A complete new view of Stonehenge’s landscape
Author: Renata Barradas Gutiérrez
Geospatial technologies are reshaping how archaeologists study and unlock history’s secrets. Stonehenge, one of the most famous landmarks and studied monuments in the United Kingdom, is being revealed with modern tools after centuries of excavations and theories. With more than 10,000 years of history, this UNESCO World Heritage site, including the wider landscape where it sits, has been digitally mapped to disclose hundreds of new features, brightening our understanding of this iconic cultural landscape.
To solve its mysteries, archaeologists from the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology (LBI ArchPro) and the University of Birmingham used geospatial technologies, such as laser scanning, magnetometry and ground penetrating radar combined with geographic information systems (GIS) and GNSS positioning, to create digital models at a true scale. The models include visible and invisible archaeological features that are part of a unified digital map.
This five-year archaeology project achieved what conventional excavation methods would have taken several decades to complete. The Stonehenge Hidden Landscapes Project is the largest endeavour of its kind, revealing hidden monuments around the area to understand how they interconnect with Stonehenge and its surrounding sacred landscape, and the people who built them.
Tools for non-invasive archaeology
The project, initiated in 2010, has the goal to create a detailed digital archaeological map of the entire landscape around Stonehenge through a seamless survey of the areas between known monuments using state-of-the-art geophysical surveys and remote sensing techniques.
To achieve this, non-invasive prospection methods were used to map the visible and invisible:
• Leica Geosystems robotic total stations and field software
• Leica Geosystems GNSS and GPS systems
• High-resolution magnetometer prospection
• Ground-penetrating radar (GPR)
• Electromagnetic induction
• 3D laser scanning
The new data retrieved with all this equipment threw light upon 10,000 years of human progress and the culture and people that flourished around them. The measurement data from ground-penetrating radar, high-resolution magnetometers and 3D laser scanning and geophysical instruments were combined within a GIS and then analysed to produce a multilayer digital map that shows how the landscape developed over thousands of years.
Finding lost monuments in vacant space
The biggest geophysical prospection survey ever done worldwide resulted in the discovery of several unknown monuments in the space surrounding the well-known stone circle.
“Developing non-invasive methods to document our cultural heritage is one of the greatest challenges of our time and can only be accomplished by adapting the latest technology, such as ground-penetrating radar arrays and high-resolution magnetometers,” said Professor Wolfgang Neubauer, director of the Ludwig Boltzmann Institute. “The developments of the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology offers the opportunity to carry out fundamental archaeological research at a scale and precision never previously attempted.”
GPR with Leica Geosystems GNSS antennas were used to map the underground with a geo-referenced local coordinate system. Using Leica Geosystems GPS systems, LBI archaeologists could establish a network of control points for tracking of the measurement equipment. Centimetre-accuracy and speed of the geo-referencing method were essential for this task.
As part of the challenges, the team had to develop all motorised systems and keep them running on site while accomplishing the work in short time periods. Repairs, modifications and developments had to be done on site and on their own. Prof. Neubauer and his team used Leica Geosystems GNSS and Leica Geosystems robotic total stations to track and navigate the novel motorized survey tools and to georeference the exact position of the “anomalies” revealed by the survey.
Anomalies detected by GPR in 2013, originally believed to be buried stones, have been staked out using Leica Geosystems total stations at Durrington Walls, 3 kilometres from the stone circle. The following excavations proofed the anomalies to be the stony refill of large pits for massive timber posts forming a major monument with a diameter of more than 500 metres predating the stone circle. The excavation project used fully 3D digital documentation including Leica Geoystems total stations and was awarded best project in the UK in 2016 by British Archaeology.
Ancient engineering ambitions revealed
Stonehenge is not isolated in its landscape. The findings helped to conceive Stonehenge, at the heart of a fast evolving and dynamic sacred landscape with a size of 40 kilometres squared. The survey of unprecedented scale and resolution became possible due to technological advancements and knowledge and uncovered the complex interconnections between the surviving monuments and many other new discovered monuments belonging to the lost civilizations. This allowed scientist and researchers to put it all together in one big picture – allowing to accurately tell Stonehenge’s story as part of a sacred landscape.
Stonehenge can only be understood by looking at the monuments around it and how that landscape has evolved. Using cutting edge, multi-sensor technologies, numerous archaeological structures could be uncovered, such as the new large timber monument at Durrington Walls. The results of the survey include 17 new Neolithic including barrows, henges, ditches and enormous prehistoric pits, dating to the periods before, contemporary and after the time when Stonehenge was at its zenith. Built to celebrate the passage of the sun, linking its position with the landscape, the new discoveries support the ritual significance of Stonehenge and its landscape on the Salisbury Plain in England.
Reinventing Stonehenge for this generation
What was initially carved with stone and bone tools has been unveiled with 21st century geospatial technology. The hundreds of new-discovered features allowed researchers to produce a more detailed archaeological digital map, thus, revealing the big picture of Stonehenge. Leica Geosystems equipment helped archaeologists to trace the marks of humans that occupied the landscape during the last 10,000 years and to contextualise the site in space and time into digital maps, which will guide how Stonehenge and its landscape are studied in the future.