Discover how the cliffs along the Seaham coast holds the secrets of ever-changing sea level, an ancient tropical sea and the last ice age.
The Permian Magnesian Limestone: The Permian Magnesian Limestone is a creamy-coloured rock characterized by distinct layers. It dates back approximately 298 to 250 million years ago, originating in a shallow tropical sea known as the Zechstein Sea.
The Zechstein Sea and Cycles of Change: The Zechstein Sea once stretched from County Durham across the North Sea to Central Europe. Over time, the sea filled and drained in a series of cycles, revealing a fascinating story of changing sea levels. At Seaham, we can observe up to three cycles of sea level changes encoded in the limestone layers.
Formations and Evaporites: Seaham showcases the second Zechstein cycle (Z2), which includes the Roker Formation. As the basin filled, thicker limestone layers were deposited, forming the basis of the geological sequence we see today. If you follow the beach from Seaham up to Ryhope you can see the layers of limestone in the cliffs.
When the basin began to evaporate, it left behind thinner layers of evaporites, such as anhydrite and gypsum, although these may be challenging to spot due to dissolution and collapse over time.
