In honor of the 374th birthday of Danish scientist Nicolas Steno, Google has posted a Doodle in the form of a green-topped rock strata with embedded fossils. The Doodle, which replaces the search engine’s official logo on its home page, reflects the two ideas for which Steno is best know, as one of the founders of stratigraphy and geology.

The Doodle’s strada reflects Steno’s principle of original horizonality, which states that rock layers form horizontally. They only appear differently if later disturbances cause the deviation. Steno’s law of superposition is represent fossils in the lower stratified rock. The law also says that the oldest rock lawyers are deposited on the bottom, unless otherwise disturbed.

Steno, who was born in Copenhagen, left the city in his early 20s for the University of Leiden in the Netherlands, to study medicine. He later studied anatomy in Italy, where his research on shark teeth led him to question how one solid object could be found in another, such as with fossils. Steno published his ideas about solid bodies within bodies in 1669, in his seminal Prodromus dissertation.

Soon after, Steno left science behind, as he converted from his Lutheran faith to Catholicism. He was ordained as a priest in 1675, and two years later became a titular bishop. He died in 1686, at the age of 48, in Schwerin, Germany.

Written by: Karen Benardello