Way back in 2010, I got to go to a seminar given by Walter Álvarez in Coldigioco, Italy.  In 1981, Walter had discovered evidence that led to an explanation for the extinction of non-avian dinosaurs 65 million years ago.  He found in the mountains just outside of Gubbio Italy a thin line of iridium, which is common in asteroids but uncommon on earth.  As it turned out, a huge crater just off the coast of the Yucatan was later discovered.  The Chicxulub Crater showed that an asteroid about 6 miles wide had hit the earth, causing first a firestorm – and also sending lots of debris up into the atmosphere,  which caused a prolonged winter.  This one / two punch did the dinosaurs in – not all a bad thing, since it gave mammals a chance to flourish and evolve into us.  Below that line of iridium, the layer of rock shows lots of evidence of life forms.  Just above it, it was mostly mud.  It wasn’t just the dinosaurs that died off from the global disaster.

Anyway, after we went to the site outside of Gubbio, we had a few hours to walk around the town.  I was completely taken by the architecture – and especially all the neat doors.  It’s not original – I’m sure you’ve seen lots of other such collages, but ever since, I wanted to put together a poster with pictures from Gubbio.  So here is my effort.  It’s a big file, so it may take a while to download.  Gubbio is worth the wait; my poster may or may not be.