TODAY they appear as weathered stone slabs, worn by time and bleached grey by the Scottish soil in which they were found.

But now cutting-edge research carried out on Roman carved reliefs found at the Antonine Wall has revealed they were once painted in vibrant colours - and were designed to send out a message to the ancient tribes who called the region home.

Dr Louisa Campbell, of Glasgow University’s archaeology department, spent eight months painstakingly analysing trace elements in the sandstone slabs using X-Rays and lasers to reveal how they would have looked to Roman eyes.

For the first time she was able to establish a vivid palette had been applied, from ochre to give the figures life-like skin tones, to a lead-based red on the cloaks of the soldiers.

READ MORE: The Romans 'forgotten war' against Scotland

But the months of work also revealed a grisly secret, with the carvings of captive and defeated natives splashed with deep red 'blood'.

The gory imagery was even extended to the beak of a Roman Eagle depicted, as it apparently feasted on the bodies of slain foes who dared to challenge Rome's authority.

HeraldScotland:

The Summerston, found near Bearsden

The Antonine Wall, a turf and timber mound stretching between the Firth of Clyde and the Firth of Forth, was erected on the orders of the Emperor Antoninus Pius in 142 AD by the legions stationed in the area.

The soldiers left behind decorative markers after completing their sections, with around 20 surviving to this day. These slabs formed the basis of Dr Campbell's research.

She said the painted stones would have been a form of propaganda by the occuplying Romans, letting the Caledonian tribes know who was in charge and the fate of those who would fight against the legions.

The Academic said: "The public today sees the slabs in bland greys, but to the people of the time they would have been brightly coloured in yellows and different shades of red.

"On one hand they were for the soldiers to show their dedication to the Emperor, as they say the work was carried out in his name. But for the local people they would have served as reminders of the power of Rome.

"They were part of the act of subjugation and the projection of power. And they were a warning not to go up against Rome."

The carvings, which also marked distances along the wall, bear inscriptions in Latin dedicating the wall to the Emperor. 

Most of the examples available were discovered between the 17th and 19th centuries, and are on display at the University’s Hunterian Museum.

HeraldScotland:

Little remains of the Antonine Wall today

One, the Summerston, was found on a farm near Bearsden at what may have been the base of the Second Legion.

The slab reads: “For the emperor Caesar Titus Aelius Hadrianus Antoninus Augustus Pius, Father of his Country, the Second Augustan Legion (built this) over a distance of 3666 ½ paces.”

One panel on the left depicts a winged Victory, which would have been painted a golden yellow, holding a laurel wreath preparing to crown a cavalryman who rides down two bearded and bound captives.

On the right panel an eagle appears to perch on the back of a Capricorn, the emblem of the Second Legion, above another captive.

READ MORE: The brutal weapons that defended the Antonine Wall 

Dr Campbell said: "On the figures of the natives there splashes of blood on their cheeks, chest and thighs. On another slab there's a decapitated head which is dripping bright red blood.

"These people are fresh from a battle with Rome, and these wounds are the remains of that battle. That's a very stark message for anyone who would have seen them when they were freshly coloured."

HeraldScotland:

The Bridgeness Stone, found near Bo'Ness. Pic c/o National Museum of Scotland

The research, part funded by Historic Environment Scotland (HES), was carried out using X-Ray fluorescence and Raman spectroscopy to analyse elemental and mineral composition of the stones.

Dr Campbell said that the technique could now be applied to other artefacts in Scotland, such as Pictish, Christian or Viking relics.

She added: "This was a proof of concept project and we now know the technique works, even with material taken from the acidic soil of Scotland.

"Pictish stones which have only been exposed to the weather should, in theory, be easier to work with. There are many ways to apply this research."  

READ MORE: How the Romans of Bearsden lived 2,000 years ago

The next step will be to create digital reconstructions of the slabs as they would have appeared when new, while a bid is being made to have one fully reconstructed.

HeraldScotland:

A reconstruction of a battle between the Legions and Caledonians

Patricia Weeks, Antonine Wall Co-ordinator at HES, said: “We are delighted to have been able to fund Dr Campbell’s work and to see these exciting results emerge.

"Knowing how colour was used by the Romans to tell stories and create impact is a huge leap forward in understanding these sculptures.

“The information will now be used as part of our partnership ‘Rediscovering the Antonine Wall’ Heritage Lottery Fund bid to propose a recreated distance slab in full colour.

"We will also work on innovative digital methods of recreating the stones in colour that can be used for interpretation both out on the original find sites, and in the galleries at the Hunterian Museum.”