Nicolas Steno

Ken Samuelsen/Stockbyte/Getty Images
Ken Samuelsen/Stockbyte/Getty Images

How do geologists sort through the tangle of rock that Earth has moved around, washed away and re-formed for literally millions of years?

Danish thinker Niels Stensen – Nicolas Steno, as he’s known to the English-speaking part of the world – figured out how to do that almost 3-1/2 centuries ago. Scientists are still using his principles today.

It all started with a great white shark.

Suddenly . . . Fossils!

In October 1666, two fishermen from Livorno in Tuscany, Italy, presented the local duke with an awesomely huge shark they had just caught.  The duke ordered its head sent to a local teaching physician – Nicolas Steno, whose ground-breaking research into muscle anatomy had impressed the duke enough for him to give Steno his current prestigious position.

University of California Museum of Paleontology.
University of California Museum of Paleontology.

Steno recorded the shark’s details for history but also noticed that its teeth were identical to a certain type of stone that natural historians had puzzled over for quite some time.

Thinking outside the box, Steno decided that those stones looked like shark teeth because they were shark teeth.  Their unlucky owners had died, the bodies decaying and falling onto the sea floor and getting buried in mud, which then became stone.


At the time, “fossil” meant anything dug up out of the Earth.  Naturally, when our scientist next began to think of other ways a solid object could end up inside another solid object, he didn’t limit his studies to old bones.

Three years later, Steno published a book on how that could happen to bones, minerals, crystals, and even whole layers of rock.  In it, he set out three fundamental laws:

  1. Sediment is deposited in water mostly horizontally because of gravitational settling.
  2. In undisturbed layers of sediment (strata), the oldest will be on the bottom and the youngest on top.
  3. A layer of sediment will stretch out horizontally until it thins away to nothing at the edge of the basin where it was deposited.

Well, duh, right?

It’s actually pretty useful when you’re trying to understand what happened here:

"Taconic Melange" is not the name of a rock band or fancy desert .
Taconic Melange is not the name of a rock band or fancy desert .


For over three centuries, people have used Steno’s principles as a starting point to unravel parts of Earth’s jumbled surface and to uncover long-hidden clues about its past.

Using fossils (modern meaning) found in various identified rock strata, early geologists got an idea of the Earth’s real age, and the intellectual Western world view shifted dramatically.

Steno’s Laws were among the tools used by geologists John M. Bird and John F. Dewey as they studied the Taconic Melange and helped to develop the modern theory of plate tectonics – another huge change in our models of the world.

Geology’s Patron Saint?

It was a big ball that 17th century catch of a great white shark started rolling.

Nicolas Steno also published a book on crystal structure, which gave us Steno’s Law (yes, this man has both a set of scientific laws and another, separate law named after him) and influenced fundamental 19th century work on crystallography.

Later, he became a Catholic priest, got involved in the Counter-Reformation, and eventually did some more anatomical work on the brain and nervous system before he died at the age of 48.  He is now well on his way to becoming a Catholic saint.

And he even has his own Google Doodle.

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