Nature Studies by Michael McCarthy: Chalk – the great giver of wildlife richness


I have a great fondness for maps. I buy a map whenever I travel anywhere and I keep it, and I can browse through maps like you can browse through magazines, letting the imagination wander over this river and that wood, or this village and that lane; but my favourite map doesn't have rivers or woods marked on it, or villages or lanes, although, very faintly, it does have major towns.

It is "the 10-mile map" – the British Geological Survey's geological map of Britain, at the scale of 10 miles to the inch, which shows the country not in terms of administrative regions, or landscape features, but in terms of the underlying rocks. The various strata are variously coloured, for differentiation rather than resemblance (although the dull orange marking the Triassic sandstone of the Wirral peninsula where I grew up is remarkably similar to the stone itself), and what excites me whenever I unfold it is the great brilliant band of emerald green splashed diagonally across England from bottom left to top right, from Dorset to the East Riding of Yorkshire.

It is the chalk. The green on the map represents the soft white rock of the chalk hills, from the Dorset Downs up through the Chilterns to the Lincolnshire Wolds and beyond, formed from the remains of trillions of tiny organisms which filled the seas when the dinosaurs ruled on land, and settled on the seabed when they died.

It is pure calcium carbonate. It's not often celebrated. Perhaps that is because chalk as a substance may seem familiar and banal; it is for writing on blackboards or coating the ends of billiard cues. Yet chalk in the landscape is anything but; it is the great giver of beauty and wildlife richness. The chalk hills, often referred to as downs or downland, are what is most typical of the loveliness of the southern English countryside, as their form is gentle and flowing (like the contours of the human body, it has been said), quite unlike the paternalistic craggy dominance of the mountains of Wales and Scotland.

Even more, they host the best of our biodiversity. The flora of the chalk is stupendous, not just for the flower carpet of the short-cropped downland filled with scented wild thyme and horseshoe vetch and milkwort, and the chalk grassland flowers on Salisbury Plain such as wild marjoram and rock rose, but also for the rarities: a large number of our most uncommon and most spectacular orchids grow on the chalk, from the military orchid (once thought extinct in Britain) and the monkey orchid, to what may now be our most endangered wild flower, the red helleborine, blooming in a few secret places in the shadows of the Chiltern beechwoods.

The insects of the chalk landscapes are no less special: a wonderful assemblage of bumble-bees, and a heart-stopping panoply of butterflies in summer like the dark green fritillary and the silver-spotted skipper, and of course the blues, the Adonis blue, the chalkhill blue, and the common blue, all closely-related variations on a theme of brilliance. Even the birdlife of the chalk landscapes is exceptional, from stone curlews to skylarks: there are 14,000 pairs of skylarks on Salisbury Plain – even today – and in spring they pour down a shower of song which seems as much a part of the air as the wind.

But the rivers of the chalk are what I love best. The chalk streams, as anglers have named them, one word instead of two, are the most beautiful rivers anywhere on the planet. There are about 60 of them, from small rivulets to the queen of them all, the River Test in Hampshire, and they are characterised by the clearest and purest water in the natural environment, often referred to as "gin-clear". (The chalk filters it, and water companies are desperate to get their hands on it).

The chalk streams are immediately arresting. Their flow is stately, never sluggish, never torrential (the Test is like the Loire in miniature) and they are filled with a profusion of fish, of aquatic wild flowers like the ranunculus, the white water buttercup, and of aquatic insects of which the most magnificent is the mayfly, which is emerging just about now. Over the next month there will be clouds of mayflies over the chalk streams, the males dancing to attract females in one of Britain's most stunning wildlife spectacles, before mating and falling back to the water surface where trout will greedily gobble them.

Even a glance at a chalk stream lifts my spirits, and every time I catch sight of one I feel like offering up a prayer in praise of calcium carbonate. To some people it might be merely the stuff they use to powder the lines on tennis courts, but it also gives us the gentleness of the English landscape, the pyramidal orchid, the Adonis blue, and rivers which flow straight into your heart. And when I unfold the 10-mile map and look at the great green splash on it, that's what I see.

Lovely lilacs

Sorry to be banging on about blossom, after having written about the stuff for the last two weeks, but I have to put in a word for lilac. This is a cultivated shrub rather than a part of the natural world now, of course, so really lilac comment belongs in a gardening column. But lilac this year has never seemed so spectacular. Is it the freezing winter and the late spring? I've no idea. Yet the branches of the lilac in our garden are quite literally bending under the weight of their blossoms, with that distinctive woody scent (with a hint of a sour edge to it) perfuming the air. Something else to give thanks for.

For further reading

'Wild Flowers of Chalk and Limestone' by JE Lousley (Collins New Naturalists series, no.16)

Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Bookkeeper / Office Co-ordinator

£9 per hour: Recruitment Genius: This role is based within a small family run ...

Recruitment Genius: Designer - Print & Digital

£28000 - £32000 per annum: Recruitment Genius: This Design and marketing agenc...

Recruitment Genius: Quantity Surveyor

£46000 per annum: Recruitment Genius: This property investment firm are lookin...

Recruitment Genius: Telesales / Telemarketing Executive - OTE £30k / £35k plus

£18000 - £35000 per annum: Recruitment Genius: This company specialises provid...

Day In a Page

War with Isis: Fears that the looming battle for Mosul will unleash 'a million refugees'

The battle for Mosul will unleash 'a million refugees'

Aid agencies prepare for vast exodus following planned Iraqi offensive against the Isis-held city, reports Patrick Cockburn
Yvette Cooper: We can't lose the election. There's too much on the line

Yvette Cooper: We can't lose the election. There's too much on the line

The shadow Home Secretary on fighting radical Islam, protecting children, and why anyone in Labour who's thinking beyond May must 'sort themselves out'
A bad week for the Greens: Leader Natalie Bennett's 'car crash' radio interview is followed by Brighton council's failure to set a budget due to infighting

It's not easy being Green

After a bad week in which its leader had a public meltdown and its only city council couldn't agree on a budget vote, what next for the alternative party? It's over to Caroline Lucas to find out
Gorillas nearly missed: BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter

Gorillas nearly missed

BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter
Downton Abbey effect sees impoverished Italian nobles inspired to open their doors to paying guests for up to €650 a night

The Downton Abbey effect

Impoverished Italian nobles are opening their doors to paying guests, inspired by the TV drama
China's wild panda numbers have increased by 17% since 2003, new census reveals

China's wild panda numbers on the up

New census reveals 17% since 2003
Barbara Woodward: Britain's first female ambassador to China intends to forge strong links with the growing economic superpower

Our woman in Beijing builds a new relationship

Britain's first female ambassador to China intends to forge strong links with growing economic power
Courage is rare. True humility is even rarer. But the only British soldier to be awarded the Victoria Cross in Afghanistan has both

Courage is rare. True humility is even rarer

Beware of imitations, but the words of the soldier awarded the Victoria Cross were the real thing, says DJ Taylor
Alexander McQueen: The catwalk was a stage for the designer's astonishing and troubling vision

Alexander McQueen's astonishing vision

Ahead of a major retrospective, Alexander Fury talks to the collaborators who helped create the late designer's notorious spectacle
New BBC series savours half a century of food in Britain, from Vesta curries to nouvelle cuisine

Dinner through the decades

A new BBC series challenged Brandon Robshaw and his family to eat their way from the 1950s to the 1990s
Philippa Perry interview: The psychotherapist on McDonald's, fancy specs and meeting Grayson Perry on an evening course

Philippa Perry interview

The psychotherapist on McDonald's, fancy specs and meeting Grayson Perry on an evening course
Bill Granger recipes: Our chef recreates the exoticism of the Indonesian stir-fry

Bill Granger's Indonesian stir-fry recipes

Our chef was inspired by the south-east Asian cuisine he encountered as a teenager
Chelsea vs Tottenham: Harry Kane was at Wembley to see Spurs beat the Blues and win the Capital One Cup - now he's their great hope

Harry Kane interview

The striker was at Wembley to see Spurs beat the Blues and win the Capital One Cup - now he's their great hope
The Last Word: For the good of the game: why on earth don’t we leave Fifa?

Michael Calvin's Last Word

For the good of the game: why on earth don’t we leave Fifa?
HIV pill: Scientists hail discovery of 'game-changer' that cuts the risk of infection among gay men by 86%

Scientists hail daily pill that protects against HIV infection

Breakthrough in battle against global scourge – but will the NHS pay for it?