Doolin Pier – Geology
Doolin pier is situated close to the geological boundary between the limestones which make up most of the Burren and the sandstones and shales which dominate the south and west of County Clare.
The limestone at Doolin pier is part of the youngest limestone in the Burren known as the Slievenaglasha Formation. It is packed with fossils, the most common of which are crinoids. On a freshly broken rock surface you will see sparkles as the light reflects off the calcite crystals that make up the stalks of these sea creatures. These creatures lived in a shallow sea close to the equator that would have been subject to storms and tides which would have broken up and redistributed the remains of the animals once they had died. As these fossils accumulated on the sea floor and got buried they would have eventually been turned to limestone.
Looking at the dark cliffs to the south it is easy to see that they are made of different rock. They belong to the younger Central Clare Group which is dominated by shales and sandstones. The change from limestone to shale and sandstone is evidence of a major change of environment at this time, around 320 million years ago. Black pieces of shale eroded from these cliffs often contain fossils known as goniatites. Goniatites were a type of free swimming, shelled mollusc. They are now extinct but are related to the chambered Nautilus which lives in the Pacific Ocean.