Field Dispatch

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Monday, May 23, 2011

By Stephen Battle, WMF’s Program Specialist for African Architectural Heritage

Loropeni looms out of the bush, a mysterious, silent relic. There are no signs of habitation; no tilled fields, no houses, no cattle. A path winds through the bush and collides with the structure. Its walls are 6 metres high in places, the size of a double-storey house. Square in shape, each side is almost exactly 100 metres long. Its rigid geometry is startling, unexpected. Archaeologists have found no trace of an entrance, and there are no other openings in the wall; no windows, no embellishment at all. Small sections of wall have partially collapsed and it is now possible to scramble inside. But there is not much more to see; a few low-standing walls made of the same rust-red lateritic stone. Vegetation has claimed part of the enclosure. But the power of the place is not in what you see, but in what you feel. It has a silent, brooding presence. Local historians speculate that it has survived because of its importance in local religions. It is not hard to see why; the place resonates with spiritual power.

Carbon-14 analysis has dated construction of Loropeni to the eleventh century A.D. At that time the region was occupied by the Lohron and Koulanga peoples, whose wealth stemmed from control over the extraction and smelting of gold. Modern-day borders with Ghana and Ivory Coast are not far to the east and south, and the remains of similar structures can be found throughout the region. But none are as well preserved as Loropeni. Up to 80% of the original structure survives, and in this respect it is exceptional. Excavation suggests that is was last occupied in the eighteenth century. Archaeologists and historians can only speculate about its original use. There is no trace of domestic inhabitation, other than a few small enclosures, ruling out an urban function. The walls are massive, suggesting their purpose was primarily defensive, built to protect whatever precious commodities were stored inside; gold, and perhaps slaves?

Loropeni is a protected monument in Burkina Faso, and since 2009 it has been recognised as a World Heritage Site by UNESCO. It first came to the attention of WMF in 2008, when it was placed on the World Monuments Watch. Although it has survived into the twenty-first century remarkably intact, parts were in urgent need of preservation. Sections of wall had separated and were tilting alarmingly. In other places, large cracks endangered its structural integrity. Climbing trees had invaded the wall, spreading along the surface and burrowing into its core. Stones were missing and earth mortar was washed away. None of these problems were in themselves particularly complicated to solve. The main challenge lay in the remoteness of the site. In addition, the conservators were aware that they could do a ‘perfect’ job and still destroy its essence. The preservation exercise had to solve problems whilst taking extreme care to not overwhelm or obliterate its intangible character.

A preservation project commenced in early 2009, with funds from the Annenberg Foundation. Watch-listing raised the profile of the site in Burkina Faso and brought it to the attention of other donors. Additional funds for the project were secured from the Netherlands Embassy in Burkina Faso and the African World Heritage Fund, which is based in South Africa. The project was led by the Direction générale du patrimoine culturel du Burkina Faso (DGPC), with technical assistance from CRATerre-ENSAG, an NGO based at the University of Grenoble, France, which specializes in earth construction.

Other than minimum intervention, the most important principle in conservation is to repair like with like. In this case, the most critical aspect of the process was to identify the original earth used to make mortars and to match the mix ratios and ingredients of these mortars as closely as possible. If mortars are stronger than the original they tend to separate from the historic substrate and fail. If too soft, they quickly erode. In addition, the conservators were keen to match the original color and texture. During the research phase, earth was excavated from four different pits close to the original walls. Laboratory analysis revealed that the composition of each earth source was different; some had more clay, others larger sand particles. Using earth from each of these pits sample walls were built, matching the construction of the original walls. And these walls were then left for 7 months, through an extremely heavy rain season (1,088mm of rain fell in Loropeni that November) and a baking hot dry season. When the team returned it was immediately apparent which earth mixture had performed best. Some failed completely. Others were riven by deep channels. On the basis of these tests the team could specify the precise source and ratio of the materials to be used.

Preservation work commenced in 2010. Ten local masons, specialists in traditional earth construction, from a nearby village joined the team and were trained in conservation techniques. They will form the core of a permanent maintenance team. The conservation process was led by Mr. Barthélemy Kaboré, a conservator from the DGPC and Dr. Lassina Simporé, an archaeologist from the University of Ouagadougou. Technical direction was by Mr. David Gandreau, assisted by Mr. Grégoire Paccoud, both of CRATerre-ENSAG.

A number of interventions were undertaken. Where walls were tilting props were inserted. Holes in the wall were filled with original stones collected from the base of the walls. Cracks at the top of walls were filled and wall sections had separated from one another were stitched back together. Wall heads were repaired and covered with sacrificial plaster coats to repel rain. Mortar joints between the stones were filled and re-pointed. A large amount of vegetation was removed from the base of the walls. It was not possible to remove all the trees that had taken root in the wall; over the years they have become part of its structure: but these were severely cut back to retard their growth. In addition, drainage across the site was improved to prevent ponding and speed-shedding of rain-water.

WMF’s project at Loropeni was successfully completed in November 2010.

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