How can a seashell end up in rock high on a mountain?

Picture a seashell resting in your hand, cool and bumpy, just like the ones you find on a sandy beach. Now picture a tall mountain, far away from any ocean. Up there, people find shells just like yours, stuck right inside the hard rock!

So how can a seashell end up in rock high on a mountain? Let's follow one little shell on its long, long journey and find out.

Ages ago, a small sea animal lived inside that shell on the seabed, which means the ground at the bottom of the sea. When the animal died, its empty shell stayed right there, resting on the seabed.

Rivers carried mud and sand into the sea, and the mud and sand drifted down and covered the shell. Year after year, more mud piled on top, layer over layer, like blankets on a bed. Tucked deep underneath, the shell stayed safe from the waves.

All those heavy layers pressed down on the bottom ones. Over thousands and thousands of years, the squeezed mud and sand stuck together and turned into hard rock. Now the shell sat locked inside that rock, still under the sea.

Inside the rock, the shell kept its shape and became a fossil, which means a long-ago living thing, or its shape, kept inside rock. The fossil waited there, deep beneath the seabed, while the sea rolled above it. But mountains stand high up on dry land. What do you think could lift that rock all the way up there?

The ground itself does the lifting! The rocky outside of our Earth works like a giant puzzle with huge pieces, and those pieces move about as fast as your fingernails grow. Where two pieces push against each other, they squeeze the rock caught between them.

Squeezed from both sides, the old seabed rock bends, folds and rises out of the water, like a rug you push against a wall. Over millions of years, it climbs higher and higher until it becomes a tall mountain. And the fossil shell rides all the way up inside it.

Seabed, fossil. A seashell ends up high on a mountain because mud on the seabed buried it and hardened into rock, and then the pushing pieces of the Earth lifted that rock, with its fossil inside, up into a mountain.

Next time you look up at a mountain, you can wonder what tiny sea treasures are sleeping inside its rocks.