Tourists flock to Italy to see Michelangelo’s David and other iconic hunks of Renaissance stone, but in a trip over spring break, a group of Columbia students got to visit rocks that have shaped the world in even more profound ways. In the limestone outcrops of Italy’s Apennine Mountains, geologist Walter Alvarez collected some of the earliest evidence that a massive fireball falling from space some 66 million years ago was responsible for killing off the dinosaurs. Geologists have trekked to the region since then to study that catastrophic event as well as others imprinted in these rocks.
In March, it was the Columbia students’ turn. Led by Steven Goldstein and Sidney Hemming, scientists at Columbia’s Lamont-Doherty Earth Observatory, and visiting scientist David Barbeau, the students touched evidence of undersea mudslides, the drying of the Mediterranean Sea, and several extinction crises, including the one that ended the Age of Dinosaurs.
From about 200 million years ago to 6 million years ago, the vast, shallow Tethys Sea covered much of the Apennines, in Italy’s Umbria-Marche region. As the tiny plants and animals that lived in the sea died, their shells and skeletons piled up, leaving a record of the environment in which they lived. Later, tectonic forces rearranged this landscape, forming the Apennines in several bouts of squeezing and stretching. The activity left limestones made up of tiny microfossils exposed on land, providing a page-by-page story of the past. [...]