[sawsalimb]

A meteor impact,or multiple impacts,makes sense to me as a trigger for climate change,and social upheaval as a result. I can't remember where I read this,but if memory serves,the string of revolutions in Europe in the 1840's were,to an extent,aggravated(or maybe even precipitated)by a volcanic eruption in the Pacific. The eruption threw enough dust into the atmosphere to affect the length of the growing season,and the crops suffered. As the story goes,the shortened growing season led to food shortages,and the food shortages led to civil unrest.

Here's some wild conjecture on my part: another poster on this thread mentioned high salinity levels in the soil,due to over irrigating. Another thought comes to mind,though-what if at least some of the high salinity levels in the topsoil were caused by large amounts of seawater falling back to the surface?(I'm playing the,"Let's Just Say" game,here,so please bear with me). What if the Iraq crater was formed at a time when the area was a shallow saltwater sea? A lot of saltwater would have been thrown up by a meteor impact,and fallen again-maybe enough to affect the salinity levels in the soil for a pretty fair sized area?

[blam]

"As the story goes,the shortened growing season led to food shortages,and the food shortages led to civil unrest."

A number of people subscribe to this theory especially as it relates to the Chinese dynasties.

"A lot of saltwater would have been thrown up by a meteor impact,and fallen again-maybe enough to affect the salinity levels in the soil for a pretty fair sized area?"

A possibility, However, I believe it would have run off and would have been cleansed by the next rain. Something to think about: During the ice age when the oceans were 300-500 feet lower than they are now, the river valleys would have been much deeper, something akin to the Grand Canyon. All the land that is now Basra(Iraq) and Alexanderia(Egypt) was only deposited there within the last 10-12,000 years.