How collaborative scientific investigation will help conserve Glasgow’s hidden geological gem

A team from Historic Environment Scotland (HES) is helping us to safeguard the future a 325 million year old geological site. Our blog today comes from Dr Lyn Wilson, Digital Documentation Manager,  Sarah Hamilton, Conservation Scientist and James Hepher, Surveyor/Spatial Analyst, all from HES.

A perspective point cloud view through the building across the fossilised tree stump area. The colours represent intensity of the reflected laser beam.

A perspective point cloud view through the building across the fossilised tree stump area. The colours represent intensity of the reflected laser beam.

Tucked away in a quiet corner of Glasgow’s Victoria Park lies the hidden geological gem of Fossil Grove Site of Special Scientific Interest. Discovered during landscaping of the park in 1887, the site contains the beautifully preserved casts of 325 million year old Carboniferous Lycopod tree stumps and their Stigmarian root systems. Recognised at the time as a site of great interest and importance, the Victorian city fathers chose to encapsulate the site as a visitor attraction rather than send the fossils to a museum. As a result of this forward-thinking, Fossil Grove is the only site in the world where these trees have been preserved in their growth positions and is considered one of the world’s first examples of geoconservation.

However, in recent years the much modified Victorian building has begun to suffer from water penetration problems leading to discolouration and decay of some areas of the fossil exhibits. HES offered the services and expertise of their Digital Documentation and Conservation Science teams to undertake a 3D laser scan and mineralogical analysis to help gain a better understanding of the site and the problems faced. It is hoped that this work will help to inform future recommendations for improving both the fabric of the building and its environmental conditions, in order to safeguard and ensure the continued preservation of this fascinating site for future generations.

Point cloud plan annotated with sampling locations for salt efflorescence analysis.

Point cloud plan annotated with sampling locations for salt efflorescence analysis.

The Conservation Science team have used a technique known as X-Ray Diffraction (XRD) to analyse the mineralogical make up of the main rock types found at Fossil Grove, and to identify the salt growths which are causing discolouration to some of the rock surfaces. Only tiny quantities of material are required for this type of analysis, meaning that already loose fragments of rock were used and no further damage to the fossil exhibits was necessary. Interpretation of the results is ongoing, but by identifying the salts present at the site, we can assess where they may have come from, their damage potential, possible methods for removal and determine the most suitable environmental conditions required inside the building to minimise their future growth.

James laser scanning around the exterior of the Victorian building.

James laser scanning around the exterior of the Victorian building.

The Digital Documentation team came armed with two laser scanners, with James undertaking a traverse around the outside of the building with our survey-grade Leica Geosystems ScanStation P40 scanner and Lyn covering the interior with our light-weight Faro X350 scanner which is set up on a photographic tripod – well suited to scanning close to the fossils themselves. The two scanners had overlapping areas at the building’s doorways, allowing the exterior and interior scans to be joined together giving us one overall 3D ‘point cloud’.

Lyn laser scanning the fossilised tree stumps.

Lyn laser scanning the fossilised tree stumps.

A point cloud is a 3D representation obtained from laser scanners or other digital documentation equipment, with accurate spatial coordinates representing surface geometry. Point clouds can be processed and developed in lots of different ways, making them useful for conservation, site management, interpretation and education – just to name a few applications! Within HES, our current task is to record all 336 heritage sites we look after using 3D laser scanning, primarily for conservation purposes. It allows us to monitor the condition of sites by comparing laser scan data from different time periods. We do this to check on coastal erosion at Skara Brae for example, every two years.

A perspective point cloud view through the building across the fossilised tree stump area.

A perspective point cloud view through the building across the fossilised tree stump area.

We are fortunate to have gained a lot of experience over the years working in partnership with The Glasgow School of Art on The Scottish Ten project. This saw our combined team digitally record all of Scotland’s World Heritage Sites in 3D plus fantastic international heritage sites such as Mount Rushmore and the Sydney Opera House. The data we captured has been used to provide virtual access, create architectural visualisations and virtual reconstructions, to help in site management and to bolster UNESCO World Heritage nominations.

Back in Scotland, part of our role is to support our partners in the sector so we were really pleased to be able to help SNH at the gem that is Fossil Grove. We hope our scientific analysis and 3D records will be of practical use in the conservation process, as well as supporting the future architectural redesign and interpretation process.

Find out more about the work of HES’s Conservation Science and Digital Documentation teams and about the Scottish Ten Project.

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