The men who first found those seams and named them—after their favorite pub, perhaps, or a girlfriend, or a hill immediately above the mine—are long dead now, and such histories as have been written of the coalfield give the Mearns Pit, one of the lesser collieries in commercial terms, short shrift indeed. But when the last truckload of coking coal left the last mine in Radstock for the Portishead Power Station in 1973, it was from one of the deep seams of the field, nine thousand linear feet in absolute terms* below the red earth that lay serenely and unconformably above the contortions of the coal.
The stratigraphical order in which the different types of rock were arranged in the coalfield, as the local miners knew and as William Smith learned from them all too rapidly, had an utterly predictable regularity to it. Smith would see and come to know the strata intimately as he saw them one by one, again and again, as the great winding chain lowered him still further down through the measures.
First there would be the sandstones themselves, with strange patterns of bedding about them. Some patterns were large and reminiscent of dunes, other patterns were small, like the ripples to be found on the beds of river estuaries. After a few dozen feet, the sandstones would peter out and be gradually replaced by argillaceous beds of more thinly bedded rocks, with finer, darker grains—muddy and silty, solidified versions of what one might find on the bed of a shallow river. Next there would be a bed with fragments of shells, recognizable as the kind of bivalves, Carbonicola and Anthracosia among them, that are found in rivers and abhor the dissolved salts of the sea.
Then there would be mudstones—softer, dark, friable rocks, suggestive of—well—solidified mud. Next, an indicative precursor of what would come next, there would invariably be a thin band of lighter-colored, harder rock stuffed with shells of a salt-water brachiopod like Lingula—a creature still to be found more or less unaltered today, which lives today as Carboniferous Lingula did 290 million years ago, happily and resolutely among the salt and the wavelets on the seashore.
And below that—the coal. The seam might be the Globe or the Perrink or the Kingswood Toad, and whether it was nine inches or nine feet thick, it would always be overlain by the same facies and underlain by the same seat earth. However, and most important for the ever-observant William Smith, each seam would be subtly different: It might be colored richly and deeply black, it might be oily, flammable, stiff with flies and footprints and the relics of eminently burnable fossil vegetation—Mariopteris, Annularia, Lepidodendron—and then, suddenly, cut off in a matter of fractions of an inch, the whole black band would be underlain by a light band of nonflammable seat earth, in which once all the ferns, trees, and horsetails placed their roots and from which they gained their sustenance.
The pattern, Smith saw, was always the same, in mine after mine after mine: from top to bottom, Sandstone, Siltstone, Mudstone, Nonmarine Band, Marine Band, Coal, Seat Earth, and then again Sandstone, Siltstone, Mudstone, on and on. On top of everything, placid and unconformable, the red marls, the flatly sloping beds of the startlingly red red earth.
And through all of this, in mine after mine, in quarry after quarry, what was perhaps the most crucial realization of all in this time of early, primitive discovery—the fact that recognizable seams of coal would always be in the same position compared to one another. The Dungy Drift—identifiable by its thickness, its color, and its fauna and flora—was always above the Perrink. The Rudge was always above the Temple Cloud. Never once—unless the Variscan folding has turned the whole bedding upside down, and a skilled observer could always tell if a rock bed was the right way up or not—would the Slyving be anywhere other than above the Great Course and the Firestone. It would always be well below the Withy Mills Seam and what the miners had christened the Pensford Forty Yard.
And that, in essence, is what William Smith first learned, both from the miners that he met and from the sections of the underworld that he saw. He understood for the first time that geology was a science requiring observations in three dimensions. He could make maps and make surveys of the visible upper dimensions of the landscape with ease—anyone with a modicum of a skill could do that. But to see below the surface, to observe or extrapolate the imaginable third dimension underground—that was a new skill, possessed by very few, and yet that had a potential that Smith was soon going to recognize and exploit.
The Somerset Coalfield.
But first he had to grasp and set down on paper the importance of what he had just seen. He pondered on what he remembered; he pored over his notes. And he promptly wrote down in his diary what it was that he realized—that to judge from what he had seen at all these pits around his farm at Rugborne, he could make a firm pronouncement about the nature of sedimentary rocks—a pronouncement that he suspected had never been made before.
In his opinion, he wrote, all the rocks that had been laid down as sediments at a particular time in a particular place are laid down in a way that has much the same characteristics, and most particularly just the same fossils, and always appear in the same vertical order, in the same stratigraphical order, no matter where they are found.
He clarified his theory with examples. The coal measures in the south of the Somerset coalfield, near Radstock, for example, display a specific order. There is a Sandstone, a Siltstone, a Mudstone with Carbonicola, another Siltstone with Lingula, then the four feet of the Temple Cloud coal seam, back to Sandstone and Siltstones and then the Newbury No.2 seam and the Globe seam.
Using Smith’s new theory it would be possible, by noting the types of fossils he found, to forecast, and then to confirm, that ten miles to the north, at High Littleton, there would be exactly the same order. The Temple Cloud coal with its fossils would be lying above the Newbury No.2 with its slightly different ferns and fossil leaves, and the Globe with its peculiar collection of once-dead inhabitants would be down at the base. In between would be just the same Sandstones and Mudstones, just the same Carbonicolae and Lingulae as back at Radstock. Perhaps not the same thickness. But always, always in the same order. Never—if the beds were lying right side up—would the Globe be at the top, never would the Lingula be found above the Carbonicola.
Such an order of strata would be repeated also in other places that had never yet been explored. The order would be repeated also in mines yet undug. It was an order that could be well and accurately predicted. The fossils would be the key to working out what the order was. Using them, one could forecast the precise succession of the beds underground. And if they could be forecast, they could and would eventually be mapped.
This was true for the coal mines of High Littleton—of that much William Smith was now certain. Yet at the same time as he was realizing and understanding all this, Smith began to wonder: If what he had found was true for the seams, facies, and lithologies of all the rocks that he and the miners had found lying below the red earth—might it not also be true for all the rocks, for the Limestones, Oolites, Shales, Clays, Cherts, Marls, Sandstones, and Silts, that lay above it? And might it not be equally true, too, for rocks so far unfound, and which would presumably lie underneath the coal? Was not this predictability of strata likely to be a universal phenomenon?
The miners said no. Smith records their instant rejection of his theory matter-of-factly. “The order of superposition in the Coal Measures at each pit seemed well enough known to the colliers,” he wrote in his diary,
and on drawing a section thereof with nine veins of coal I was naturally led to ask whether the superincumbent strata, rising into hills two hundred to three hundred feet above the mouths of their coalpits, were not also regular. I was told there was “nothing regular above the Red Ground,” which in their sinkings varied much in thickness. This did not deter me from pursuing my own thoughts about this subject.
It was just as well that he was not deterred. He thought about the miners a little more closely. He felt he could understand why, out of a mixture of protection and plain ignorance, a miner might insist that these particular
patterns and fingerprints of rock successions that Smith had recognized were confined to their own rocks, to the coal measures of the Upper Carboniferous, and would not be reproducible elsewhere. He might understand the miners’ motives—but what they said made no sense at all.
Wasn’t it more likely that some similarly arranged succession of strata was actually to be found among all the rocks of England, whether they were above or below the coal? Whether they were younger or older than it? And further, wasn’t it likely, if this orderliness of succession proved true elsewhere, that someone with a good eye and a good imagination could find the arrangements and the possibilities for identifying and following unseen strata, the hidden underground strata, among all the rocks of the world?
Might there not thus be some way of predicting what lay where, how deep it lay, how thick the beds were likely to be, and what might lie above and below it? And thus, might there not be a way of drawing a guide to this hitherto hidden underneath of the planet, in much the same way one drew guides to the visible world, to the simple topography of the overburden?
Had he not, in thinking so, stumbled onto an original, fundamental truth? Wasn’t it likely that everything he had reasoned for the rocks at High Littleton was true for everywhere else as well? And if it was, then wasn’t it likely that everything geological, everywhere—whether it was underground or overground, whether it was deep or shallow, whether it was visible or not—could be predicted, could be drawn, and thus could be mapped?
New observations were needed. More data, more facts, more work, below and beyond the very special world of the coal mines, beyond the age-limiting, fossil-limiting, lithology-limiting purlieus of the Carboniferous. William Smith needed a bigger canvas on which to sketch the first portrait of what he was now nervously beginning to imagine.
And it was then, thanks to connections, location, and coincidence, that William Smith stumbled onto the chance that made him. The coal from Somerset’s dozens of mines needed to be moved. The perfidious Welsh across the Avon, having caught the duke of Bridgewater’s fierce mania, were reported to be building a canal and getting ready to move their coal along it—and suddenly all Somerset was fretful, its miners and mineowners concerned that the county might lose out to Wales, that its coal would never get to the markets. A great Somerset canal urgently needed to be built.
William Smith, who was by now an established master of all the local mysteries of coal, a clear and present friend to the local landed mineowners, and known to be clever with the theodolite, the plane table, and the chain, was the ideal man to be involved. He knew how to carry out a survey. He was obviously the man to plan the route, to make sure the canal snaked properly from coalfield to market. William Smith, it was decided, should be the Somerset Coal Canal’s first surveyor.
He accepted the job with almost unseemly relish. He had a motive that he never vouchsafed to his new employers. Not only were the wages excellent, the perks more than acceptable, and the possibilities of share options in the new canal tempting—but the process of building a canal meant that, quite simply, a great swath of the county needed to be sliced open, cut neatly and deliberately in half.
And in the process of cutting the land he might be able to confirm his theories, and see if that original and fundamental truth was indeed a truth at all. By slicing open this vast line of survey, and then building a deep canal halfway across the county, the land itself would for the first time be exposed. It would be laid bare and fresh for Smith to see, to examine in detail, and to wonder if he might, just might, be right.
Right in thinking, that is, that one could tell which strata were which by their nature and by their enclosed fossils. If one could do that one could, in theory, find and identify the outcrop of a particular stratum in one place, and then find and identify it in another place and another, and before long be able to draw a map, from which it would then be possible to extrapolate, with accuracy and speed, the position of that stratum as it snaked through the entire English underworld.
One could do it for one stratum or, with patience, for all strata. One could then draw a map of the underneath of England just as readily as one could map the overground. And if it might be possible to map the underneath of England, then by extension one could make a map of the hidden underside of the whole wide world beyond.
It all depended, though, on his making one so-far-unmade discovery: He needed to find that the aspects of rocks that were so recognizable within the patterns of the coal measures, occurred just as well in the rocks that lay above them. The miners were skeptical. But William Smith was not. He believed that there would be a pattern out there. He needed simply to lay open a great slice of English countryside and see for himself, firsthand. The new canal would be his one opportunity for doing so.
6
The Slicing of Somerset
Sonninia sowerbyi
The British have an unrequited love affair with their railways. The older, the more obscure, the smokier, the more inefficient, and less commercially successful they are, the better. Dr. Richard Beeching, whose infamous 1965 report resulted in the closure of five thousand miles of old, inefficient but much-loved track and the attendant two thousand railway stations—most of them wrongly remembered as cottagelike and fretworked, with endlessly congenial stationmasters and rose beds planted on the platforms—is still regarded as a villain. The evidence of Beeching’s savagery—abandoned lines now swathed in grass, old bridges rising over emptiness, stations now turned into houses or small factories, or left to rot—remains everywhere. And whole communities in remote and pretty parts of Dorset, Cumberland, Norfolk, and Yorkshire curse him yet, as the man who ruined forever an enchanting and supremely British way of life, along the country railway.
The Camerton & Limpley Stoke Railway, in North Somerset, was as pretty a railway as they come. It was known by local schoolboys, and for obvious onomatopoeic reasons, as the Clank. Its economics, however, made no sense at all, right from the moment it opened for business in 1907. Its tiny income—from a dwindling number of coal mines, from a mill that packaged wool dust, and from the carrying of luggage to and from a boys’ school—doomed it to extinction even before Lord Beeching had the opportunity of getting his hands on its seven miles and seventy-eight chains of track. The last fare-paying passenger traveled on the morning after Valentine’s Day, 1951.
But the Clank was memorialized in the minds of many million of Britons of my generation because it starred, though unrecognized by most who saw it, in one of the most successful British films of the time. It was called The Titfield Thunderbolt, and it was a comedy, made in 1952. It told the story of a line that was due for closure but might be awarded a reprieve if it could show that it could be run, by the villagers who depended on it, with greater efficiency than a competing local bus service. The train was run by a team that included the vicar, the local squire, and the ladies of the Women’s Institute. The bus, by contrast, was owned by a pair of curmudgeonly and profiteering blackguards from a grim slum town nearby. Who won and who lost I will leave for those who have not seen the film; but for this account of William Smith’s life, the story of the film is less important than the setting in which it was made.
The Camerton & Limpley Stoke Railway.
For The Titfield Thunderbolt was filmed in the valleys of the Cam and Midford Brooks, at the eastern end of the Camerton & Limpley Stoke Railway, in countryside that was—and still is—as lovely and as unmistakably English as any landscape imaginable. The film seemed then, and still seems in its time-warped look today, to be set in the middle of some kind of utterly English Elysian fields, where all is sun and lush meadows, babbling brooks and thatched cottages, village greens and cricket matches. On all sides there are comfortable pubs and ample barmaids; the people are by and large sturdy and honorable. The soundtrack drips with a fine nostalgia: There is birdsong, and there are steam whistles, we hear a milk churn being loaded, the flap of a porter’s flag, distant peals of church bells, the lowing of dairy-ready c
attle, and behind it all, as bass continuo, the amiable chuff of steam engines as they amble through cuttings and over level crossings and bustle back down the valleys to their sidings and their home.
But this is no fantasy of an imagined Englishness. The railway may have gone, but the world in which the Thunderbolt used to run is still there, south of Bath. It has been preserved in some kind of Betjemanesque amber—a patchwork of landscape six miles long by three miles deep, between the river Avon in the east and the village of Combe Hay, halfway westward along the long-disused railway line.
But its beauty peters out very quickly, and with sudden drama. To the west of Combe Hay the land becomes much less interesting, less pretty. A passerby in the train, were it still running, would—if traveling westbound—notice the change most easily, would see how the rural idyll between Limpley and Combe becomes slowly more tinged and tainted by the first indication of industry, of smoke, grit, iron, and rust. By the time the engine reaches Dunkerton, a couple of miles on, the smell of coal dust hangs in the air, and by the next station, Dunkerton Colliery Halt, there is (or was—it has long been demolished) the winding gear of a mine. And then from there to the west all is coal, all is industry, all is grim. It takes a small effort of imagination to recall that only ten miles back down the line, back to the east of Combe Hay, there was pretty landscape—landscape of a loveliness from another world.
The reason, as so often, is the geology. The hills around Combe Hay and Midford Halt, by Midford and Limpley Stoke itself, are the outcrops of what is called Bath stone, a warm, honey-colored oolitic limestone of the Middle Jurassic. A reporter for the Somerset Guardian understood this well when, in May 1910, he wrote of a railway journey that “there is not a more prettily situated line in the locality of Bath…the run through the Oolite from Combe Hay to Monkton Combe is the most interesting part of the track, because the traveller has lovely views all the time.”
The Map That Changed the World Page 8