Scientists think they can now tie the disruption that hit Maya civilisation in the 6th Century to an eruption of the El Chichon volcano. A Dutch team has investigated ash fall deposits, finding the age of the materials to be a good match for the so-called Maya "hiatus". This was a time when the sophisticated central Americans experienced cultural upheaval and political instability. They also abandoned many of their favoured lowland sites. A sulphur spike in ice core records from the poles indicates there was a big eruption somewhere on Earth in AD 540 - right at the start of the multi-decade hiatus.