Mam Tor magnified COLIN MERRONY of the University of Sheffield describes how a new survey of the Mam Tor has shed a startling new light on the hillfort
T
he well-known hillfort of Mam Tor stands at the head of the Hope Valley, with Edale to the north and the valley of the Blackbrook, which runs down to the Goyt Valley, to the west. Excavations undertaken by the University of Manchester in the 1960s produced a radiocarbon date from the late Bronze Age. While there has been some limited archaeological work on Mam Tor in the years since the 1960s there has not been any detailed survey work. Mam Tor is known not only for its dramatic location and its huge enclosing ramparts, but also for the many hut platforms cut into the slopes within the hillfort. In the 1960s excavations, 10 of these features were investigated. The results showed that these were the sites for buildings, generally with a gully at the back of the platform and then evidence of shallow deposits
This QGIS image highlights areas which receive more light (e.g. flat terrain or ridges) and presents areas which receive less light, such as pits and ditches, as darker
Local relief model image where the overall shape of the hilltop is removed to allow the smaller changes, such as archaeological features, to stand out more clearly
which were interpreted by the excavators as suggesting sporadic or seasonal use of the site, rather than longterm permanent occupation. In the summer of 2020, a new survey was conducted by students from the Archaeology Department at the University of Sheffield. This survey was the basis for Poppy Forshaw-Perring’s dissertation for her MA in Landscape Archaeology. In addition to some geophysical survey the whole area of the hillfort was photographed from a drone by David Inglis. These photographs were taken at consistent height and spacing on a regular grid pattern. This ensured that each photograph overlapped with the photographs around it. The survey resulted in a total of 598 photographs and these were then combined to form an orthomosaic (merging them together to make a single large image). Alongside this a surface model was created as a result of Structure from Motion processing. This allows a three-dimensional surface model to be created from a series of two-dimensional images by using the location differences between each image. Careful enhancement of this surface model within QGIS software, supervised by Dr. Guglielmo Strapazzon and myself, allowed the visibility of smaller, archaeological features to be enhanced and a new interpretation for the hillfort interior to be completed. In addition to examining small features this method also allowed 26 cross-sections across all parts of the ramparts to be calculated and recorded. The analysis defined 133 platforms ranging in size from 17m2 up to 90m2 within the hillfort. Many of these platforms were in areas outside those previously defined where platforms existed. The survey not only defined previously unrecorded platforms but also allowed a more detailed analysis of platform size and orientation, and a consideration of where there seem to be groups or clusters of platforms. For example, larger sized platforms are spread across most of the area of the hillfort, where the smallest platforms are almost all in the south-western part of the hillfort. Of course, this is a long way from being able to explain why these differences may exist, whether they relate to different periods of occupation, because different activities took part in particular areas within the hillfort or for some other reason. However, this new level of detail not only provides a basis for future studies to monitor erosion and other changes on the site, but also allows more questions to be asked which archaeologists can explore in the future.
Orthomosiac of Mam Tor created from the UAV (drone) photography
2022 | ACID
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