Peter Brown investigates how wind-blown sand threatened medieval coastal communities
Research in brief
- Communities have a long history of finding ways to build resilience to natural hazards, such as wind-blown sand. Modern preparedness and adaptation planning needs to acknowledge this established wealth of community-based knowledge and experience.
- The greatest challenges to communities from natural hazards arise when new, unexpected or very sudden hazards occur.
- Today we need to improve the ways that local civic intelligence and scientific expertise can be harnessed together to address changing environmental hazards.
When we think about natural hazards facing the UK, wind-blown sand is probably far from the top of the list. In truth, it is not the hazard that poses the greatest risk today, but in the past wind-blown sand was responsible for the devastation of many British coastal communities. Archaeology can highlight the endurance over time of towns, villages, isolated settlements, and individual buildings.
With the additional evidence provided by historical documents, the medieval period offers a particularly rich dataset from which to illustrate them hardships and abandonments precipitated by wind-blown sand.
Medieval village abandoned in Aberdeenshire
An example comes from the Aberdeenshire coast where sand caused the village of Forvie to be completely abandoned in the year 1413. A storm from the south coincided with an extremely low tide resulting in more sand than usual being exposed to the storm winds, which deposited vast quantities across the village and its surrounding agricultural lands.
Past investigations by researchers from Aberdeen University since the 1950s uncovered the remains of the parish church dedicated to Saint Adamnan as well as evidence for medieval cultivation which is visible on aerial photographs.
The surviving community must have been forced to leave almost immediately with their crops ruined and homes buried. By the end of the 15th century a new church of Saint Adamnan had been established six kilometres to the north at Leask, perhaps where many of the refugees moved following the disaster.
Prior to the rapid rise in sand levels at Forvie, sand may have been making more gradual inroads as the archaeological evidence demonstrates animal manure may have been applied to the soil just before Forvie’s abandonment.
This was most likely a strategy to remedy the reduced fertility of the soil caused by the movement of sand on to areas of arable cultivation. By this point, however, it was probably too late. Mitigation strategies to deal with the effect of strong winds on large areas of sand dune are limited.
Sands can be stabilised by the establishment and maintenance of species such as pine and marram grass which hold sand together, reducing exposure to high winds and preventing movement. But to do this effectively requires time and considerable resources.
While the importance of vegetation cover may have been appreciated throughout the Middle Ages, evidence for its management only appears in the Elizabethan period when laws were passed enforcing the protection of marram grass, which was commonly used as thatch, around Newborough, Anglesey.
Similar laws were passed throughout the post-medieval period in Denmark and Scotland. Therefore, it seems a failure to appreciate the risk posed by the sands, or to organise the community to enact preventive measures, must have occurred at Forvie.
The loss of Meols, Merseyside
Another settlement which was lost following sand encroachment was Meols, Merseyside, where a thriving fishing and trading community existed up until the close of the 15th century. Discoveries of coins, personal accessories and other artefacts over the last two hundred years allow a particularly in-depth picture of this event to be reconstructed.
A drop in the quantity of coins from the 14th century suggests environmental conditions could have become increasingly problematic, but material remains continue to demonstrate occupation until the end of the 15th century. At this point a community appeared two kilometres to the south at a location called Great Meols, and a thick layer of sand entombed the medieval remains of the original settlement.
Analysis of historical maps has demonstrated that the new settlement must have developed in response to the loss of Meols, with formerly marginal fields reorganised to form the heart of a new settlement. This must have been a time of great upheaval and Meols was not a case in isolation, with a number of other towns and villages, known from historical documents, disappearing at a similar time along the Merseyside coast.
This may have been a result of increased storminess caused by changes in climate, but whatever the reason, the surviving inhabitants of these settlements had no choice but to relocate.
Middens: Mitigating wind-blown sand hazards
Less major sand encroachments could be mitigated or prevented using a variety of methods. Sites from viking-age Orkney provide evidence of the use of middens (mounds of refuse) as a means of stabilising wind-blown sand by spreading the midden material over the surface.
At Evertaft, Orkney, several layers of midden were interspersed with blown sand, probably representing a hazard which intermittently plagued the community in severe weather rather than one which precipitated absolute abandonment.
A parallel for this practice can be found in Carmarthen Bay, where midden material was similarly redeposited on top of wind-blown sand. Middens were also used to make the Mound of Snusgar, Orkney, habitable and improve the productivity of the surrounding agricultural lands.
However, the heightening effect of the midden material may have had negative side effects, increasing the quantity of wind-blown sand trapped by the mound and eventually forcing its abandonment.
Thus using middens as a protective barrier in a suitable location can halt the progress of sand, forming a sand bank. This can provide additional benefits such as protection from coastal flooding, but when the sand grows to the height of the fence, a taller barrier, or a new one further inland, is required to provide further protection. Barriers are not preventive measures – they can only buy time.
While no archaeological examples are known from medieval Britain, a number have been excavated from dunes in the Netherlands, although at those sites the barriers had been overcome by the movement of sand, and the fields they protected had become inundated.
Working with the environment
Modifications to the natural environment also provided protection from wind-blown sand for some medieval communities. At Merthyr Mawr, South Wales, documentary evidence records the diverting of the River Ogmore to prevent the movement of sand in the 16th century.
The survival of Merthyr Mawr compared with other nearby medieval towns such as Kenfig and Pennard, which were both completely inundated with sand and subsequently abandoned, suggests that these measures were ultimately successful.
Similarly, when the oratory of Saint Piran at Perranzabuloe, Cornwall, was threatened by encroaching wind-blown sand around 1150, a new church was built less than 500 metres away, but with a stream separating the new church from the old site.
This seems to have prevented the sand moving further inland because when the stream was diverted in the 18th century for mining purposes, the sand once again began to move inland and the church had to be abandoned soon after, in 1804.
Christians loved relics and those of Saint Piran were housed within the church. They were believed to emanate divine magical power which could offer healing, good fortune, and protection. As a result the relics attracted a steady stream of pilgrims up until the reformation.
The dunes covering the original oratory held such a spiritual connection to St Piran that they became a popular burial place with sun-bleached bones visibly protruding from the sands. It is therefore very likely that the power of the saint was believed to protect the new church from the danger posed by the sands.
For many communities in England and Scotland during the Middle Ages sand inundation was a calamity for which they were ill-prepared. The worst case scenario forced total abandonment and relocation; a failure to address the underlying problem, the stability of the sand dunes, ultimately made this unavoidable.
While they may have been victims of a quickly worsening climate, medieval reliance on spiritual protection rather than material intervention made them vulnerable to the drastic environmental changes brought on by severe weather events.
Wind-blown sand hazards today
Since the 19th century, and especially since the First World War, the stabilisation and maintenance of sand dunes through the establishment and protection of plant species has become a priority and as a result, the threat posed by wind-blown sand to British communities has largely been eliminated.
Despite this, problems are not entirely a thing of the past, East Lindsey, Lincolnshire, was inundated by sand last spring, causing problems particularly affecting infrastructure.
Wind-blown sand is also a problem in many other parts of the world, such as in Western Australia, on the west coast of the US, as well as in desert countries where there are numerous examples. Wind-blown sand can also cause dust storms, as has recently been the case in Beijing and neighbouring regions.
With the potential for devastation demonstrated by medieval examples and the increased storminess of recent winters, the maintenance of protective vegetation and active monitoring of sand dune environments must remain a priority.