[needlenose_neely]

The new idea is that these massive cultural disasters were caused by the impact of comets or other types of cosmic debris on the Earth.

If that were the case there would be massive impact craters that are somewhat fresh.

Where are they?

[slowhandluke]

Where are they? [craters]

Tunguska was a 40Megaton blast, and left no crater. Lots of this type of event across a wide area would be devastating, but leave no craters.

[Mike Darancette]

Maybe Southern Iraq.

[Freedom4US]

There are quite a few likely suspects. Arizona Crater is a famous example. Upheaval Dome might be another, in Utah.

[Dick Vomer]

if that were the case there would be massive impact craters that are somewhat fresh. Where are they?

[Renfield]

“Where are they?”

I attended a lecture by a French scientist (whose name, unfortunately, escapes me at the moment) this past summer at the World Congress of Soil Scientists, who, by use of soil micromorphological techniques, identified the site of one of these impacts. It’s right along the seashore on the northern coast of Africa. She found shocked quartz from the impact in an arc ranging from Spain to Iraq. This was the impact, or one of the impacts, responsible for the ~2300BC catastrophe.

There is also a large, geologically recent crater in Iraq. Its discovery generated quite some interest here on FR a couple of years ago.....Blam or SunkenCiv can probably provide you with a link to pics.