It was an ecological disaster which devastated one of the worlds's rarest landscapes, but the fire which ravaged the North York Moors last year has had an unexpected twist. Nick Morrison reports.

AT first, it seemed to be a largely abstract, although highly unusual, pattern. A series of diamond shapes surrounding a main feature resembling an hourglass, with a number of wavy lines to one side. It was only when the image was rotated to sit on its end that a light went on inside Neil Redfern's head.

The diamonds turned into fields, the hourglass into a house, with the additional line on one side representing a door. The triangles now at the top were mountains, the wavy lines perhaps the sea, or birds in the sky.

Only a theory, but if it is right, it transforms the way we view prehistoric rock art.

"It was almost as though we were looking at some kind of picture, somebody trying to draw their landscape," said Mr Redfern, inspector of ancient monuments for English Heritage.

"And if that's true, then this is something we have never seen before.

"When we first uncovered it, we hadn't turned it round and, although we knew it was amazing, we probably underestimated how significant it could be. It is absolutely fantastic."

But the 4,000-year-old carvings, on a stone only a metre in diameter, was only uncovered due to an ecological disaster.

It was in the middle of a hot September last year that fire broke out on Fylingdales Moor, above Ravenscar between Whitby and Scarborough on the North York Moors.

By the time the flames were brought under control four days later, about two-and-a-half square kilometres of heather moorland had been destroyed, the heat so intense that even the layer of peat underneath the heather had been burned away.

But as experts moved in to assess the extent of the catastrophe, it soon became clear that there was an unexpected bounty.

In burning away the vegetation, the fire exposed what lay underneath.

"There was so much material and a whole series of extraordinary features," said Mr Redfern.

"The aerial photographs were able to show us complete prehistoric field systems, stone banking that had fallen down and had never been seen before, potential prehistoric settlement enclosures. We got a lot more detail about settlement on the moor, which was pretty much a surprise to us, and while we knew there was rock art at Fylingdales, what we didn't know was just how much."

Starting from a base of 30 previously known monuments, the team uncovered 189 examples of rock art, among about 2,400 archaeological features.

Some of them are of comparatively recent origin, such as the ammunition shells and trenches from troop training during the Second World War, and the water system used to supply the alum works from the 17th to 19th Centuries.

Others are much older, evidence of the first known settlements on the Moors, some 4,500 years ago.

"The fire revealed a whole series of features from different periods, and a lot of them seem to be early prehistoric, and some of them are so subtle we could never have appreciated them without losing all the peat," said Graham Lee, archaeologist for the North York Moors National Park.

"The land is managed by controlled burning, but it was the intensity of the fire which caused so much damage, and stripped the peat off as well as the vegetation.

"This moor had been seen as quite special because of its relationship to the coast, This is the last surviving piece of coastal moorland, but its importance has now increased exponentially."

But the archaeologists had to work quickly. The longer the soil was exposed, the more it would be damaged, and the harder it would be to restore. And unless the vegetation returned soon, much of the archaeology would not survive.

As well as aerial photographs, experts and volunteers carried out a survey of the moor, before grass reseeding and heather transplantation work began.

In the first phase of a three year £55,000 project - funded by English Nature, English Heritage, the North York Moors National Park, landowners the Strickland Estate and the Court Leet, responsible for managing the moor - heather from neighbouring moorland was spread over the land, heather bales were used to block water channels, and grass seed was scattered across the bulk of the moor.

A second phase will extend over the remaining land, funded by a £200,000 grant from the Government's Department for Rural Affairs under its Countryside Stewardship Scheme.

"If we didn't do anything, the landscape would just blow away. It made the archaeological features very fragile and, every time people walked on them, it was displacing the stone and destroying the archaeology," said Mr Redfern.

But the restoration work means that all of these features, including the "map" stone, will be covered over by the grass and the heather - leaving it hidden from view once more.

"The stone had never been moved; it is still in its original context. It is part of the landscape, and we wanted to preserve it in situ," said Mr Redfern.

"There is also the potential for more stones like this on the moor, and where would you stop taking things away?"

But among all the 2,400 features uncovered, it is the stone that resembles a map which has excited most interest.

Whereas most known rock art carries a circular pattern, what is known as cup-and-ring marks, this features diamonds and triangles.

And where diamonds have been found carved on other rocks, in north-western Scotland and Ireland, these are usually in a symmetrical pattern.

"This is completely different. Is it a map, or is it graffiti? Is it a rite of passage, or is it a boundary marker? Is it a funeral marker? There are so many ideas and we don't really know," said Mr Redfern.

"The majority of cup-and-ring stones seem to be abstract, and I don't feel this is quite so abstract.

"Is it a mountain scene with a sky behind it? Is it somebody's house, and are we looking at fields within a larger enclosure?

"This stone has an ability to tell stories that capture the imagination.

"The beauty of rock art is, because we don't know what it is.

"Everyone can pitch in to think of what the story is.

"Rock art, to me, is one of the most amazing things our ancestors have given us.

"They have given us so many questions, and we are not necessarily coming up with the right answers."