CHAPTER IV

THE LUCK OF THE AMMONITES

Discoscaphites jerseyensis

The hill town of Gubbio, about a hundred miles north of Rome, might
be described as a municipal fossil. Its streets are so narrow that on many
of them not even the tiniest Fiat has room to maneuver, and its gray stone
piazzas look much as they did in Dante’s era. (In fact, it was a powerful
Gubbian, installed as lord mayor of Florence, who engineered Dante’s
exile, in 1302.) If you visit in winter, as I did, when the tourists are gone,
the hotels shuttered, and the town’s picture-book palace deserted, it
almost seems as if Gubbio has fallen under a spell and is waiting to be
awoken.
Just beyond the edge of town a narrow gorge leads off to the
northeast. The walls of the gorge, which is known as the Gola del
Bottaccione, consist of bands of limestone that run in diagonal stripes.
Long before people settled the region—long before people existed—
Gubbio lay at the bottom of a clear, blue sea. The remains of tiny marine
creatures rained down on the floor of that sea, building up year after year,
century after century, millennium after millennium. In the uplift that
created the Apennine Mountains, the limestone was elevated and tilted at
a forty-five-degree angle. To walk up the gorge today is thus to travel,
layer by layer, through time. In the space of a few hundred yards, you can
cover almost a hundred million years.
The Gola del Bottaccione is now a tourist destination in its own right,
though for a more specialized crowd. It is here that in the late nineteen-
seventies, a geologist named Walter Alvarez, who had come to study the
origins of the Apennines, ended up, more or less by accident, rewriting
the history of life. In the gorge, he discovered the first traces of the giant
asteroid that ended the Cretaceous period and caused what may have
been the worst day ever on planet earth. By the time the dust—in this