On January 11, 2012, Google celebrated the 374th birthday of geology pioneer, Nicolaus Steno, with a special Google Doodle.
Steno was a 17th-century anatomist and pioneering geologist. After dissecting a shark head, he realized that “tongue stones” — believed to belong to snakes turned to stone — were actually shark teeth.
In Steno’s era, many people believed fossils were just weird objects created by rocks. But he realized that fossils were the remains of ancient organisms.
Besides studying fossils, Steno examined rocks around Tuscany. He found that they were deposited in layers, with older rocks underlying newer rock layers. This basic principle of geology helped later scientists piece together the history of life on Earth.
You can learn more about Steno’s life and work in this Earth Observatory feature story published in 2004.