On the British Geological Survey’s map, chalk is represented by a swathe of pale, limey inexperienced that begins on the east coast of Yorkshire and curves in a sinuous inexperienced sweep down the east coast, breaking off the place the Wash nibbles inland. Within the south, the chalk centres on Salisbury Plain, radiating out in 4 nice ridges: heading west, the Dorset Downs; heading east, the North Downs, the South Downs and the Chilterns.

Stand on Oxford Road in the course of the West Finish of London and beneath you, beneath the concrete and the London clay and the sands and gravels, is an immense block of white chalk mendacity there within the darkness like some huge subterranean iceberg, in locations 200 metres thick. The Chalk Escarpment, as this block is thought, is the one largest geological characteristic in Britain. The place I grew up, in a suburb of Croydon on the fringe of south London, this chalk rises up from beneath the clays and gravels to type the ridge of hills referred to as the North Downs. These add drama to quiet streets of bungalows and interwar semis: every now and then a spot between the homes exhibits land falling away, sky opening up, the towers and lights of the town seen far within the distance.

The British Geological Survey (BGS) was established (because the Ordnance Geological Survey) in 1835. The world’s first nationwide geological survey, its authentic remit was to survey the nation and produce a collection of geological maps. At the moment, the BGS, which nonetheless produces the “official” map of the UK’s geology, is greatest described as a quasi-governmental organisation break up between analysis, business initiatives and “public good”. Various its work is now accomplished outdoors Britain: on the time of writing, initiatives embrace research of groundwater within the Philippines and volcanic exercise within the Afar area of Ethiopia.

One week in early October, 4 members of the BGS arrange camp in a self-catering cottage close to the city of Tring within the Chiltern Hills, about midway between London and Oxford. They had been on a coaching train as a part of a challenge to provide a brand new geological map of the chalk of southern England. On the day I arrived, the wood desk in the primary room was coated with maps, books, a half-drunk bottle of pink wine and a packet of chocolate digestives. Area chief Andrew Farrant, tall and skinny, with steel-rimmed glasses, was ingesting a cup of tea. He had a form of leather-based holster hooked up to his trousers, from which swung a geological hammer with a surprisingly wicked-looking lengthy, pointed finish.

The Seven Sisters cliffs in East Sussex, England.
The Seven Sisters cliffs in East Sussex, England. {Photograph}: eye35.pix/Alamy

Farrant has been engaged on the chalk-mapping challenge on and off since 1996. “I’d say that not sufficient consideration is paid by the tutorial analysis group to understanding the geology of the UK,” he stated. “If I used to be doing this [mapping project] in east Greenland, then I’d in all probability get funding for it – east Greenland is horny. And folks are inclined to assume that as a result of we’ve got a geological map of the UK, it’s all been accomplished, however really you’ll be able to nonetheless enhance it.”

The geology of the Chilterns, for instance, was final mapped in 1912. Since then, the self-discipline has modified fairly a bit. Geologists now find out about plate tectonics and radiometric relationship. There are laser-based distance measurements for elevation maps and digital terrain fashions and higher-definition Ordnance Survey maps, permitting hitherto unrecognised options to be recorded. All of this may have an effect on the maps which can be produced.

And in relation to the chalk, these new maps matter in a method they didn’t in 1912, as a result of since then, the inhabitants of the south-east has elevated by roughly a 3rd. Specifically, this soar has put strain on the area’s transport programs – usually created by tunnelling although chalk to type such initiatives as HS2, the Gravesend tunnel and Crossrail – and the area’s water assets, a lot of them saved within the chalk aquifer.

Think about stumbling, blindfolded, via an unknown panorama, uneven terrain underfoot, and enormous, exhausting objects rearing out of nowhere. With out respectable mapping, that is primarily the state of affairs for a tunnelling engineer confronted with an immense block of chalk. “Obstructions are a really huge challenge,” Mike Black, Transport for London’s principal geotechnical engineer, recalled in an interview in New Civil Engineering. “We spend an enormous period of time on desk research attempting to work out the place all the things is or the place it is perhaps.”

An sudden flint band or exhausting rock stratum can shatter the protect of a £100m tunnel-boring machine. Hit a fracture or a seam of clay, and your tunnel – stuffed with males and machines – may flood with water. The Channel tunnel, as an illustration, doesn’t go in a straight line from A to B, however follows as a lot as potential a single layer within the chalk that is without doubt one of the most fitted for tunnelling. To plan the route, engineers checked out samples of chalk from boreholes and analysed the microfossils so as to discover the easiest way via. “That saved Eurotunnel in all probability half one million kilos,” Farrant instructed me.

The world’s first true and complete geological map of a rustic – England, Wales and (most of) Scotland – was printed in 1815, by a surveyor named William Smith. In an age of gents geologists, Smith wasn’t wealthy, posh or well-connected – in reality, his social standing barred him from membership of the Geological Society of London – however he was obsessive about rocks, fossils and the concept of mapping the geology of Britain. He spent years travelling across the nation to collect materials, finally bankrupting himself whereas producing the primary copies of his map.

At the moment, one of many authentic copies hangs within the entrance corridor of the Geological Society’s headquarters in Piccadilly. While you pull again the blue velvet curtain defending it from the sunshine, one among first issues that strikes you is its magnificence. The UK is furrowed by a collection of curving strains working downwards proper to left to succeed in a degree round Taunton in Somerset. The nation is a marbled mass of forest inexperienced, caramel brown, bubblegum pink, wealthy purple and pale lavender.

Smith’s map, you’ll be able to inform at a look that the nation is older within the west and youthful within the east; that, roughly talking, should you start within the south-east and journey north-west as much as the Highlands of Scotland, you journey again in time – from the latest formations of East Anglia to the traditional metamorphic rocks of the Highlands. Smith gave every stratum a unique color, based mostly loosely on the color of rock they indicated, and graded in order that the strongest color represents the bottom of the formation, lightening upwards.

One of William Smith’s maps (the Delineation of Strata, 1815) on display at the Geological Society in Piccadilly, London.
One among William Smith’s maps (the Delineation of Strata, 1815) on show on the Geological Society in Piccadilly, London. {Photograph}: David Levene/The Guardian

The colors Smith selected are, kind of, these nonetheless employed by all stratigraphers right now. They’re based mostly on the colors of the rocks themselves: yellow for the Triassic sandstone of Shropshire, shaped from scorching, dry deserts; pale pink for Cambrian granites extruded from prehistoric volcanoes in what’s now Wales; blue for the coal-bearing Carboniferous rocks of the Midlands, when that area was a land of seething, glistening swamps; pale, yellowish inexperienced for the white chalk, as a result of white would have proven up badly in opposition to the paper.

Smith’s map helped to form the financial and scientific growth of Britain throughout the Industrial Revolution. It confirmed the place coal to energy the factories is perhaps discovered. The place clays and rocks to construct the rising cities is perhaps quarried. The place tin and lead and copper might be mined. The place a canal or railway line may most simply be dug. His map represented a rise not simply in information, but in addition in wealth.

Smith is usually referred to as “the daddy of English geology”. In 2003, one among his authentic maps was bought for £55,000. In Piccadilly, the society that will as soon as have refused him membership shows his relics like these of a saint: an oil portray full with a lock of Smith’s white hair sealed into the body and two uncomfortable-looking wood chairs.

The research of chalk is what is usually termed “delicate rock” geology. Comfortable rock consultants research “sedimentary rocks reminiscent of sandstones and limestones, whereas their “exhausting rock” counterparts work on the robust igneous and metamorphic rocks reminiscent of granites and slates. The classes aren’t excellent, however the jargon sticks. Rivalry typically ensues. I as soon as met a retired sedimentary geologist who argued that “delicate rock males” are all the time the extra considerate. It got here, he mused, from desirous about the formation of sedimentary rocks. One rock unit shaped from the quiet accretion of layers of sediment over many thousands and thousands of years. The gradual, gradual formation of worlds. And what about exhausting rock geologists? I requested him. “Arduous rock males are all bastards,” he stated.

The chalk world started to come back into existence round 80-100 million years in the past, when the Earth was getting into a warming part. Seas rose quickly, and one third of the landmasses current right now disappeared beneath the rising waves. Geologists name this era the Cretaceous, after creta, the Latin for “chalk”, and it’s the longest geological time interval on the stratigraphic chart: at 80 million years, it lasted far longer than the 65 million years which have elapsed because it ended.

In areas the place chalk is discovered right now, the water was stuffed with billions of microscopic organisms referred to as coccoliths. After they died, their skeletons sank down via the clear water, in such amount that in locations the ocean would have turned a milky blue. On the ocean ground the skeletons piled up, forming a delicate ooze. Over time, this compacted and hardened – dwelling bones translated into white rock. The uniformity of the chalk – these large thicknesses of rock, some a mile in depth – is testomony to a steady, slowly drifting world the place, for thousands and thousands of years, nothing a lot occurred.

Through the late 19th century, geologists started additional refining the prevailing rock items of sort and time. However comparatively little consideration was paid to chalk. Geologists felt there wasn’t a lot to say about it, and little financial crucial to check it in better element. It had some use as a fertiliser and, later, in concrete, however it comprises no coal, oil, valuable minerals or metals, and is mostly too delicate to be a constructing materials.

Chalks cliffs at Beachy Head in East Sussex.
Chalks cliffs at Beachy Head in East Sussex. {Photograph}: Gary Yeowell/Getty Photos

Even amongst that subsection of the inhabitants who get excited by piece of rock, for years chalk was seen as pretty boring. When Farrant began work on the BGS in 1996, he instructed me: “I acquired dumped on the chalk and I believed, ‘Oh God, how boring.’ It seems I used to be mistaken.”

In Britain – or, extra precisely, the place that was to change into Britain – the following huge factor to occur to the chalk occurred about 50 million years in the past, when the African plate crashed into Europe. The land buckled up, forming a collection of ridges together with the Pyrenees and the Alps. In Britain, a collection of low chalk hills started to emerge from the ocean. At first they had been capped with mud and sandstones, however erosion finally did its work and shaped the naked chalk scarps of the South and North Downs and the Chilterns.

At the moment within the south-east of the UK, a lot of the chalk has disappeared beneath sprawling cities and suburbs, however the place it hasn’t been constructed over it produces a panorama usually considered as quintessentially English. Clean, rolling hills coated with brief turf. Mild slopes and steep escarpments, dry valleys and lonely beech hangers. Seen from a distance, it appears to ebb and swell just like the ocean from which it as soon as emerged.

On postcards and tea towels, pictures of chalk landscapes carry out a specific model of Englishness. “Chalk has fairly a central place in England’s cultural historical past – the white cliffs of Dover and all that stuff,” Farrant stated. “And but most individuals know nothing about what it’s and the way it shaped.”

On the fringe of the nation, the chalk turns into dramatic, unsettling. Standing on the seashore at Cuckmere Haven in Sussex, you lookup on the towering whiteness and it appears for a second as if it’s falling in the direction of you out of the blue sky. The uncovered chalk has one thing chilly and otherworldly about it. To see such whiteness, such brightness, feels unnatural.

From the south coast, the chalk runs beneath the Channel and reappears as one other set of white cliffs, which the French name the Côte d’Albâtre (“Alabaster Coast”) and the English have a tendency to not speak about very a lot. These had been a lot painted by Monet, Pissarro and Renoir. Chalk, which the English usually appear to treat as peculiarly their very own, lies underneath a lot of northern France, and bits of Scandinavia, the Netherlands and Germany.

Chalk cliffs on the Cote d’Albatre, or Alabaster Coast, near Etretat in France.
Chalk cliffs on the Cote d’Albatre, or Alabaster Coast, close to Etretat in France. {Photograph}: Prochasson Frederic/Alamy

In 1993, Richard Selley, then a professor at Imperial Faculty London, had been desirous about the similarities between the chalk panorama of the North Downs and the Champagne area in north-east France. His neighbour had been unsuccessfully attempting to farm sheep and pigs on his property within the North Downs. Selley urged he strive glowing wine. That winery now produces near 1m bottles of wine a yr, about half of it glowing – which might, if made in north-eastern France, be referred to as champagne.

As Farrant stated: “The English Channel is mostly a minor factor. It’s the identical deposit mainly, so there’s no Brexit with the chalk.”

The Chiltern Hills run for 46 miles from Goring-on-Thames in Oxfordshire north-west to Hitchin in Hertfordshire. At their highest level – Haddington Hill in Buckinghamshire – a stone monument marks the 267-metre summit. A lot of this panorama is farmland. There are small villages huddled deep within the dry valleys, historic market cities and the sides of suburbia. I joined Farrant and his BGS colleagues there on a heat day of blue skies and powerful, low autumn mild. Farrant and I set off with a brand new recruit referred to as Romaine Graham, who had been engaged on the chalk for 2 weeks and had blood blisters on the palms of her arms from wielding her hammer.

We adopted a observe between hedgerows stuffed with fats, pink rosehips and rambling previous man’s beard. We climbed over a barbed-wire fence between two ploughed fields; the place there are not any footpaths, the surveyors depend on the goodwill of landowners for entry. Farmers are often OK, however gamekeepers are usually territorial. By the sting of the sector, Farrant and Graham used their hammers to interrupt open items of chalk. “That is the Zig Zag Chalk,” Farrant says. “It’s medium-hard, pale gray and blocky.”

We all know now that the chalk was by no means simply the three giant, monolithic blocks of rock (and time) that the 19th-century geologists proposed – Decrease, Center and Higher. Within the 1980s, geologists started subdividing the chalk into 9 formations. As we walked, Farrant and Graham started to debate variations between formations. To the uninitiated, these can appear negligible. Working in chalk is all about getting your eye in, studying the subtlest of clues. The Zig Zag, for instance, they described as “quite boring, John Main gray”. The Seaford, against this, is delicate, clean and vibrant white, and infrequently comprises giant flints. The Holywell is creamy white, stuffed with small fossils. The Lewes is white, creamy or yellowish. Chalk rock may be very exhausting, nearer to the exhausting limestones of Cheddar Gorge than the delicate, crumbly white stuff that almost all of us consider as chalk. Every formation represents a unique world, and every of those worlds existed for a lot, far longer than people have been on the planet.

Wright here there should not many outcrops, the surveyor should discover different methods of getting on the chalk. You search for previous quarries and pits, badger setts, newly ploughed fields, and even graveyards, the place the earth has been just lately turned. Engaged on a web site at Stonehenge, Farrant discovered himself on his arms and knees on the lookout for molehills beside the roar of the A303. “Doing this work has acquired more durable just lately,” he stated. “Over the previous 10 years farmers stopped deep ploughing. Now they use one thing referred to as a no-plough technique, the place they only put the seeds straight within the floor, which is implausible for wildlife, however for us it’s a proper ache.”

Up forward he noticed a small copse, which he thought may comprise the stays of an previous chalk pit, and dived into the undergrowth. “We spend a variety of time combating via bushes,” Graham stated. “Andy loves it.” By the point we caught up with him, he was sitting in the course of the undergrowth hacking at a chunk of chalk. “Totternhoe Stone,” he confirmed.

Mapping the chalk additionally depends closely on what Farrant calls “panorama literacy”: the flexibility to find out what’s underground by finding out the floor. That may imply figuring out that rounded hilltops are usually Seaford chalk, and flat fields usually Zig Zag. Or that the place chalk is on the floor you discover beech, yew and holly, and the place it’s deeper there are pine timber, heather and gorse.

By early afternoon the sunshine had modified, and the fields glowed lavender and apricot. Up shut the soil was mild gray and dry, and the surveyors’ footprints regarded like they had been on the moon. The hill of Ivinghoe Beacon loomed above us – as soon as the location of a bronze-age barrow, then an iron-age fort – rising up abruptly from the Vale of Aylesbury to type a part of the ridge of the Chilterns.

A fish fossil in a block of chalk found near Dover.
A fish fossil in a block of chalk discovered close to Dover. {Photograph}: Interfoto/Alamy

As we started to climb, we handed an uncovered financial institution of chalk, created when the trail was reduce into the hillside. Right here the surveyors thought they may discover fossils. Graham lent me her hammer, and after 5 minutes we’d amassed a small assortment of long-dead sea creatures. Items of chalk break up in half to disclose a brown tubular worm, a brachiopod shell like a toenail, and the right spiral of an ammonite.

“What I actually love are hint fossils,” Graham stated. “They will inform you a lot.” Hint fossils are the stays not of the creature itself, however of its footprints, tracks, burrows or faeces. “Typically you’ll be able to see two tracks – possibly two trilobites skittering throughout the sand – and you may see the place they be a part of collectively for a bit, have slightly social gathering. It’s simpler to consider previous landscapes after I can see traces of the creatures that lived in them. You assume, wow, it was actually right here.”

Constructing on methods pioneered by Smith within the early 19th century, trendy surveyors use fossils and microfossils to establish layers of chalk. Again in 2002, Farrant instructed me, police referred to as on the assistance of native geologists when a tiny fragment of chalk was discovered beneath the wheel arch of the Soham assassin Ian Huntley. Two explicit microfossils had been found within the chalk: one discovered solely within the Seaford and one solely within the higher Newhaven. The presence of each microfossils meant that the chalk fragment may solely have come from a selected 2-metre thick layer – and the one place that chalk may have been pushed over was an area farm observe {that a} farmer had coated with that particular chalk, and the place Huntley claimed he had by no means been. The chalk fragment shaped a part of the proof that finally secured his conviction.

At the highest of the Beacon we sat down. It was very nonetheless and really silent. Someplace up above a skylark was calling. From right here you would see the fields of Buckinghamshire, Bedfordshire, Hertfordshire and Oxfordshire past. Within the distance a row of small bushes flamed yellow and pink, a line of fireside alongside the sting of the inexperienced subject. It made sense, I used to be pondering, that the primary folks to stay right here headed for this place, climbed up the hill to the place a view of the world opened out.

Graham ate a banana and stated that tomorrow she needed to attempt to acquire sloes. “It’s not all the time as nice as this,” Farrant warned me. “It is best to come again when it’s a freezing, raining day in January and we’re caught surveying some industrial property in Watford.”

Chalk tracks on Ivinghoe Beacon in Buckinghamshire.
Chalk tracks on Ivinghoe Beacon in Buckinghamshire. {Photograph}: Robert Stainforth/Alamy

He acquired out a laptop computer and commenced to enter information. The map they had been engaged on is funded by the Environmental Company and two main water firms. As a result of chalk is very permeable, it acts as an enormous aquifer, offering a supply of ingesting water. The chalk additionally acts as a pure filter, purifying the water that drains via it. However there are additionally fractures within the rock – and right here the water flows as a substitute of drains. Water firms have to understand how the water flows via the chalk, the place it may be safely extracted. And for that they want an correct, detailed map of the totally different formations. The Holywell fractures another way from the Seaford. A crack within the Newhaven just isn’t the identical as one within the Zig Zag.

When he’d completed together with his laptop computer, Farrant pointed downhill. “When you stood right here throughout the Anglian Glaciation you’ll have seen an ice sheet coming proper as much as the bottom of the chalk scarp there.”

The subsequent chapter of the story of the formation of the Chilterns came about round 450,000 years in the past, when immense ice sheets coated the north of Britain, reaching down so far as Watford. Past the ice, the Chilterns was a wild expanse of chilly, empty tundra. Unable to permeate the frozen floor, melting water flowed over the floor of the land, forming river channels that finally reduce down into the rock to create the dry valleys which can be such a particular characteristic of the chalk panorama. “The entire of southern England has been fantastically picked out by that periglacial weathering,” Farrant stated. Additional north, all the things was simply bulldozed by the ice. I pictured nice blocks of ice shifting remorselessly throughout a panorama – ice heavy sufficient to grind and clean away the very rocks in its path.

A few weeks after my journey to the Chilterns, I went for a stroll on the North Downs, on the opposite aspect of London. Following a farm observe in the direction of the ridgeway, the excitement and roar of the M25 was faint however insistent, just like the distant rush of the ocean. Underfoot the trail was pale brown and, the place the skinny topsoil had blown away, vibrant white – the bones of the land uncovered. Reaching the ridge, I paused, turned and noticed London within the distance. Gray and silver towers developing out of a muzzy blueness away over the beech timber and red-tiled suburban roofs.

As I stood there, trying again in the direction of the town, it appeared as if the blueness intensified. After which it regarded for some time as if the previous Cretaceous ocean had returned to the London basin. Or as if I used to be seeing a flooded metropolis a while sooner or later. I thought of melting ice sheets and sea degree rise and the way, as I stood there, the south-east of the island was sinking whereas Scotland rose up – a see-saw impact brought on when the good northern ice sheets started to soften round 20,000 years in the past.

After which, I imagined, the bottom within the metropolis would change into heavy like a saturated sponge, the groundwater seeping up between the paving stones, effervescent up out of the drains and working alongside the gutters. The Thames would swell and over-top its banks. Fingers of brackish water creeping up Cheapside and into the grounds of St Paul’s. The water rising over the Homes of Parliament, Massive Ben, the Palace of Westminster. A blueness overtaking the panorama.

Tailored from Notes From Deep Time: A Journey By means of Our Previous and Future Worlds by Helen Gordon, printed by Profile and obtainable at guardianbookshop.com

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