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Gareth Farr1, Jonathan Graham2, Andy Marriott1 & Elliott Hamilton1. 2019. Survey of selected tufa forming sites in Staffordshire, UK. British Geological Survey Internal Report, OR/19/054.

1  British Geological Survey
2  Fenland Botanical Surveys

Site survey[edit]

Seven sites were surveyed. The details of all sites are provided in Table 1 and the location of sites is shown on Map 1. Photographs are included in Appendix 1 - Site photographs; All plant data (flowering plants and bryophytes) is provided in Appendix 2 - Plant data and water chemistry in Appendix 3 - Water chemistry.

Stanton Pastures[edit]

A small tuferous spring head underlain by Carboniferous Bowland Shales, situated in an open cattle-grazed field that feeds a small area of rushy pasture dominated by hard Rush Juncus inflexus and Jointed Rush Juncus articulatus. The immediate spring head has a raised tufa dome with the stonewort Chara vulgaris and bryophytes Palustriella falcata, Bryum pseudotriquetrum, Scorpidium cossonii all actively associated with tufa formation. Locally the two mosses Philonotis calcarea, Plagiomnium elatum also occur.

The adjoining spring-fed rushy pasture supports a large number of flush or wetland species including Marsh Marigold Caltha palustris, Cuckoo Flower Cardamine pratense, Star-sedge Carex echinata, Carnation Sedge Carex panicea, Marsh Thistle Cirsium palustre, Common Spotted Orchid Dactylorhiza fuschsii, Slender Spike-rush Eleocharis uniglumis, Hoary Willow-herb Epilobium parviflorum, Red Fescue Festuca rubra ssp. rubra, Yorkshire Fog Holcus lanatus, Greater Bird’s-foot Trefoil Lotus pedunculatus, Water Mint Mentha aquatica, Tufted Forget-me-not Myosotis laxa ssp. caespitosa, Meadow Buttercup Ranunculus acris, Ragged Robin Silene flos-cuculi, Marsh Arrow-grass Triglochin palustre and the moss Calliergonella cuspidata.

Slightly raised areas within the calcareous seepages support small flowering stands of Common Butterwort Pinguicula vulgaris with Quaking-grass Briza media, Devil’s-bit Scabious Succisa pratensis, Purging Flax Linum catharticum, Common Milkwort Polygala vulgaris and the moss Ctenidium molluscum. Slightly raised areas within the seepage area, above the influence of the calcareous flush water, are mildly acidic and of interest in supporting small numbers of calcifuge species including Common Cotton-grass Eriophorum angustifolium, Heath Louse-wort Pedicularis sylvestris and Tormentil Potentilla erecta.

Limestone Hill[edit]

Despite its name, the steeply eroded banks of the Ordley Brook comprised of red coloured Triassic age Sandstones. The wooded upper section of the Ordley Brook supports ancient sycamore, alder, ash, hazel woodland with occasional holly, guelder rose with ivy, bramble on the ground beneath. The brook descends a gradient below a minor road (Stanton Lane) where there are a number of small falls before the brook widens at the point of a larger crescent-shaped waterfall. Below this larger waterfall the brook is bordered on both sides by steep dripping vertical rock faces with tufa and the mosses Palustriella commutata, Eucladium verticillatum and very occasional Hart’s-tongue Fern Asplenium scolopendrium. The rock faces on the west side of the brook are more heavily shaded and dominated by Eucladium and only have localised stands of Palustriella.

Rocky terraces and the lower parts of rock faces (within the flood/splash zone of the brook) have dominant stands of the liverwort Pellia endiviifolia with other bryophytes including Cratoneuron filicinum, Conocephalum conicum, Rhizomnium punctatum and occasional stands of Wavy Bitter-cress Cardamine flexuosa. Locally, seepages with Opposite-leaved Golden Saxifrage Chrysosplenium oppositifolium and the moss Brachythecium rivulare also occur. Stones within the brook are dominated by the pleurocarpous moss Platyhypnidium ripariodes and localised stands of a tiny non fertile moss likely to be Fissidens crassipes.

Rich deep soil is present further up the banks of the wooded brook and supports a relatively rich ground flora including many species considered characteristic of ancient woodland including Wood Anemone Anemone nemorosa, Wild Garlic Allium ursinum, Bluebell Hyacinthoides non-scripta, Yellow Archangel Lamiastrum galeobdolon, Dog’s Mercury Mercurialis perennis, Wood Sanicle Sanicula europaea, Greater Stitchwort Stellaria holostea, Wood Sorrel Oxalis acetosella and Wood Speedwell Veronica montana.

Kirksteads Brook[edit]

This site comprises a steep section of the Kirksteads Brook complemented with a series of tufa dams bordered by ash, hawthorn, hazel, wych elm scrub woodland just above its outfall to the River Manifold. A series of tufa dams are present dominated by the bryophytes Pellia endiviifoliaand Platyhypnidium ripariodes. The rocky edge of the brook support stands of the moss Cratoneuron filicinum with occasional stands of Wavy Bitter-cress Cardamine flexuosa and the thalloid liverwort Lunularia cruciata. Marginal seepages have Opposite-leaved Golden Saxifrage Chrysosplenium oppositifolium, the moss Brachythecium rivulare and more open areas support ‘tall fen’ vegetation with Wild Angelica Angelica sylvestris, Common Valerian Valeriana officinalis, Greater Willowherb Epilobium hirsutum, Meadow-sweet Filipendula ulmaria. Shaded banks under scrub woodland support a moderate woodland ground flora including several species considered characteristic of ancient woodland including Sweet Wood-ruff Galium odoratum, Dog’s Mercury Mercurialis perennis, Wood Avens Geum rivulare and Greater Stitchwort Stellaria holostea. The bed of the brook, particularly in the lower section close to its outfall to the River Manifold, has a thick layer of gravel comprised of lose tufa and tufa-encrusted stones.

Trickle Ridge[edit]

A remarkable site within a woodland section of the Churnet valley where a series of tuferous seepages converge down a relatively steep slope to form a very large and impressive feature known locally as ‘trickle ridge’. This site has a history of local people maintaining a grove along the top ridge of the tufa block to concentrate the water flow, in turn, this influences the formation of new tufa and so greatly raise its height. The thickness of the tufa deposit is unknown but it protrudes from the slope of the bank, the underlying geology is reported to be the sandstone dominated Carboniferous Woodhead Hill Rock.

The upper springheads appear within ash, sycamore, alder woodland and are tuferous with Pendulous Sedge Carex pendula, Hart’s-tongue Fern Asplenium scolopendrium, Wavy Bitter-cress Cardamine flexuosa and the bryophytes Cratoneuron filicinum, Brachythecium rivulare, Pellia endiviifolia, Conocephalum conicum. Locally there are marginal stands of Opposite-leaved Golden Saxifrage Chrysosplenium oppositifolium and Wild Garlic Allium ursinum. The pleurocarpous moss Palustriella commutata occurs locally at the springheads on stones and tree roots and then becomes the dominant species covering most of the tufa block of ‘trickle ridge’ below along with very occasional strands of the shade tolerant moss Eucladium verticillatum.

The shaded banks away from the seepages support a moderate woodland ground flora including several species considered characteristic of ancient woodland including Wood Melick Melica uniflora and Wood Sorrell Oxalis acetosella. Seepage flow from the bottom of “trickle ridge” descends a steep vertical bank before collecting and outflowing under a footpath to the river. The large thalloid liverwort Conocephalum salebrosum occurs in the vicinity of this outfall. It was noticed that Palustriella had died back (going brown) in a few places on the top of ‘trickle ridge’ and that this die back most probably relates to the previous hot summer of 2018.

Emerald Cave[edit]

A site just to the west of Trickle Ridge where several tuferous springheads converge and have associated small tufa domes. The underlying geology is reported to be the sandstone dominated; Carboniferous Woodhead Hill Rock. One of the springheads has a concrete chamber constructed around it to collect water (see photograph in Appendix), and this has been confirmed as a private water supply. The upper springheads are dominated by the bryophytes Pellia endiviifolia, Brachythecium rivulare, Cratoneuron filicinum with occasional Hart’s-tongue Fern Asplenium scolopendrium, Wavy Bitter-cress Cardamine flexuosa, Opposite-leaved Golden Saxifrage Chrysosplenium oppositifolium, Wild Garlic Allium ursinum, Tufted Hair-grass Deschampsia cespitosa and the liverwort Conocephalum conicum towards the margins. Several tufa domes are present dominated by Palustriella commutata of which the largest is raised c.30 cm above ground level.

Lower down the slope, the seepages converge in more open woodland and are dominated by Pendulous Sedge Carex pendula with other taller species in small quantity including Wild Angelica Angelica sylvestris, Greater Willowherb Epilobium hirsutum, Meadow-sweet Filipendula ulmaria, Hoary Willowherb Epilobium parviflorum, Hogweed Heracleum sphondylium and Woody Nightshade Solanum dulcamara.

The shaded banks away from the seepages support a moderate woodland ground flora including several species considered characteristic of ancient woodland including Dog’s Mercury Mercurialis perenni and Yellow Archangel Lamiastrum galeobdolon. Significant stands of the tall invasive Himalayan Balsam Impatiens glandulifera were noted in several places. Seepages combine to one main channel before outflowing via an old stone structure under a public footpath to the Caldon Canal.

Booth’s Wood[edit]

RSPB Booth’s Wood and SCC Dale Spring SSSI. A small shaded seepage with some tufa within a swampy area of alder, grey willow woodland, within an area of Carboniferous Lower Coal Measures. The swampy ground flora includes Marsh Marigold Caltha palustris, Opposite-leaved Golden Saxifrage Chrysosplenium oppositifolium as well as small stands of the non-native species Pink Purslane Claytonia siberica, Himalayan Balsam Impatiens glandulifera. However, a seepage channel has the mosses Brachythecium rivulare, Cratoneuron filicinum (mostly growing on stones) and the Cratoneuron is associated locally with active tufa deposition.

The Petrifactions[edit]

This site comprises a wooded section of a stream ‘Cotwalton Drumble’. The stream descends eastwards via several small waterfalls to the valley bottom where it joins the ‘Mill Lades’ water courses. The stream widens and drops over a significant water fall below which a long series of vertical, dripping rock outcrops occur with tufa along the north bank. These tuferous outcrops are well known locally and referred to as ‘The Petrifactions’. The steep banks of the stream cut down sharply in places into the red coloured Triassic bedrock, including strata of the Mercia Mudstone Group and the Kibblestone member.

The woodland is ash-dominated with hazel, occasional guelder rose, oak, beech, holly, wych elm, ivy, bramble, dog rose, honeysuckle and alder on the immediate banks of the stream. The main area of dripping rock outcrops with tufa along the north bank are dominated by the bryophytes Palustriella commutata, Pellia endiviifolia, Eucladium verticillatum, Conocephalum salebrosum although most of the Palustriella stands appear stunted due to the heavy shading. Seepages below the rock outcrops and elsewhere on the south bank have Opposite-leaved Golden Saxifrage Chrysosplenium oppositifolium, Wavy Bitter-cress Cardamine flexuosa and the bryophytes Cratoneuron filicinum, Conocephalum conicum, Brachythecium rivulare. The rocky terraces that adjoin many parts of the stream have a broad number of river-edge or emergent species including Wild Angelica Angelica sylvestris, Fool’s Water-cress Apium nodiflorum, Meadow-sweet Filipendula ulmaria, Water-cress Nasturtium officinale sensu lato, Butterbur Petasites hybridus, Common Valerian Valeriana officinalis, Brooklime Veronica beccabunga, meadow Buttercup Ranunculus acris, Creeping Buttercup Ranunculus repens and bryophytes Rhizomnium punctatum, Lunularia cruciata.

The shaded banks away from the seepages support a broad number of common woodland ground species including Garlic Mustard Alliaria petiolata, Wild Garlic Allium ursinum, Hart’s-tongue Fern Asplenium scolopendrium, Lady Fern Athyrium felix-femina, Remote Sedge Carex remota, Wood Sedge Carex sylvatica, Enchanters Nightshade Circaea lutetiana, Tufted hair-grass Deschampsia cespitosa, Scaly Male-fern Dryopteris borreri, Broad Buckler-fern Dryopteris dilatata, Male-fern Dryopteris filix-mas, Cleavers Galium aparine, Herb Robert Geranium robertianum, Herb Bennet Geum urbanum, Rough-leaved Meadow-grass Poa trivialis, Soft Shield-fern Polystichum setiferum, Wood Dock Rumex sanguineus, Red Campion Silene dioica, Nettle Urtica dioica and bryophytes Atrichum undulatum, Eurhynchium striatum, Fissidens taxifolius, Kindbergia praelonga, Lophocolea bidentata, Oxyrrhynchium hians. A number of species considered characteristic of ancient woodland are also present locally including Bluebell Hyacinthoides non-scripta, Sweet Woodruff Galium odoratum, Wood Anemone Anemone nemorosa, Yellow Archangel Lamiastrum galeobdolon, Wood Melick Melica uniflora, Dog’s Mercury Mercurialis perennis, Greater Stitchwort Stellaria holostea, Wood Speedwell Veronica montana, Three-nerved Sandwort Moehringia trinervia, Primrose Primula vulgaris, Wood Sorrell Oxalis acetosella, Greater Woodrush Luzula sylvatica, the large leafy liverwort Plagiochila asplenioides and beside a strong seepage (SJ 9204834781) a stand of Hard Shield-fern Polystichum aculeatum. Vertical mildly acidic soil stream banks locally support other bryophytes including Dicranella heteromalla, Mnium hornum, Pseudotaxiphyllum elegans and Plagiochila porelloides.

The trunks and roots of larger trees have a number of common bryophytes including Amblystegium serpens, Hypnum cupressiforme, Isothecium myosuroides, Lophocolea heterophylla, Rhynchostegium confertum, Brachythecium rutabulum while upper branches and twigs of trees in the most humid areas support other epiphytic bryophytes including Metzgeria fruticulosa, Metzgeria furcata, Ulota bruchii, Orthotrichum affine and locally Common Polypody fern Polypodium vulgare. The moss Plagiomnium rostratum was noted in several places adjoining waterfalls while submerged rock terraces and stones of the stream are dominated by the robust aquatic moss Platyhypnidium ripariodes.

Rare of noteworthy plant species[edit]

Table 2 lists 4 plant species recorded during the brief survey that are considered rare or noteworthy (*) in a county (Staffordshire) context. The national threat status of flowering plants, included in brackets, is based on Stroh et al. (2014)[1]. All four of these noteworthy plants were recorded from the same site, Stanton Pastures (Stanton Pastures & Cuckoocliff SSSI).

Table 2    Rare or noteworthy plants.
Common name Latin name Status
Common Butterwort Pinguicula vulgaris * (Vulnerable)
Claw-leaved Hook-moss Palustriella falcata *
Intermediate Hook-moss Scorpidium cossonii *
Thick-nerved Apple-moss Philonotis calcarea *

Water chemistry[edit]

Description of data[edit]

Six water samples were collected and analysed, the field measurements, cations, anions nitrate and phosphate are summarised in Table 3. Field measurements including temperature 9.1–10.9°C, pH 7.1–8.4, electrical conductivity 420–810 µS cm-1 and HCO3- 196–407 mg/l are all indicative of groundwater chemistry (springs, seepages or baseflow dominated surface waters). The dominant cation is Ca and dominant anion HCO3- and the waters can generally be considered to be of ‘calcium-bicarbonate’ type which is expected for groundwater and some surface waters that have originated or interacted with calcareous bedrock (or quaternary deposits). Nitrate (N) is below the UK Threshold Value (UKTAG, 2014[2]) of 4.5 mg/l for low altitude petrifying springs in all sites except ‘The Petrifactions’ where nitrate may be derived from the local catchment and associated land use. There is no equivalent threshold value for phosphate, however all samples are below the limit of detection of <0.03 mg/l. The full water analysis is included in Appendix 3 - Water chemistry, however, a detailed discussion of the data is outside of the scope of this project.

Table 3    Selected Water Chemistry Data.

Nitrate[edit]

To date only nitrate has been considered in Water Framework Directive assessments for tufa forming springs (H7220) (e.g. UKTAG, 2014[2]). Nitrate can be expressed as NO3 or N and in this report we have converted NO3 to N, which for this habitat has a threshold value of 4.5 mg/l N (UKTAG, 2014[2]). It is important to stress that threshold values are simply a guide to where favourable or unfavourable condition may occur and that with time as more evidence is collected these threshold values may change. We are able to compare measured nitrate concentrations from this selected survey to the UKTAG threshold value of 4.5 mg/l and also to other studies carried out around the UK by the authors (Farr et al., 2014[3]; Graham & Farr, 2017[4]) using a box plot (Figure 1). The graph shows that the median value (red line) is below the threshold value, however the upper part of the box is possibly heavily influenced by the one high nitrate concentration measured from water at ‘The Petrifactions’.

Figure 1    Plot of nitrate concentrations — comparison with other UK studies.
(Data from Farr et al., 2014[3]; Graham & Farr, 2017[4] and this report © BGS UKRI).

References[edit]

  1. STROH, P A. ET AL. 2014. A Vascular Plant Red List for England. Botanical Society of the British Isles, Bristol.
  2. 2.0 2.1 2.2 UKTAG, 2014. Technical report on groundwater dependent terrestrial ecosystems (GWDTE) threshold values. UK Technical advisory group on the Water Framework Directive. Version 9 June 2014. Threshold Values www.wfduk.org
  3. 3.0 3.1 FARR, G, GRAHAM, J, and STRATFORD, C. 2014. Survey, characterisation and condition assessment of Palustriella dominated springs 'H7220 petrifying springs with tufa formation (Cratoneurion) in Wales. NERC, 211pp. (Natural Resources Wales Evidence Report No. 136, WL/NEC03832/13_14/T6, OR/14/043) (Unpublished)
  4. 4.0 4.1 FARR, G, and GRAHAM, J. 2017. Survey, characterisation and condition assessment of Palustriella dominated springs ‘H7220 Petrifying springs with tufa formation (Cratoneurion)’ in Gloucestershire, England. British Geological Survey, 141pp. (OR/17/020) (Unpublished)