By Dr Chloe Duckworth
In November 2016, nine archaeologists fled the UK to spend two weeks in the occasionally challenging, but always stunningly beautiful landscape of Madinat al-Zahra in the foothills of the Sierra Morena mountains, near Cordoba, where we were joined by a brilliant and enthusiastic team of local students from the University of Cordoba.
Our aim? To understand the urban layout of the site, using state-of-the-art, non-invasive techniques (of which more below), and to identify the location of high temperature workshops which served the palace and city.
The site, which consists of a palace and an accompanying city (madina), was built in the 10th century CE, by Abd al-Rahman III as a declaration of his power. He was the descendant of the Umayyads, the dynasty which had once ruled over the entire Muslim world, before being overthrown by the Abbasids in 750 CE. This turn of events caused the last surviving heir of the dynasty, Abd al-Rahman I, to flee to the Iberian Peninsula and set up independent rule in this far western outpost of the Islamic Empire.
But it was not until the Abbasids themselves were threatened, now by a new dynasty (the Egyptian Fatimids) that the leader of al-Andalus (in 928 CE) declared himself to be the rightful caliph, and heir to the Islamic world. As part of this declaration, he constructed a new palace and city. These are the origins of Madinat al-Zahra, ‘the shining city’.
A Buried City
Unlike the majority of cities built in the Islamic world at this time, the site was short-lived, with turmoil following the death of Abd al-Rahman III finally leading to its destruction and abandonment in the first decades of the 11th century. The palace was excavated in the early twentieth century, but almost none of the madina has been touched, preserving in tact its urban layout and revealing much about the intentions of those who constructed it. Today, it is protected land, grazed by a large herd of cows, and occasionally visited by greyhounds on a hare-hunt.
The exceptional nature of the remains means that any archaeological intervention has to be sensitive to their continued preservation. Regardless of whether such a site were ever to be excavated, much can be learnt about it with the use of non-invasive survey techniques, which allow us to ‘see’ beneath the ground, as well as plotting the topography of the site and the chemistry of the soil. We have begun to map the urban layout as it is preserved today; and have started to find evidence which could relate to the locations of the workshops that produced the fabulous architecture or luxury goods of the palace, and the equipment required by the extensive military housed at the site.
How to See without Digging
The main technique we used was magnetometry. This technique measures, and allows us to map, patterns of magnetism in the soil. Buried features will affect the patterns, which is how the technique allows us to identify buried walls, ditches, and – importantly for us -areas which were subjected to high temperature in the past, including ovens and furnaces. We set up grids, spatially rooted to cardinal points by GPS, and the magnetometer operators (carefully kitted out in entirely non-magnetic clothing) walked systematically across them, recording the changes in the signal. These records are then downloaded and a computer is used to map them and link them to the results from previous days and other known information about the site.
Chemical mapping was done by the use of handheld pXRF – this technique fires X-rays at whatever is immediately in front of it, and by reading the returned signals is able to identify what elements are present. The use of handheld pXRF in this way was originally pioneered by Dr Roger Doonan of the University of Sheffield, and is championed at Madinat al-Zahra by our own Dr Derek Pitman. The technique has traditionally been used to read the chemistry of objects, particularly metals. The genius of using it to find the location of production sites is that it can be placed directly onto the ground in order to identify areas of the soil which were polluted by metals in the past. High concentrations of metals not only suggest that some industrial activity may have taken place in a particular location; they also help to ascertain what kind of activity it might have been.
Chemical readings were taken in combination with magnetic susceptibility, which along with the XRF looks like something out of the original Star Trek (as demonstrated below by yours truly, in a fetching mac). Magnetic susceptibility is particularly useful for identifying where there may be a broader spread of burnt material, rather than an intensive concentration such as those picked up by the magnetometer. Finally, a topographic survey was conducted by Chris Caswell, in order to map the present ground surface, which is also related to the location and identify of buried features. These are only a selection of the arsenal of non-invasive survey techniques now available to the archaeologist. They key in any work is to tailor the choice of techniques to the site in question, as well as – somewhat unavoidably – the budget available!
Oy! You Mentioned Game of Thrones..?
We had a stupendous season, and the results are already being prepared for publication (watch this space). On a free Sunday, I was able to visit one of the quarry sites from which materials had been taken to construct the palaces: it was a beautiful place, with the marks of quarrying still clearly visible in the rock.
But okay, since you ask: non-archaeological highlights included learning that while we were there, the area was full of Game of Thrones actors, who were filming at the nearby site of Almodovar del Rio, a stunning restored castle seductively visible from Madinat al-Zahra. We weren’t quite close enough to offer any spoilers, but where would be the fun in that?