We are here at Seaham exploring the geological history of Durham’s coast.
The three themes we are exploring are:
- The geological setting: Tropical seas and ice ages (The Permian and Quaternary periods)
- The story of the last ice age
- Post Glacial sea-level rise and coastal evolution (hard rock coasts)
We start here by delving into the story of the last ice age.
As we examine the cliffs, we’ll see evidence for interaction between the bedrock (Permian Magnesian Limestone) and the glacial sediments deposited above by an ice sheet.
Above the limestone, we find a dark brown layer that makes up the upper half of the cliff. This layer is composed of glacial sediments that were deposited by the ice during the ice age.
Our main focus here is how the ice and limestone interacted. If we observe the interface between the limestone and the glacial sediment, we can see evidence of the ice eroding and scouring the limestone.
The ice picks up and crushes the limestone, carrying it southwards. During this process, the limestone mixes with other rocks transported by the ice from distant locations. The crushed limestone, together with these stones, forms what we call “boulder clay” or, in modern terms, “glacial till.”
Most of dark brown sediment deposited on top of the limestone, is glacial till.
