“ISN’T it great that we’re up here talking about art?” said a lady sucking on a pear while sitting on the edge of a hush at the top of Teesdale.

From her vantage point, the breathtaking - if barren - majesty of the dale was laid out before her, a warm but blustery breeze blew off Mickle Fell in the distance into her face, and she sat amid little pinpricks of white flowers which spangled the soft grass in the way distant stars twinkle in the night sky.

The breeze was also tugging at what she had come to see: Hush, one of the country’s biggest ever outdoor artworks.

It is five kilometres of recyclable saffron yellow sheets strung out by artist Steve Messam on 20 or so washing lines across a 20 metre deep, V-shaped gouge in the countryside.

For an artwork entitled Hush, it makes a hell of a noise as you walked through it. It creates an exhilarating flapping, like being inside the rigging of a ship at sea – there are sails in the dales.

The sheets are rigged across Bales Hush which runs 400 metres (or 1,300ft) up the side of the dale.

The hush was made by leadminers, probably in the 18th Century. The miners would build a reservoir with turf walls at the top of the dale and release the water which would down rush at full pelt. Older historians believe the water scoured away the vegetation to expose a seam of lead ore which could then be dug out. Newer research reckons that the leadminers had already been opencasting the seam with picks and shovels, and they used the rush of water to wash away all their deads and debris, leaving the seam clean so they could continue their handworking.

Either way, hushes have left scores of scars on the sides of Teesdale. Bales Hush is believed to be one of the last where leadmining continued into the 1860s, and it is amazing to pick your way up it on a summer’s day and think of the men who filled the dale with the chink of their axes in the teeth of a winter’s gale 250 years ago.

But what relevance does any of this heritage have to today’s sea of flapping sails? Amazingly, there’s 4G at the top of the hush, enabling me to post pictures on Twitter which were greeted with some cynicism. “Good drying weather?” asked one person; “a Buddhist’s washing line”, said another.

Others asked why the sheets were yellow when the dale is fifty shades of green, the water is peaty brown and the lead was shiny silver?

“Doesn’t the billowing of the sheets reflect the movement of the water?” asked the pear-sucking lady’s husband, in his shorts and walking boots, having come out from Darlington. “It’s much better than it being static.”

I agreed, but the billowing was bothering me. The wind was tearing in from the south-west – literally tearing, as bits of the sheets were being ripped off (let’s hope they compost quickly). It was such a regular prevailing wind that even the stinging nettles grow bent over, and it was causing all the sheets to travel to the western end of their washing lines and drape themselves on the daleside.

The sheets were blowing up the hill whereas the water, of course, would have been dashing down the hush. “The movement,” I said, “is in completely the wrong direction.”

So then, to the delight of the pear-sucking lady, we sat amid the tiny white flowers of the heath bedstraw and discussed whether this was good art. Does art have to be an accurate representation of what it depicts or is it a unique idea that gets you thinking and engaging?

As we concluded that this was “striking art” or “intriguing art”, a group of young boys deep in the hush below discovered the carcase of a sheep.

“Don’t touch it, don’t touch it,” shouted their father, but it was too late. The boys had lifted the rotten ribcage up in triumph. “Can we cut the horn off?” asked one boy. “Yeah, let’s saw the horn off,” said another.

This is the real beauty of this artwork. On Sunday, a steady stream of people snaked their way up the countryside from the Bowlees Visitor Centre to inspect and photograph it - one chap I spoke to had lived more than 60 years in Middleton-in-Teesdale four miles away and had never visited Bales Hush before.

It is intriguing enough to draw people out of their homes to interact with it, to clamber through their heritage and to explore a corner of the countryside that is usually forbidden to them. Hush is worth shouting about.

It is in situ until August 4. It is a fairly demanding 1.8-mile, one-hour long, uphill walk from Bowlees Visitor Centre, although there is a small car park next to the hush. At weekends, a minibus takes visitors from the centre to the hush – but you still have a short, steep walk to get among the sails, and for the very best views, you need to climb above the hush. We rode up in the minibus and the walk back down completed a memorable day out.