Shropshire – set in stone

In 2020 I began work on a manuscript for a book on Darwin’s early life in Shropshire and the influences that moulded a great scientific mind. This is an extract from a draft of the chapter exploring the amazing geology of his home county. The chapter has since been updated and will appear in full in ‘Charles Darwin in Shrewsbury – The Making of a Marvellous Mind’ Amberley Publishing, 18th January 2023.

‘Shropshire exhibits a more varied display of geology than any other area of comparable size in Britain, and possibly the world[1]’.

It is the British scientist Arthur Holmes that we have to thank for our understanding of the age of the Earth. Once described as ’the most famous British geologist you have never heard of’[2], it was Holmes who combined an interest in geology with a fascination in the field of radioactivity to reach some remarkable conclusions. Holmes was in his final year of study at Imperial College London in 1910 when he perfected a technique of calculating the age of rocks and minerals using radiometric dating. Three years later in his book The Age of the Earth[3], Holmes dated the age of our home planet at a conservative 1.6 billion years. By 1946, following refinements and improvements to the technique, the consensus amongst the scientific community was a far greater age of 4.5 billion years. Holmes contribution to our understanding of the Earth didn’t end there, he broadened his study of radioactivity to explore the consequences of the heat emitted from the Earth’s core and suggested that radioactive waves were the engine behind the movement of giant, tectonic plates on the Earth’s surface that had, over those billions of years dramatically shaped and reshaped the landscape. Though radiometric dating was over half a century in the future, Darwin’s perspective and astute sense of observation enabled him to see in the landscape anomalies that fed his curiosity and contributed to his great idea, an idea that subsequent decades of scientific progress has been able to validate.

In 1815, William Smith published his Geological Map of England and Wales and Part of Scotland. It was a timely publication as interest in geology was growing not only amongst the scientific community but also the industrialists eager for the raw materials to drive their dark satanic mills. It was the year of Bonaparte’s defeat by the allies at Waterloo and Charles Darwin was six years old. The science of geology grew as Darwin grew and by the time he attended Edinburgh University, many scholars were specialising in the field. Smith’s map is a remarkable achievement for its age but only hints at the complexity of the landscape in Darwin’s home county. Shropshire became a magnet for pioneering, Victorian geologists such as Murchison, Lapworth and Callaway who plundered county place names as they founded systems that have remained in geological text books to this day such as Caradoc, Wenlock and Ludlow. Shropshire continues to provide a teaching ground for new generations of geologists.

As Holmes was able to prove, the slow, inexorable dance of tectonic plates across the surface of our planet has caused the rise and fall of mountain ranges, the formation of oceans and the creation and destruction of whole continents. The landmass of Shropshire or at least parts of it, have been on an incredible journey beginning some 60 degrees south of the equator, gathering evidence of the ages along the way. As a consequence, Shropshire boasts ten of the twelve geological periods in its landscape[4].

As you approach the county from the North, West or East, the largest landmark is the Wrekin Hill. Rising some 407 metres above sea level, it looms up from the flat, North Shropshire Plain. The hill is a popular destination for walkers, offering spectacular views in all directions, and along its ridge is evidence of ancient, Iron Age habitation. A mile to the West lies the village of Rushton and evidence of a far older age. The stone beneath Rushton was formed in the Precambrian Age between 700 and 545 million years ago.

Alongside the Wrekin is its little sister, The Ercall Hill and here, in an abandoned quarry the transition from Precambrian to Cambrian is visible. Fossil evidence shows the phenomenon that became known as the Cambrian Explosion, on a geological scale, a sudden and spectacular increase of life on Earth. One of the largest and more unusual fossils at The Ercall demonstrates the extent to which the Earth’s surface has contorted. High up on a quarry ledge the stone slope is embossed with the ripples of a sandy, sea bed. On his expedition with Adam Sedgwick to the Welsh valley of Cwm Idwal[5] in 1831, Darwin had seen evidence of this contortion, observing marine fossils in rock strata many metres above sea level. As remarkable as these finds were, Cwm Idwal offered another insight that explained the very making of the landscape itself. It was staring the two men in the face but they couldn’t see it then. So fixed were they on finding fossils that as Darwin admitted: ‘neither of us a saw a trace of the wonderful glacial phenomena all around us.’ Ten years later, Darwin returned to Cwm Idwal with a new perspective and a fresh pair of eyes enlightened by his experience on the Beagle. Here were the ‘plainly scored rocks, the perched boulders’ that he and Sedgwick had seen a decade earlier but now in a moment of clarity, he looked again at the bowl of the valley and the story came to life. He imagined it full to the brim with solid, glacial ice which, over millennia carved the landscape beneath its mass. It was suddenly, startlingly obvious to the extent that he wrote ‘a house burnt down by fire did not tell its story more plainly than did this valley’. Land falls and rises and the jostling of tectonic plates push great mountains into the sky but ice and water are accomplished engineers too.

To the south of The Wrekin, Wenlock Edge rolls South West. Another famous landmark, Wenlock Edge has been immortalized in verse by A.E. Houseman[6]  whose words were the  inspiration for music by Ralph Vaughn Williams[7] , the grandnephew of Darwin. A Silurian escarpment, this dramatic, limestone ridge is riven with the fossils of marine creatures that once inhabited coral reefs.

To the West of Wenlock Edge the town of Church Stretton lies in what is known as the Stretton Fault. This is the heart of the South Shropshire Hills, an area rich not only in geology but folklore too. Legend has it that beneath the Shropshire Hills rest the Anglo-Saxon nobleman Wild Edric with his wife, Lady Godda along with his loyal army. Having changed his allegiance to the Norman King, William, the locals laid a curse on Edric that banished him to a realm beneath the hills only to rise up whenever the country is in peril.

More significantly, the land between Wenlock Edge and Church Stretton takes us on a journey through the late Precambrian, Cambrian and Ordovician Periods to the Silurian, some 90 million years or so of Earth’s history in around 13 miles, as the crow flies.

To the North of the Shropshire Hills the land flattens as far as the Cheshire Plains. From Shrewsbury and out towards Market Drayton, Permian and Triassic sandstone can be found. Sandstone outcrops such as Nescliffe, Pimhill and Grinshill, punctuate the flat topography. The village of Clive was built high on the Western slope of Grinshill and here beside the churchyard of All Saints, an ancient road has been carved out of the soft stone. A few miles north of Clive, close to the village of Prees, the Jurassic Period is represented.

Evidence of the Earth’s more recent history can be seen in an area known as the Meres and Mosses, close to the town of Ellesmere in Shropshire’s ‘Lake District’. Here, pools and peat bogs are evidence of the last great Ice Age. The sheer weight of ice left hollows in the soft ground and as the glaciers receded, they deposited melt water and created the jewels of standing water that give the area its distinctive character.

Over time, and during Shropshire’s epic journey rich, mineral deposits have been laid down. The Snailbeach mine is located beneath a ridge of the Shropshire Hills to the West of Church Stretton, called the Stiperstones. The Romans mined lead in this area and production at the mines didn’t peak until 1860[8].

The predominantly rural landscape of modern Shropshire belies its industrious past. The mineral deposits, coalfields and abundant woodlands provided the raw materials for industrial activity for many centuries, albeit on a small scale until a dramatic breakthrough by Abraham Darby in 1709. Darby had relocated to Coalbrookdale from Bristol. Coalbrookdale is situated to the East of The Wrekin in a vale adjacent to a larger gorge created at the end of the last ice age when a large volume of ice-melt forced a new, southerly path for what we now know as the River Severn.

In Shropshire, Darby had all the raw materials he could possibly need for his latest venture and the glacial legacy provided the industrialist with a thoroughfare for boats to exchange goods and raw materials all the way to the Severn Estuary and the wider world beyond. In a second-hand furnace, Darby perfected a means of smelting iron with coke. More robust than charcoal, coke allowed greater quantities of ore to be loaded into the top of the furnace. During his experiments, Darby stuffed the keyhole of his workroom with rags to frustrate prying eyes yet when the method was perfected, he did not apply for patent, perhaps a mark of his Quaker generosity.

As a consequence of Darby’s breakthrough, output increased at a previously unimaginable rate and the Industrial Revolution began. As output grew, so did the skills of the iron casters; pots, rails, ornate fountains and all manner of goods were cast in iron and the material played many of the roles that plastic does today. A new class appeared in British society, the Industrialist. In the generation that followed were the entrepreneurs Boulton and Watt, friends and collaborators of Darwin’s grandfathers, Erasmus Darwin and Josiah Wedgewood. And all of this enterprise was founded on a geological legacy writ large on the landscape of Shropshire and billions of years in the making.

The most remarkable things can be achieved, given time. Dogs and cats, race horses and racing pigeons have all, to a greater or lesser extent been fashioned at our whim since their domestication began around 40,000 years ago. We have adapted them to suit our purposes and tastes through the process of selective breeding. The change is most dramatic in the case of dogs. Compare a chihuahua with a Siberian husky and it’s hard to imagine they have the same ancestor. During the period of research that eventually led to his greatest work, The Origin of Species, Darwin took time to seek out expert breeders hoping to gain a greater understanding of what changes can occur over time.

There are those who would place the age of the Earth at a mere 4,000 years old, according to calculations based on figures extrapolated from biblical text[9]. On the voyage of the Beagle, Darwin observed in nature what he considered to be subtle adaptations in animals but this was change only possible over a course of years measured not in thousands but millions. 4,000 years is simply not enough time for natural laws to produce the startling variety of life on Earth by so many tiny, incremental changes. Darwin’s Theory on the Origin of Species is complete nonsense without the benefit of time. This perceived anomaly perhaps accounts for the disproportionate attacks on Darwin’s theories more than any other scientific figure, by those whose faith is founded on the account of creation found in the book of Genesis. Darwin had chosen to look outside The Book and the evidence of pre-history was right on his doorstep. He was fortunate to have grown up in a county with a geological clock that started ticking long before Man’s arrival. We know that within a few miles of the family home in Shrewsbury lie stones with stories that began over 700 million years ago. In the hills of South Shropshire we can see the fossils of creatures that swam in long lost oceans and nearby, The Wrekin, formed from lava and volcanic ash that tells of more turbulent times.

The world, as many scientists had come to realise, was in a state of constant contortion; rising and falling, shifting and drifting, a world in motion. Time makes all things possible.

Copyright 2021 Jon Fraser King

Photo: The Wrekin from The Ercall – Jon Fraser King

Charles Darwin in Shrewsbury – The Making of a Marvellous Mind will be published by Amberley on the 18th January 2023


[1] Geology of Shropshire, Peter Toghill, Crowood Press

[2] http://libraryblogs.is.ed.ac.uk/blog/2015/09/18/arthur-holmes-the-most-famous-british-geologist-you-have-never-heard-of/

[3] The Age of the Earth, Holmes, Andesite Press

[4] Precambrian, Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Quarternary

[5] Cwm Idwal was designated a National Park in 1954, the first in Wales

[6] A Shropshire Lad 31: On Wenlock Edge the wood’s in trouble

[7] On Wenlock Edge

[8] In the 50 years prior to the First World War, extraction from Snailbeach Mine amounted to; 132,00 tons of lead, 42,000 of barytes, 4,000 tons of zinc and 900 tons of fluorspar.

[9] In 1654 Archbishop Ussher, Primate of All Ireland, had used a study of the Old Testament to calculate that the world was created at nightfall on the 22nd October, 4004 BC. At that moment, Ussher argued, the chain of events described in Genesis began. Six days later, life on Earth in all its complexity existed and on the seventh day, God rested. Variety, Ussher believed, was fixed.The calculation was not widely accepted in ecclesiastical circles but it was a view that was to find popularity in the early part of the 20th century and is a cause of the supposed conflict between science and religion.

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