Sillerslev

Introduction

Near Sillerslev, on the island of Mors in northern Denmark, you can find many stones along the beach. Among these stones you can find sea urchins. Look carefully, because these sea urchins are made of stone too. Flint, to be precise. They lived about 66 million years ago in a warm chalk sea, at the end of the Cretaceous and the start of the Tertiary. Much later, during the ice ages, the ice churned up the chalk and flint layers and moved the stones around.

How do you recognize a sea urchin? Just look at the photos. Do you see the dots and the leather-like pattern on the stone? This is what you should look for. You'll often find pieces of a sea urchin and, if you're lucky, one that's still completely whole. Search mainly higher up the beach, where the sand has just been washed away by the sea. The sea urchins are not hidden in the sea, but under the sand.

Geological period