Vitrification: (Ancient Examples of..)
Excerpt - Vitrified ruins have been found Scotland, England, Ireland, France, Turkey, Iran, Germany and elsewhere, however, out of some 100 forts identified throughout the world, more than half are located in Scotland.
Personally find this stuff to be very interesting. My Scottish Clan is one of the Ancient Scottish Clans so it kinda hits home.
I remember first hearing about this a long time ago and the examples given then were pretty much all in the British Isles (thank you for the link, btw). Still, Schoch was talking about glaciers disappearing so rapidly that earthquakes may have occurred - if something happened it must have been over a very wide area.