The sea is at war with the Isle of Wight. Sarah Shuckburgh learns of efforts to repel the
enemy without.

Jagged slabs of tarmac perch like giant stairs above a jumble of rock and clay, a dramatic cascade lured by the waves far below. The landslip is strewn with forlorn remnants of domestic life – a shoe, a carpet, patterned paper peeling from a sitting room wall, a shattered window with ragged curtains flapping in the wind. Butterflies flutter over the debris. A derelict Tandoori restaurant perches on the cliff edge – waiting to be toppled. The beautiful steep-sided valley of Blackgang Chine, once a smugglers’ lair, is sliding inexorably towards the sea.

I am on a 6th form geography trip to the crumbling south coast of the Isle of Wight. The teacher, Mr Crundwell, is such a fan of coastal erosion that he studied academic pamphlets on his honeymoon. Forget the island’s theme parks and tourist attractions, its music festivals, thatched cottages and chic marinas – and there’s no time today to admire the world-famous fossils of 15 species of dinosaur that once roamed this heritage coast. We are lured by the destructive, unstoppable power of nature, the relentless force of wind and sea. Our talk is of ferocious fetch and long shore drift, chalky chines and spines, coastal stacks and slacks, groynes and gabions, corrasion and corrosion, and two rivers called Yar.

Mr Crundwell told the girls they’d need passports, and he chuckles with delight when he finds that several have brought them. We certainly feel as if we are travelling abroad. The ferry chugs slowly from Portsmouth harbour, passing the gleaming spinnaker tower and then Lord Palmerston’s follies – defensive forts in mid-Solent, never used in war, and now home to a hotel.

At Ryde, a minibus takes us across the island, along winding lanes edged with wild flowers, through copses and over undulating pastures - a patchwork quilt of small fields with old-fashioned hedgerows. We pass road-signs warning of badgers, toads and red squirrels. Mr Crundwell knows better than to ask the pupils to look at the view – with headphones firmly plugged in, they are flicking through magazines. We disembark near the western tip of the isle, at Freshwater Bay, a now dry valley where the first river Yar met the sea before it turned round and flowed north. A light drizzle is falling. The local downs are named after Tennyson, who declared that the air here was worth sixpence a pint, but today it’s bleak and biting. Beyond the headland, the sea churns grey and choppy around the chalk needles. But Mr Crundwell’s enthusiasm is infectious, and on soggy, fluttering worksheets, the girls are soon recording stacks, recurved seawalls and wooden groynes.

“Coastal policy, ladies?” he quizzes. “Begins with H. Yes, ‘Hold the Line’.”

Our next stop is Compton Bay, where cliffs of soft sandrock and impermeable galt clay have collapsed in huge, untidy terraces. Stretches of new tarmac replace road recently engulfed by landslides. We clamber down to the beach to admire the fantastic fetch of the sea and the higgledy-piggledy shore.

“Rotational slumping, ladies,” shouts Mr C above the crashing surf. “What sort of coastal management? I’ll give you a hint: not many people come here. Begins with D. Yes, ‘Do Nothing’.”

The island’s heyday came during the nineteenth century, when fashionable Victorian society followed their Queen across the Solent, building seaside esplanades and villas. Other less elegant buildings date from the 1950s and 60s, when bucket-and-spade holidays became popular among ordinary folk. We pass pebbledash bungalows with ornamental stonework, and clusters of once gaily-painted holiday huts. Stunted wind-bent trees lean away from the prevailing wind. Above, steel-grey cloud cloaks the downs.

“What sort of rainfall, ladies?” enquires Mr C cheerfully. “Begins with O. Yes, ‘orographic’.”

We drive through the undercliff, a lush, sloping jungle caused by a landslip 10,000 years ago. Between Blackgang and Bonchurch, the coastal collapse has formed a romantic mix of tangled woodland and grey precipices, dotted with houses unwisely built on the shifting ground. At Ventnor, we zigzag down the cliff, past charming Victorian villas and palm trees, to the Esplanade, where we tuck into locally caught crab and lobster at the Spyglass Inn. After lunch it stops raining for ten minutes, and we walk along the Esplanade to buy cornets from Minghella’s (father of Anthony, the film director).

“There’s a fantastic coastal museum in Ventnor,” confides Mr C. “The best in the world. That’s where I got the leaflets to take on my honeymoon.”

Fuelled by crab and ice cream, we feel ready for more erosion controls, which is lucky, because there are plenty at Monks Bay, designed, with no expense spared, to protect grand cliff-top residences. The girls scribble on their damp worksheets - off-shore breakwaters, wire cages packed with boulders, Norwegian granite rock-armour and a beach renourished with dumped gravel.

There’s no time to stop in Shanklin’s picturesque town centre, with its thatch and tempting tea shops. We have eyes only for the vertical sandrock cliff-faces, which are interestingly netted, shuttered and drained.

At Sandown a few hardy holidaymakers are digging a sandcastle in the drizzle. The tide is racing in, and it looks fun, but Mr Crundwell won’t allow us even this vicarious enjoyment. He sets off along the beach at a brisk pace and we stumble after him.

“Who is to blame for the worrying erosion at the other end of Sandown bay?” he shouts over his shoulder. “Begins with T. Yes, ‘tourists’.”

Tourism spells money, and while the coastal managers at Sandown do all they can to preserve this lovely sweep of fine sand for castle-builders, they are inadvertently adding to the collapse of the London-clay cliffs further along the beach.

Our last stop is Bembridge harbour, where the second river Yar meets the sea. Here long shore drift has resulted in an interesting sandbar. Unluckily, it’s high tide, and we have to imagine salt marshes and spit beneath the red and yellow buoys bobbing on the water.

Rain drips from our eyebrows and trickles down the napes of our necks, as Mr C explains that dunes grow as blown sand, pale yellow and dry, is stabilised by salt-tolerant succulents with shallow roots. He looks in vain for sea twitch to illustrate his point. Giant tyre tracks lead ominously into the lapping waves. Nearby, a bin overflows with holidaymakers’ rubbish. Mr C looks grim.

“Humans! Digging gravel, dropping litter - threatening what, ladies? Begins with B. Yes, ‘biodiversity’.”

Mr C perks up when he spots deeper-rooted, moisture-retaining marram grass, growing on the embryo dunes. We crouch in a sheltered slack, where other plants have managed to put down roots and the sand is grey with decayed vegetation.

As the rain grows heavier, we run through puddles to a nearby pub and order mugs of steaming chocolate. Paintings by a local artist depict both spit and salt marshes at low tide, so Mr C makes the most of these unexpected visual aids for a final burst of enthusiastic lecturing.

“Tragic lack of sea twitch, though,” he mutters, as we drive back to Ryde. Then, brightening, he shouts, “Got your passports, ladies?”

The girls aren’t listening. They have turned on their ipods again. But I have decided to take up geography A level.

First published by the Telegraph
©SarahShuckburgh