I wrote this essay as the Introduction to an anthology of writing about chalk-streams first published my Medlar Press in 2005. It still makes a good overview. I have added a few lines here and there. To understand a bit more of what makes a chalk-stream and what defines the subtle differences that exist from one river to the next I suggest you also take a look at my INDEX of chalk-streams and the pre-amble which explains the four broad classifications I have developed with Dr Haydon Bailey.
The Medlar Press book on Chalk-streams is still in print and can be ordered HERE:
“The story of chalk began in a much warmer world about 100 million years ago. Carbon dioxide levels were four times what they are today. The oceans over the British Isles were a tropical 20 degrees centigrade or more. The supercontinents of Laurasia and Gondwanaland were breaking up – the Atlantic Ocean was in the early stages of formation and sea levels were much higher than they are now. Kent was over 100 metres below the surface of the waves.
There were few mammals. On land mostly dinosaurs, and insects. In the sea rays, sharks and reptiles. Also a planktonic green algae called a coccolith. As the coccoliths died their skeletons sank to the sea-bed, and there mixed with the remains of bottom-dwelling molluscs of various types – foraminifera, ostracods, and ammonites – and the deposited layers of these skeletons built up over time to form chalk.
So prominent was chalk in the perception of the earliest geologists that it lent its name to the entire geological time-period – the Cretaceous (from the Latin creta meaning chalk). The derivation of the word chalk in English comes from the Saxon crealc, and the hard pronunciation of the word kalk is said to still be in use by some in Lincolnshire.
The Cretaceous period – and the accumulation of chalk – ended when a giant meteorite struck the earth near the Yucatan peninsula in Mexico. The collision caused giant tsunamis, which radiated in all directions, and threw enough dust into the atmosphere to cause a nuclear winter lasting for many years and global cooling on a vast sacle. Most animals including the dinosaurs were wiped out.
Chalk occurs all over the world in the Anglo-Parisian basin, running from Flamborough Head in Yorkshire to the coast of Dorset, and across the channel into Normandy in northern France. Some chalk occurs in the great Cretaceous deposits of Russia, and in Kansas, Iowa, Nebraska, Texas and S. Dakota in the United States. Hard white chalk occurs in Ireland in Antrim, and on the opposite shore of Scotland in Mull and Morven. There is chalk in Australia and Israel.
But it is only in England and Normandy that massive chalk deposits and a temperate climate have coincided to give us chalk-streams as we know them: a globally unique ecosystem.
The reason is subtle, but crucial: only in this Anglo-Parisian basin is the chalk close enough to the surface to create the kinds of rivers we know as chalk-streams.
There might well be chalk across great swathes of the Ukraine, for example, but it is buried deep under peri-glacial drift or younger layers of sand, mud and clay. In England and France the chalk layers deposited in shallow seas during that Cretaceous epoch have been lifted to the surface and polished clean by glaciers, but they have not been worn away. It is this clean but intact chalk-downland and our rain-swept landscape and temperate climate that gives us chalk-streams as we know them.
There might well also be rivers throughout the world that look like chalk-streams: but that doesn’t mean they are. Limestone streams are very similar. Limestone is chemically identical to chalk, it is also made up of the remains of tiny sea-creatures. But generally it is much older and harder and it is rather less soluble. This makes a difference to the flow regime, and the PH and to the landscape across which the rivers flow. Chalk-streams flow through softer downland: their gradients are shallower, their flow regimes more equable.
Chalk-streams form when rain falls on chalk down-land and seeps through fissures in the rocks, coalescing into trickles and rivulets. Where the fissures have widened with erosion the rivulets may even gather further to form underground streams. A chalk aquifer is not so much an underground body of water, as a saturation of all the fissures, through which the water flows. This hidden migration of water is of unknowable complexity. Layers of marl and flint interrupt the chalk, and where they do water can flow laterally along these seams for miles. The seams may run counter to the hills above ground. Water may flow in one direction along one seam, and in another along a seam below that. Surface rivers are fundamentally two-dimensional, but to envisage the workings of a chalk aquifer we need to think in three dimensions, to imagine water flowing like marbles through an Escheresque jumble of tunnels.
Over millions of years these subterranean inclines have in places concentrated the erosive action of the water to form chalk valleys. And in these valleys where the aquifer fills in winter – imagine a leaky bucket overflowing – or where it rests on a bed of marl and flint, water emerges as springs and a chalk-stream is born.
Coleridge wrote some lines that evoke the birth of a chalk-stream
Unperishing youth ! Thou leapest from forth
The cell of thy hidden nativity;
Never mortal saw
The cradle of the strong one;
Never mortal heard
The gathering of his voices;
The deep-murmured charm of the son of the rock,
That is lisp’d evermore at his slumberless fountain.
I know places like this: a path in Dorset runs along the foot of a chalk escarpment between woods and the River Stour. In winter after heavy rain dozens of springs burst at the foot of the slope and run across the path to the river. In one place the springs break underwater in the river itself. The bank has fallen away, undermined by the erosion from within, and when the Stour is coloured this spring clears a hole in the opaque water like a view through to blue sky on a cloudy day.
Further west in another valley a wood grows around a hollow in the sloping land where springs break through the roots of beech trees and collect in a pool. The pool spills over a derelict hatchway, and forms a stream that runs across a farm track. At dusk in mid-winter the stark trees are like black bars against the glowing western skyline. The sounds of rooks and tumbling water underline the isolation and quietness of the place, the hidden nativity of a chalk river.
I became fascinated by chalk-streams long before I saw or fished one. I had a book on angling, and in a section on trout fishing found a colour photograph of a chalk-stream. Though I’ve lost the book I have the picture in my head: high summer, a bright day. Trees overarch the river. Alongside the river is a meadow full of wild flowers, and heavy tussocks of grass. A thatch-roofed hut is in the background. The stream runs towards me from a row of hatchways. It is blowsy and clear. Patches in the weed show clean gravel between. Was there a trout in the picture, or did I place it there? I used to fish that river in my imagination.
Now I fish rivers like it for real and I find the foundations of that first captivation remain the same.
In a more famous poem Coleridge places a spring-fed stream inside a walled pleasure-garden, ‘Where Alph the sacred river ran’. The stream is wild – it meanders, and at its springhead it rises in tumults like a volcano. But the romantic power of the poem comes partly from the relationship between this river and the pleasure garden. The wild is set beside the man-made, and each gives something to the other: the tamed wildness; the works of man placed in context.
The hut was significant in that picture, and now that I know more about more chalk rivers, I realise that so was the shape of the channel, its relationship to the meadow, the hatch mechanism through which the water spilled, the stately spacing of the trees. Chalk-streams are not only inseparable from the works of man; they are largely man-made. This particular relationship is vital. It gives the rivers an aesthetic whole. It makes them enchanting, soothing places to spend time.
It’s difficult to find a painting by Claude, Constable, or Turner in which the natural world is not offset by something of man. Turner’s most vaporous scenes need a castle or a mast. In Claude’s classical landscapes a bridge, boat or a thoughtful shepherd metre out the rhythm of the scene. Constable painted the chalk-streams of Suffolk: the sluices and mooring posts of his paintings do the same as the hut and the hatchway in that photograph: they set up an aesthetic tension and balance.
That same balance is what makes the sight of water spilling through a brick and timber hatchway so satisfying. Better still if the hatch is derelict, if the bricks are crumbling and if brambles overhang the white water at the head of the pool – a hint of Romanticism. In the Classical tradition man harnesses nature, in the Romantic he is overcome by it. There is a bit of both in the beauty of a chalk-stream.
This aesthetic balance is not unique to chalk rivers, but it is heightened in them. Chalk rivers are by their nature so malleable. They don’t flood; they don’t dry up. They flow through gentle, habitable countryside: an epicentre of human development since the Romans.
Pre-historic chalk-streams would have flowed through wetlands dense with willow, alder and sedge, braided into channels. It is difficult to find a chalk-stream today in this state, though the headwaters and isolated sections of some streams get close. I know several spots where rivers flow through unkempt woodland and the channels braid. Where springs enter a main river – there’s a place on the Frome above Dorchester, another on the Itchen close to Winchester, another near an old Priory in Norfolk – and where there has never been a reason for harnessing and channelling that flow, the braided, wild-wood stream can remain.
For the most part though the wet woodland was cleared for agriculture, the process beginning over two thousand years ago. And since the Roman occupation chalk-stream river channels have been progressively modified. Romans used the Lea as a navigable route to Verulamium, and in 1430 in the first known example of money borrowed by a statutory body for a public work, commissioners were given the power to remove the many obstructions or ‘shelfs’ along the course of the Lea. The Domesday book refers to thirteen mills on the River Wandle. Castle Acre priory was built with stones floated upstream on barges on the River Nar, a tiny Norfolk chalk-stream.
In the early 17th century a conduit of drinking water for a burgeoning London was constructed to flow from the springs of the Lea into the middle of the City – the New River. An attempt to do the same to the Wandle was defeated by the millers. Navigational canals were built alongside some chalk rivers. A plan to navigate the Avon to Salisbury was abandoned in the 1660’s, but later rivers like the Driffield, Kennet and the Itchen all had navigational canals built alongside them.
Water mills – fulling mills and flour mills – also changed the channels, each mill creating an impounded headwater, a mill pool and mill race.
In the grounds of stately homes streams were opened to form broad-waters and lakes in the craze for landscaping that gripped the moneyed classes of the 18th and 19th centuries. At Wilton the River Nadder is grandified and flows under an extravagant Palladian bridge.
Most distinctive was the harnessing of chalk-streams to create water meadows: a system of agriculture developed between the 17th and 19th centuries that shaped these rivers into a patchwork of channels, sluices and hatchways. Side streams or carriers were cut off the main channel forming a loop around and through the surrounding meadows. Hatchways were built to control flows into and out of this network of carriers, and cuts were made across the meadows to carry water to flood the ground: the flooding was intended to protect grazing meadows from frost and to fertilise the ground with sediment.
All of these developments dramatically shaped our chalk rivers and we fish amongst the relics – the hatchways and broad-waters, the maze of carriers that on rivers like the lower Frome, or the Kennet divide the floodplain into a complicated web of water.
But if the works of man set the scene, they have also undermined it.
The changes that have overtaken the chalk-streams since the mid-19th century while less visually dramatic for the most part, have unfortunately been more pernicious. The rivers of London felt some of the worst of them first: pollution and abstraction. The Wandle was once so great a river that Royal Preserves (1606) protected its fish stocks. Nelson fished it with his good arm. Walton referred to the trout spotted like tortoises, and Camden in 1586 to the ‘cleare rivulet Wandle, so full of the best trouts’.
Nature holds on with some tenacity. In 1805 according to Malcolm’s Compendium of Modern Husbandry, the Wandle supported twelve calico works, nine flour mills, five snuff mills, three bleaching grounds, five oil mills, two dyeing works, one paper mill, one skinning mill, one logwood mill, one copper mill, one porter brewery: forty-two industries in eight miles of water employing 3000 people. Trade was so brisk that the Wandle was the site of Britain’s first pre-steam rail-route, the horse-drawn Surrey Railway.
It remained a good trout stream for some time. A description of the river at Croydon in 1830 refers to the ‘nice gravely bottom for the trout to spawn in’ (that part of the river is now buried in a pipe). Halford caught his first dry fly trout on the Wandle at Carshalton in 1868, but forty years later the river was described as “sage-green and sluggish, a sticky stream soiled by a dozen factories and smelling vilely.” In 1934 its last trout was caught by a bait fisherman – a 5lb 2oz trout, 22 inches long. Industrial pollution, sewage from the suburbs and the intensifying effects of abstraction and the urbanisation of the catchment had finally contrived to kill the river.
In the 20th century a sprawling suburbia and its growing satellite towns demanded more and more water and the chalk aquifers of the Chilterns and North Downs supplied it. Drilling technology improved and boreholes were sunk deep into the ground. Rivers like the Chess, Misbourne and Darent are shadows today of what they once were, their aquifers denuded by the water pumps.
The effect of abstraction spread outwards as the heavily populated south and south east demanded more water. Today there is hardly a chalk-stream that does not feel the impact of abstraction. In some cases the impact is deadly. In 1995 I spent two weeks in July rescuing trout from a drying River Tarrant in Dorset. Eventually the river disappeared, all the way to its confluence with the Stour. When once our small chalk-streams would have survived a drought, the same conditions now can finish them off.
On the River Misbourne from 1962 until 1997 65% of the available water was pumped for public water supply. So extreme was the impact that in 1997 over 23km out of 25 km of river ran dry.
On the River Piddle at Briantspuddle – right on top of the cone of aquifer depression caused by the pumping station – the river has sometimes disappeared in hot dry summers. Now compensation water is needed to keep the stream going.
The compounding effects of abstraction – even when rivers do not dry completely – are severe. Pollutants become concentrated. The rivers slow down and drop sediment. Habitat for fish, insects and plants is reduced and severely altered. Any other negative impact on water quality – fish- or cress-farm pollution, sediment and nitrogen input from agriculture, phosphate input from sewage – is greatly increased by abstraction.
The population growth demanding water from the chalk downs has unfortunately coincided over the past 50 years with a second agricultural revolution – the post-war intensification of farming. In the decades following 1945 more and more land was brought into cultivation, more and more chemical fertilisers were applied to it and, perhaps worst of all, many rivers were dredged in agricultural drainage schemes, or so-called flood prevention measures which have since been shown to be poorly conceived and even counter-productive.
Between 1931 and 1991 the population in the Kennet valley grew from 55,000 to 175,000. The numbers of sheep and pigs increased massively, and the area cultivated for cereal crops trebled. Phosphorus inputs nearly trebled, and nitrogen inputs more than doubled. The combined input of nitrogen mostly from farming, and phosphorus mostly from sewage, and the intensifying effect of abstraction has brought on unpleasant changes to the ecology of our chalk rivers. Blanket weed and filamentous algae smother the gravels and river weeds on which the health and habitat of the river largely depends. Instead of deep, clear water flowing over clean gravel between stands of water buttercup, we get insipid opaque trickles over a slimy carpet of green ectoplasm.
As more land has been brought under the plough, and flows have weakened, so our chalk rivers have begun to choke with silt. Silt smothers the gravel on the river bed, smoothing over and blocking the rough texture, and spaces between the stones on which rooted plants and insects depend. Silt blocks the flow of water through the gravel redds cut by trout, grayling and salmon, suffocating their developing eggs. Silt feeds the algae with nutrients. Now autumn ploughing threatens to accelerate the rot. Rivers like the Upper Frome in Dorset are carrying far too much silt and appear to be losing their ability to sustain healthy numbers of wild trout.
Where livestock is farmed intensively cattle and even sheep can destroy river channels, treading the delicate margins into a dust bowl. When riverbanks lose the protection of plants they erode quickly. The channel gets wider, the river shallower, the water warmer. Badly poached rivers can became barren wastelands.
Invasive foreign pants have the same impact as herds of cattle. Himalayan Balsam, first imported by Victorian gardeners, thrives on our chalk-river banks. It has a sweet odour and pretty flowers but it is rampant and grows in dense patches, excluding all other plants. It colonises river-banks, but as an annual dies away to nothing in the winter, exposing bare earth to the erosive impact of winter flows.
While phosphorus and nitrogen inputs, and even abstraction can with a will be reduced in time, the work of the dragline and digger has wrecked many chalk-streams forever. It is abomination that so many miles of chalk river were dredged. Chalk-streams are not high-energy rivers. They have acquired their gravel and flint beds over millions of years, and once removed there is little chance of new material entering the system. But a living river needs its gravel like we need oxygen: the whole fluvial process depends on the relationship between flowing water and the material it moves around and over. Take out the gravel and you break the back of the river. Long reaches of the Lower Frome in Dorset are dispirited canals, with silt troughs for a bed. English Nature funded a small project of mine in 1999 to reinstate three gravel riffles, and the results on those few yards show that reparation can work. But such efforts will be sticking plaster until a will exists to restore to these rivers the full amount of material that was taken out of them.
After such a catalogue of debilitating impacts it is a miracle to consider that our chalk-streams are not completely destroyed. It has been their saving grace then to be such fine fishing streams and to have had as a result a passionate army of defenders. Anglers. Anglers have cared enough to observe and take note. They have also cared enough to act. In recent years it has been the anglers on these rivers who have agitated for reductions in abstraction, for gravel to be re-placed, for dredging programmes to be abated, for fly-surveys to be conducted, for phosphorus strippers to be installed at sewage works, for river banks to be fenced, for rubbish to be cleared from urban streams, for city-centre conservation projects, for miles of river bank to be restored, for invasive plant impacts to be taken seriously, for sediment inputs to be assessed, for more responsible agricultural practice, for government enquiries into the impact of cress farming and for the river corridors to be preserved. Anglers could rightly claim to be at the vanguard of efforts to save these unique rivers from the panoply of destructive influences the last 100 years of development has brought to bear, and as a result public trusts and governmental bodies have now taken up the cause with some enthusiasm.
But anglers still have one boil of their own to lance. In 1905 Plunket-Green wrote passionately of the folly of overstocking a wild stream in ‘Where the Bright Waters Meet’. In 1993 Sidney Vines wrote in The Field of widespread stocking practices that were greedy and disrespectful to both river and fish. The intervening years had taught us little. There is a delicate balance of course, and in many cases careful stocking is used to overcome some of the ways in which our chalk-streams have been undermined whilst still preserving a fishery. But trickle stocking to maintain sport and the benefits of a viable fishery is one thing. Swamp stocking with outsized fish calculated to satisfy the soulless trophy hunter is another. It is a curiously pointless exercise angling for a huge trout that only got huge on trout kibble, but more significantly poor stocking practise undermines the viability of what wild trout populations we have left.
In 2004 the Environment Agency published its Trout and Grayling strategy, which threatened to bring more careful controls to bear on the stocking of wild trout streams. The writing is on the wall. Anglers must clean up their act before it is cleaned up for them. (since writing this the EA has introduced a rule to allow stocking with only infertile (triploid) trout, and much more significantly the wild trout and wild rivers movement has made great strides. We are stocking less and less.)
Durnford’s fishing diary of 1809 makes interesting reading in this context. Trout caught in May of that year on the river Test averaged just over a pound. During ten years Durnford caught trout over two pounds in mayfly time, and the occasional three-pounder, nothing bigger. But today on some beats of the same river a three-pound trout would be the smallest fish in the bag.
If I try to think of the perfect trout stream I know that it is a chalk-stream. Limestone streams are more widespread, and often flow through less spoiled parts of the world but a chalk-stream at its best is unbeatable. All the qualities of a spring-fed river – constant, equable, cool, fertile – are magnified in a chalk-stream. Chalk-streams have a constancy that spans the seasons, they have a verdant opulence that the rougher-edged limestone stream cannot match, a sedate grandeur too. In this limpid environment of marbled currents wild trout thrive, growing fat and fantastically fussy.
But if I know that it is a chalk-stream I falter when I try to say which one. I think of all these qualities, and wonder where they meet their fullest expression and I hesitate. Not because there is such variety – which there is – but because nowhere is a chalk-stream flowing quite as it should be. And so this essay is a plea for their restoration and preservation.
A sickle shape of chalk rises the other side of the English channel in Normandy, drops under the sea, reappearing in Dorset buckling like waves against a reef. The waves gather height as they ride north and east through Wiltshire, Hampshire, settle to an easy swell through Berkshire, and furrow gently around the north of London, until as the swell rides out on the flat plains of East Anglia, the ripples are as gentle as the farthest reach of surf on a sweep of flat sand. Then the chalk is gone, though it surfaces again as an echo further north in Lincolnshire, and then again in Yorkshire. Right along this bed of chalk there are chalk-streams – hundreds of them. Far more than most who know chalk-streams well would guess. We think easily of the famous dozen or so, the Test, Itchen, Wylye, Avon, Kennet and so on. But who’s heard of the Jordan, Snail or Hun?
The fact that there are so many more than we would have suspected should be encouraging when we consider their condition. But ironically it only goes to underline that the chalk-stream is a finite thing. There are only so many and God is not making any more of them. The fact that not one mile of their globally unique habitat is as it should be ought to worry us, not least because it is a failure that belongs to the current generation.
The writing in this book is in collective praise of the chalk-stream. My small hope is that it will encourage one or two more pumps to be switched off, or one or two hundred tons more gravel to be put back.
Charles Rangeley-Wilson, Norfolk, January 2005.”