7220 Petrifying springs with tufa formation (Cratoneurion)

European status and distribution

Petrifying springs are found in a number of EU Member States, in diverse environments from forest to open countryside.

UK status and distribution

Cratoneurion tufa formation is a relatively rare phenomenon in the UK. Petrifying springs occur as small, scattered flushes, and the total area of this habitat type is small.

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Site accounts

• Asby Complex Cumbria
  Asby is one of three sites selected on Carboniferous limestone in northern England. Sunbiggin Tarn and Moors is considered to be the most important site in Britain for petrifying springs with tufa formation, owing to the extent of the habitat type and the degree of conservation of spring-head structures. Nearby, Crosby Gill has areas of tufa with transitions to 7230 Alkaline fens and holds good populations of alpine bartsia Bartsia alpina. Large tufa mounds formed around spring-heads are frequent. There are transitions to a range of 7230 Alkaline fens, calcareous grasslands and acid heath.
• Beinn a' Ghlo Eastern Scotland
  Beinn a’Ghlo represents upland petrifying springs with tufa formations in Perthshire. Springs are associated with extensive exposures of metamorphosed limestone of the Dalradian series. Tufa-forming mounds are frequent and are found with other qualifying habitats (e.g. 7240 Alpine pioneer formations of Caricion bicoloris-atrofuscae, 6230 species-rich Nardus grasslands, and 8240 Limestone pavements). At Fealar Gorge tufa formations are found with mountain avens Dryas octopetala within the highest upland birch woodland known in Britain.
• Cairngorms Highlands and Islands, North Eastern Scotland
  The Cairngorms is one of three sites representing upland petrifying springs with tufa formation in north-east Scotland. The springs occur particularly at Inchrory, where there is an extensive series of springs associated with metamorphosed limestones and calc-schists. There are transitions to 7230 Alkaline fens, 6230 Species-rich Nardus grasslands and more acidic grassland and heath communities.
• Craven Limestone Complex North Yorkshire
  Craven is one of three Carboniferous limestone sites in northern England selected for petrifying springs with tufa formation. The site contains extensive complexes of tufa-forming springs associated with a wide range of other habitats, including 7230 Alkaline fens, calcareous grasslands, 8240 Limestone pavements, cliffs and screes. Locally calcareous springs emerge within areas of acid drift supporting heath and acid grassland. The flora of these habitat mosaics is outstandingly species-rich and includes many rare northern species, such as alpine bartsia Bartsia alpina and bird’s-eye primrose Primula farinosa.
• Creag nan Gamhainn Highlands and Islands
  Creag nan Gamhainn, a limestone crag and small, wooded gorge along the River Avon, is one of three sites selected in north-east Scotland for this habitat. An unusual feature of the site is the occurrence of Petrifying springs with tufa formation (Cratoneurion) within woodland. Although unusual in the UK, the habitat type is found in similar woodland situations in Fennoscandia. The mixed broad-leaved woodland has a ground flora rich in ferns. Other associated habitats include dry calcareous grassland and fen communities.
• Inchnadamph Highlands and Islands
  The petrifying springs with tufa formation on Dalradian Durness limestone at Inchnadamph are considered to be the best examples in the north-west Highlands on account of the large number of springs developed and their overall extent. Inaccessible springs on rocky slopes show a more continuous moss development while others are accessed by deer and are more open in structure as a result of trampling. They are formed on the slopes below outcrops of Durness dolomite. Petrifying springs occur at relatively low altitude at this site.
• Moor House - Upper Teesdale Cumbria, Tees Valley and Durham
  This is one of three sites in northern England that have extensive series of petrifying springs with tufa formation. At this site Carboniferous limestones are thinly-bedded amidst shales, sandstones and slates. Tufa springs often occur at the junction between limestone and these other, less permeable, rocks at a range of altitudes. Tufa springs are associated with calcareous glacial drift and can be found in calcareous grasslands, in fen systems of grazed pastures, associated with limestone scar cliffs and screes and amidst acid heathland and grassland. The flora is exceptionally rich and includes rare northern species such as bird’s-eye primrose Primula farinosa and Scottish asphodel Tofieldia pusilla.
• North Pennine Moors Cumbria, North Yorkshire, Northumberland and Tyne and Wear, Tees Valley and Durham
  The petrifying springs habitat is very localised in occurrence within the North Pennine Moors, but where it does occur it is species-rich with abundant bryophytes, sedges and herbs including bird’s-eye primrose Primula farinosa and marsh valerian Valeriana dioica.

SACs where this Annex I habitat is a qualifying feature, but not a primary reason for site selection

• Border Mires, Kielder - Butterburn Cumbria, Northumberland and Tyne and Wear
• Eller's Wood and Sand Dale North Yorkshire
• Eryri/ Snowdonia West Wales and The Valleys
• Hoy Highlands and Islands
• Ingleborough Complex North Yorkshire
• Morrone Birkwood North Eastern Scotland
• Rassal Highlands and Islands
• Strath Highlands and Islands
• West Fermanagh Scarplands Northern Ireland