, more like it's wind patterns. I've also seen this same chevron pattern in lots of other places, yet no claims of crater related tsunamis.

Not saying it's not a valid concept, just the evidence is spindly and hasn't been forth coming. It's been some three years since they collected the samples, surely they've had time to date the materials and put this into the mill for review, rather than run it through the media first. It just seems there is was real urgency to get this out there for consumption rather than going through the usual channels.