Shropshire's incredible journey
PUBLISHED: 15:59 03 December 2010 | UPDATED: 15:57 20 February 2013
How did our county become the place it is today? Liz Etheridge of Shropshire Wildlife Trust goes on a voyage of discovery
How did our county become the place it is today? Liz Etheridge of Shropshire Wildlife Trust goes on a voyage of discovery.
If you've ever wondered why Shropshire has such an amazing diversity of landscape and habitats, the answer lies beneath the green mosaic of grassland and coppice, beneath the soil, right down to the old rock bones of this unique county. The land that would eventually become Shropshire has travelled thousands of miles over hundreds of millions of years and experienced extremes of fire and ice, desert and sea; this is Shropshire's incredible journey, told in the landscape around us.
Our story began on a small continent that hovered around the edges of the Antarctic Circle. As they erupted around an already worn-down nub of a mountain chain, volcanoes turned the sky black with their ash, huge bombs of lava and pumice showered down for miles around and thick, treacly lava flows squirted down their flanks. As the millennia passed, miles of lava, ash, mud and sand built up, both on land and in the surrounding sea. Far below, the forces that still drive the dance of the plates across the face of the earth crashed our continent into another, which caused the rocks to bend and buckle, fold and fracture, forced upwards into mountains whose once towering peaks now remain as some of our most iconic hills; the Wrekin as a pile of contorted lava and the Long Mynd as a giant fold of ancient mud.
Life quietly evolved in the seas for billions of years, yet something happened to spur it into new energies. Suddenly, creatures developed hard shells where before were only soft bodies. For the animals, this meant that they could exploit new environments that had previously been too harsh and dangerous, for geologists it meant that animals were much more likely to be preserved as fossils, which added another layer of curiosity and complexity to the story of Shropshire.
The dance continued northwards, new land was created, old land ripped apart by huge faults and an ancient ocean disappeared beneath us, which heralded a continental collision that shaped not only Shropshire, but much of the British Isles. As the ocean closed, shallow seas that had been filled with coral reefs became choked with mud and died. For the first time, all of Shropshire was lifted out of the sea as the ocean finally closed and a giant barren red continent reared up out of the depths to take its place. To see this momentous point in our history, there really is no better place than Ludlow, the white cliffs of Whitcliffe giving way to the Ludlow Bone Bed; marine fossils being replaced by the bones of fish found swimming in fresh water rivers long gone.
Eventually, life scrambled out of the seas and rivers to test this new environment, slowly turning the red land green. As we moved north through the tropics and passed the Equator, thick swamps dominated our landscape built up on the deltas of giant rivers eroding far off mountains and bringing their rich silt to Shropshire. Cycles of flood and mud, trees and seas built up layers of trapped sunlight stored by the giant tree ferns and club mosses as they grew in lush, steaming forests. This 300 million year old energy is what fuelled the Industrial Revolution and still powers much of our modern way of life, as it does at Ironbridge Power Station.
Our eternal dance continued into the arms of another continent, for a time bringing all the land into one place, with Shropshire deep in its embrace. Gone were the swamps, the rivers and the life, replaced by harsh winds drying the soil, blasting the land and driving desert dunes across an empty landscape. The march of the dunes, symbol of a stark, sandblasted landscape has left us with some of our most idyllic countryside like the gentle hills around Bridgnorth where the River Severn has sliced through the crumbly sandstone, exposing the sweeping curves of the fossil dunes.
Nothing stayed the same for long in Shropshire's story, the dry dunes replaced by raging torrents that roared from distant high ground, dumping jumbled masses of pebbles and boulders and carving channels into the sand. At this point, some 250 million years ago, almost all life on earth was wiped out in a series of mass extinctions from which no environment was safe; both land and sea suffered death on an unprecedented scale. But there were survivors. From here on, dinosaurs began their dominance, the giant continent was broken up and Shropshire started the homeward leg of its journey and our tale goes strangely silent.
Meres and Mosses
Much of the reason for this uncharacteristic quiet can be explained by the most recent of geological events to shape our landscape. Our journey takes a pause, brief in terms of geological time but for humankind an eternity. Ice pulsed down from the North and the across from the West, heavy and biting, it ground away at the hills, polishing their rough summits and carving out new valleys. Only the highest peaks stand proud above the white blanket, sharp and shattered by the frosted air. The Stiperstones still stand as witness to this time of ice, their jagged profile and scree-covered flanks a testament to the ferocity of frozen water. Even the hardest rock became powder as the ice sheets advanced and retreated with the seasons and as a warmer time approached and the ice melted away, it left us with a rich layer of rock dust, the watery landscape of the Meres and Mosses and the arterial flow of the River Severn.