Evolution of upland landscapes — Talla Earth Observatory

Talla soil map

The Talla project, which began in April 2005, is investigating the relationship between soils and the underlying geology in a typical area of British upland so we can better understand processes involved in climate change and flooding.

We produced a highly detailed physical model of the soil-geoscape of this small part of the Southern Uplands of Scotland, 35 km south of Edinburgh. It was the second soil-geoscape to be investigated in the UK, following a study of a representative riverine terrain developed on sedimentary rocks at Shelford in the Trent Valley.

The Talla Earth Observatory Site represents a typical glaciated upland soil-geoscape developed on resistant metasedimentary rocks.

Methods and techniques

Geotechnical data from one of the Talla boreholes

The soil-geoscape baseline was established by detailed field investigations that included:

  • geological mapping and augering; soil survey (NSRI) and micromorphology
  • terrestrial LiDAR survey, remote sensing/terrain analysis
  • drilling and trial pitting (soil sampling and property analysis)
  • geophysical surveys (automatic resistivity profiling, electrical resistivity tomography, ground penetrating radar, shallow seismic refraction etc.)
  • geotechnical testing (PANDA traverses, particle size etc.)
  • hydrogeological and geochemical surveying and sampling
  • geochronological and paleoenvironmental sampling and analysis (C14, cosmogenic dating, tephrachronology, pollen and plant macrofossil analysis etc.)

The baseline data were integrated within a 3D geoscience spatial model in GSI3D.

Monitoring at the Talla observatory site

Delivery

Apart from the 3D geoscience spatial model, further deliverables of this project include enhanced and tested survey capability producing a better scientific understanding of the soil-geology interface, as well as developing a chronologically constrained landscape evolution model for the Talla catchment. The survey techniques developed at the observatory are now to be applied to the flood monitoring and alleviation sites at Eddleston within the Tweed catchment in collaborative research with Dundee University funded by SEPA Tweed Forum.

Research Links

The project has developed external links with the Centre for Ecology and Hydrology (CEH), the National Soil Resources Institute (NSRI), Exeter University School of Geography, Archaeology and Earth Resources, Tweed Forum and UNESCO Centre for Water Law, Policy and Science, Dundee University as well presenting results to international audiences.

University of Exeter associates: Dr Chris Fogwill (Cosmogenic dating) and Dr Chris Turney (Palaeoenvironmental reconstruction).

University of Dundee associate: Dr Andrew Black (Hydrology)

Soils and the shallow geosphere

model of talla soils

A visualisation linking soils to geology

Work began in 2007 at the original Talla Earth Observatory site, which occupies about 3 km2 of ground on the interfluve between the Talla and Megget Reservoirs, some 15 km north-north-east of Moffat in the Scottish Borders (see digital terrain model).The lower portion of the 3D model shows the bedrock. Silurian weakly metamorphosed wacke sandstones of the Gala Group (grey) is overlain by till (blue) and bouldery moraines (green) on the valley sides. The valley floor is blanketed in peat; alluvial deposits occur along the Talla Water burn and bouldery periglacial head deposits mantle the mountain tops.

Soils mapping and characterisation shows that thick, commonly waterlogged, fibrous and humified peat soils (shown in yellow and pink) are developed on the floor and the sides of the main valley; stony sandy clay loams (shown in yellow, purple and sky blue) are developed on bouldery head on the mountain tops, on till and bedrock within the tributary valleys and on moraines in the upper reaches of the main valley. Bleached stony sandy loams (orange), commonly with ferruginous pans, blanket moraines lower in the valley. Thin clay loams cap bedrock crags (pale blue) while thin waterlogged gravel and peaty soils are developed on the floodplain of the Talla Water.

Contact

For more information about the Talla Earth Observatory contact Project Manager Clive Auton.