Guest Author - Ann Carroll Burgess
The phrase “historic Britain” generally brings to mind images of pomp and pageantry, crown jewels and architecture of distinction. However, there is an entirely different history of Great Britain which is all too commonly ignored, its natural history. Britain experienced a tumultuous and turbulent natural history of volcanoes spewing towers of lava onto the landscape, mountains being thrust upwards from the earth’s crust and dinosaurs stalking the landscape that would eventually become the moors and lakes of this now geologically quiet country
Great Britain has been carved by glaciers and in some places shaken from the bottom of the sea by the uplift of shifting tectonic plates to form the landscapes with which we are now so familiar.
Not a single patch of land in the British Isles escaped the impact of the Ice Ages. At the height of the Ice Age a sheet of ice more than a mile thick most likely covered the majority of northern England. These glaciers would then erode large areas of the uplands, carving u shaped valleys and other features still visible as hanging valleys and arętes. The passing glaciers would leave behind huge deposits of sand, rubble and gravel over many lowland areas. The melting of these ice monsters would create both the Irish Sea and the English Channel when their melt waters raised the level of the surrounding seas.
Where can you still see evidence of the Ice Ages in Great Britain today?
Cromer Cliffs in Norfolk are one of the best places to see evidence of Glacial till in the British Isles. Till is a mix of silt, clay, sand and gravel, stone and large boulders that have been deposited by passing glaciers. The Cromer Cliffs that run west from the beach area are an excellent location to see this glacial till.
In Wales, Cwm Idwal in Snowdonia is an excellent example of the remains of a cirque or bowl shaped glacier. Cwm is the welsh name for a cirque. These steep walled basins often contain a lake or “tarn. The copious, naturally forming amphitheatres in the hillsides frequently contain plants that are the remnants of the glacial ages, such as the Snowdon lily. The only other places you can find this plant are in the arctic or the Alps.
Those iconic chalk cliffs of Dover are made of billions and billions of fossils of microscopic plankton called coccolithophores whose shells fell like snow to the ocean floor, building up layers of chalky ooze during the Late Cretaceous period some 35 million years ago. The area covered by these phenomena is immense, stretching from this Sussex and Kent coasts to the plains of Salisbury and Wiltshire to the west and Norfolk and Yorkshire to the north.
In Ireland, the Giant’s Causeway, a dramatic basalt feature of hexagonal shapes are said to have been the creation of a mythical giant called Finn McCool so that he could challenge a Scottish giant to a test of strength. Even more intriguing is the actual cause of these stone columns. About 60 million years ago, Northern Ireland was sitting atop a volcanic hotspot in the earth’s crust. Lava from this area forced its way to the earth’s surface and cooled very rapidly when coming in contact with ocean water. As the lava cooled and hardened it would shrink and split forming a lattice of cracks that would produce hexagonal shapes.
England’s geologic history is as varied and dramatic as the political and royal intrigues that would follow and define our images of its history.