The North of Spain is home to some of the most impressive Roman remains in the world. From rich villas and roads trodden by generations of centurions to thermal baths and fortifications.

Now, a TerraDat team has helped archaeologists to uncover the largest Roman mosaic in Asturias. At almost 11m long by 4m wide, the mosaic’s detailed pieces show classical patterns and knots.

Team leader and Senior Geologist/Geophysicist Dr Javier Olona said:

“The ground penetrating radar (GPR) gave a clear sign of a buried pavement at the site at the town of La Estaca so the archaeologists knew where to concentrate their digging.

“They uncovered a large and splendid Roman mosaic created in the Third Century AD, and at almost 11m by 4m the largest mosaic discovered in Asturias.

“This is a find of significant archaeological importance which excited the archaeologists and attracted the attention of other scientists in the area.”

Mosaics were used to decorate the floors of Roman public buildings and high-status homes like villas.

They were created from thousands of small coloured stones or gems, called tesserae, stuck to the ground with a form of cement.
They were popular because they reflected the light around a room, were easy to clean, and fitted well with the Roman hypocaust system of under-floor heating.

The earliest mosaics from the late second and early first centuries BC were found in Pompeii.
The La Estaca mosaic features typical Roman artwork such as the Greek meander, the guilloche, and the Solomon knot.

How important are Roman archaeological finds in Asturias?

This region in the North West of Spain is home to some of the most important Roman archaeology in the world.
It was the scene of bloody resistance to the Roman invasion, something which prompted Augustus, probably Rome’s most successful emperor, to personally lead 80,000 soldiers into battle in 25BC.
The local Celtic tribe, the Astures, has used their local knowledge of the mountainous terrain to wage a lengthy guerilla war against the invaders.
Augustus led his soldiers towards the town of Carabanzo in Lena and a bloody battle was fought at Via Carisa.
While there was a Roman win, it came at huge cost in lost life and injury, and although it was part of the Roman empire the area was never fully conquered.


The Roman occupation left a rich archaeological legacy in Asturias.
Of particular note are the Roman village at Veranes, the rich roman archaeology at Campa Torres, thermal baths at Camp Valdés, the most important ruins found in the North of Spain, and the Roman wall at Gijón also built in the Third Century.
All of them help to build a detailed picture of how Romans lived, loved, and worked and how they interacted with the local tribe.
The Romans established urban, industrial, and rural areas linked by a substantial network of new roads.
Gold mines were sunk in the west of Asturias after large scale deposits were found there, making Asturias an important area for Rome.
As a result, trade with and from the region increased markedly.

How did TerraDat help find the mosaic?

The geophysics team at La Estaca used a combination of magnetic and ground-penetrating radar (GPR) techniques to survey the village.
A detailed survey grid was marked out, covering the area of interest. The magnetic and GPR instruments were then carried or pushed across the grid along 0.5m or 1m spaced survey profiles.
Magnetic survey instruments map distortions in the Earth’s magnetic field associated with the presence of buried ferrous (iron) objects and disturbed ground. Depending on the magnetic responses, it is possible to identify remnant archaeological features such as building locations, property boundaries, kilns, ditched and pits, as well as disturbed ground and buried objects.

A GPR survey involves pushing or pulling radar antennas along the ground’s surface. A pulsed electromagnetic(radio) wave is transmitted into the ground. The pulse bounces off buried layers or objects and the retuning signal is detected and recorded by a receiver in the same instrument. Different frequencies of electromagnetic pulse can penetrate to different depths and give different resolutions of buried features. The GPS instrument builds up a 2D cross-section of the shallow sub-surface. These profiles can then be merged into a 3D block, showing how the response varies at different depths across the survey area. These maps can resolve building outlines, areas of disturbed ground and buried surfaces, such as mosaics, at different depths.
During the project, the TerraDat team also investigated the cathedral in nearby Oviedo as archaeologists looked for evidence of structures such as ancient churches.

How could these TerraDat techniques help you?

Many planning authorities will insist on an archaeological survey before work begins at any site where there could be historical remains.
Our magnetic and GPR surveys will help you discover whether you have archaeology which needs to be investigated or whether you can proceed with your building work.
The same techniques are also useful for finding out whether you have metal deposits at your site.

Call us on +44 (0) 2920 700127 for more information.