c.Form and date of most recent records of site

The first detailed map and account of the geology of St Kilda was produced in 1935. The most detailed modern investigations of the geology have been those that took place in the 1960s. In 1979 and 1980 the islands were researched and remapped by the British Geological Survey.

The marine geology to the west of Scotland has been researched only since the mid-1960s, before which it was almost totally unknown. In the 1960s, the British Geological Survey (BGS) commenced a systematic offshore regional mapping programme of the UK Continental Shelf. The BGS marine operations (run mainly during the late 1970s and early 1980s) involved the collection of shallow-seismic, gravity and magnetic data, supplemented by seabed sampling and coring, and the drilling of shallow boreholes to a depth of up to 300m below the seabed. Initially, this offshore work was funded by the Department of Education and Science, but subsequently major sponsorship was provided by the Department of Energy/Department of Trade and Industry. The BGS summarised the results of this programme in a series of geological maps at a scale of 1:250 000, which divides the shelf into named sheet areas. The St Kilda archipelago lies on the 1:250 000 St Kilda Sheet, which is also identified by the position of its south-west corner (57º N-10º W). The St Kilda geological sheet covers an area of one degree of latitude by two degrees of longitude and comprises the following three maps; Seabed Sediments, Quaternary Geology and Solid Geology. These maps were prepared largely from data collected during the BGS field programmes, supplemented by information from released hydrocarbon exploration data, universities, other institutes and the Hydrographic Office. To complement the map series, the BGS has also published a series of UK Offshore Regional Reports together with small-scale geological and geophysical maps and specialist reports.

The onshore Quaternary landforms and deposits were mapped by Sutherland et al. (1984). Sutherland et al. (1984) described the submerged shore platforms. Walker (1984) published the only detailed pollen diagram from Hirta.

Assessments of the scientific importance of the islands were made for the Geological Conservation Review. The islands are recognised as nationally important for British Tertiary Volcanic Province, Quaternary of Scotland and Coastal Geomorphology interests.

Following his visit to St Kilda in 1696 Martin Martin from Skye wrote ‘It is peculiar to those isles that they have never been described until now by any man that was a native of the country or had travelled them.’ His description of St Kilda, its wildlife and traditions remains a classic to this day. He was the first of many travellers to have visited St Kilda but until Calum Ferguson’s book Hiort –Fag na laigh a’ghrian was published in 1995 he remained one of the few Gaels to have written about the islands. Other than Jewell, Milner and Boyd’s 1974 volume Island Survivors about the Soay sheep, there has been no book devoted entirely to the wildlife of St Kilda. There has been, nonetheless, an impressive corpus of published papers devoted to many aspects of the sciences.

Various scientists have visited the islands, from J. Waterston in 1905 and W. Eagle Clarke in 1910-1911 to James Fisher (who was first to census the gannets) in 1939 and 1947-1949. An important contribution had been made by the Oxford-Cambridge Expedition in 1931, immediately following the evacuation. Edinburgh University followed in 1948, and Glasgow University (headed by J. Morton Boyd) in both 1952 and 1956. The first Nature Conservancy warden, Ken Williamson, studied bird migration, wrens, and snipe and even found time to make some of the first maps of the antiquities. David Boddington and Estlin Waters made good use of their time whilst posted at the MoD Base on St Kilda in the late 50s/early 60s, to study seals, wrens, petrels and other birds. Subsequent wardens have contributed biological records, alongside visiting scientists interested in specific aspects such as lichens (by Oliver Gilbert) and fungi (by R. Watling). There have been various studies of the vegetation and plant communities, notably by Gwynne Milner and Hornungh in Island Survivors, with a recent National Vegetation Classification undertaken by Alan Booth in 1996. Professor M. Crawley has also studied the vegetation with emphasis on the impact of the Soay sheep. Cambridge University took up the sheep studies in 1985, under Professor T. Clutton-Brock, and now several other universities are contributing their expertise in diverse aspects of this important project.

M. P. Harris undertook a classic study of Atlantic puffins on Dun and, with S. Murray, assembled a checklist of the birds of St Kilda in 1978; Murray updated this in 2002, collating all previous records and counts. The seabird colonies of St Kilda were censused completely most recently in 1999 and 2000 by the UK Joint Nature Conservation Committee; this census reaffirmed the national and international importance of St Kilda’s seabird community. The northern gannet colony on Boreray and associated stacks is surveyed every 10 years.

In addition, the JNCC monitors northern fulmar, common guillemot and razorbill numbers in selected plots every three years, since1990. Scottish Natural Heritage has annually monitored breeding productivity of northern fulmars (since 1989) and of black-legged kittiwakes (since 1986) while the CEH (Centre for Ecology and Hydrology; formerly the Institute of Terrestrial Ecology) analyse northern gannet eggs at regular intervals, for the presence of pesticides and other chemical pollutants.

There have been various opportunistic but mostly incomplete surveys of some seabird species except the storm-petrels over the past few decades.

The historical bathymetric and seabed character data are limited, as shown on Admiralty Chart 2524. Most soundings are from lead line surveys carried out between 1857 and 1909. More detailed surveys of Village Bay and Glen Bay were undertaken between 1957-1964, together with a limited number of lines of soundings to the east of Hirta and south of Boreray between 1956-1979.

Two recent books on St KildaThere have been two recent surveys that have comprehensively covered both the intertidal and subtidal habitats around St Kilda. The first was a survey conducted by Scottish Natural Heritage in 1997 that involved a complete mapping of the intertidal biotopes for all the islands and the main stacs, together with broad scale mapping of the seabed in the areas adjacent to the islands using a RoxAnn acoustic ground discrimination system with ground truthing provided by scuba diver observations, underwater video and grab samples. A second survey was carried out in 2000 jointly by Scottish Natural Heritage and the Fisheries Research Services laboratory, Aberdeen that mapped the extensive areas of sea bed between the islands and a substantial area to the northwest of Soay. This survey employed a range of acoustic survey techniques such as RoxAnn, multibeam swathe bathymetry and side-scan sonar together with towed video and ROV and extensive grab sampling in the areas of soft sedimentary sea bed. These have resulted in detailed maps of the seabed topography and bathymetry together with the broad-scale distribution of benthic biotopes being produced.


St Kilda benefits from having a number of particularly detailed records of its historic buildings and archaeological sites. The base-line record was produced by the Royal Commission on the Ancient and Historical Monuments of Scotland, consisting of detailed survey of the Village Bay area, Gleann Mor, and other principal sites, plus ground and some elevational/cross-sectional illustrations of standing buildings and other selected structures.

The RCAHMS survey has more recently been supplemented by more detailed pieces of work, including a comprehensive survey of the 1,430 or so cleitean on the islands by Dr Mary Harman, and by condition surveys of houses, blackhouses, other buildings, walls and selected cleitean by Lorna Johnstone, NTS St Kilda Archaeologist 1996-2000. Most of this information is now in the public domain, being held in the National Monuments Record of Scotland.

As noted above, more detailed archaeological and palaeoenvironmental investigations have also take place recently, the results of an on-going research partnership between The National Trust for Scotland and the Universities of Glasgow and Durham, and also by the Universities of Sheffield and Wales Aberystwyth and by the University of Aberdeen. This and other archaeological, historical and scientific research into the cultural heritage of St Kilda is promoted and guided by the St Kilda Archaeological Research Committee; a panel of invited individuals and representatives from bodies with an interest in the islands’ heritage.