ACS Chemistry for Life

Helen Vaughn Michel (b. 1932) pioneered the use of high-tech chemical instruments for studying archaeological artifacts. With her powerful tools, she pinpointed the geographic origin of the clay in ancient pottery—a clue to who made it and to the history of ancient trade and communication. Michel was also on the research team that uncovered what caused the mass extinction of the dinosaurs 65 million years ago. She detected chemical traces of the massive asteroid collision that sealed the dinosaurs’ fate.

Michel was also involved in one of the biggest science news stories of our time, the hypothesis put forth in 1980 that a giant asteroid hit the earth 65 million years ago, explaining the extinction of the dinosaurs. Scientists hypothesized that the impact of the asteroid sent so much dust and debris from the earth’s surface and the shattered asteroid into the atmosphere that the earth was shrouded in darkness for an extended period. Extreme cold and lack of sunlight killed off almost all vegetation and led ultimately to starvation among all species, including the dinosaurs. The hypothesis was based on the discovery of a 65-million-year-old layer of rock found in Italy. The layer was rich in the element iridium, rare on earth but common in asteroids. If the hypothesis were true, and the dust eventually settled over the earth’s surface, then 65-million-year-old iridium layers would exist around the world, and all they would have the same chemical composition, having come from the same asteroid. Michel was part of the team that helped show that both of these predictions were true.

Visit Chemistry in History to learn more about the work of Helen Vaughn Michel.

Excerpted with permission, Chemical Heritage Foundation
www.chemheritage.org