Soil Site Reporter

Soil Associations


Soil and site characteristics
Very shallow very acid peaty upland soils over rock. Some thick peat. Steep craggy ground with extensive bare rock and scree.

Palaeozoic gritstone and sandstone
Cropping and Land Use
Stock rearing on wet moorland habitats of poor grazing value in the uplands; recreation.

Component soil series

Subgroup Series name Percentage WRB 2006 link
3.11 REVIDGE 30% Dystric Epileptic Histosols
10.13 CROWDY 20% Ombric Sapric Histosols
10.11 WINTER HILL 20% Ombric Fibric Histosols
Covers 103 km2 in England and Wales

Soilscapes Classification
Shallow very acid peaty soils over rock


Detailed Description

Shallow peaty soils of the Revidge series developed over conglomerate and sandstone occur with deeper peat soils of the Crowdy and Winter Hill series in this association. The soils are wet, very acid and infertile largely because of high rainfall and the nature of the parent rock. The terrain is generally rough and mountainous with heather moor and extensive rock outcrops. While most extensive in the mountains of west Wales (Rudeforth et al. 1984), it also occurs east of Manchester on the Millstone Grit of Longdendale, to the south on Kinder Scout and on the drier quartzite pavements of the Stiperstones of north Shropshire. Rankers occupy most of the association and have organic rather than humose topsoils. Peat soils are most extensive in the Peak District. On the Stiperstones surface stones are common and form polygonal patterns and aprons of scree around the rock outcrops. The association dominates the Rhinog hills north of Barmouth, where it rises to 700 m O.D. and receives an annual average rainfall of 2,000 mm. Rankers occupy up to half the land, peat soils about a fifth and bare rock a quarter to a third. There are small areas of stagnopodzols, including Belmont, Hiraethog and Hafren series and coarse loamy brown podzolic soils belonging to the Withnell series occupy bouldery lower slopes under local remnants of deciduous woodland. Most Revidge soils have organic rather than humose surface horizons. There is usually a thin surface layer of heather litter, which overlies the main horizon of well humified amorphous peat, which shows a blocky structure when moist or dry. This peat normally lies directly on bedrock or unweathered coarse scree and has a concentration of heather roots. Crowdy series which consists of deeper, acid, amorphous peats often rests on bedrock within 1 m depth. The shallower Crowdy profiles dry out occasionally encouraging humification and the development of a weak blocky structure. The included Winter Hill soils are dominantly fibrous, seldom if ever becoming dry. They may be solely rain fed or flushed with laterally moving water, but, because of the poor nutrient status of the underlying rock, the soil is very acid. Winter Hill soils are composed almost entirely of Sphagnum and cotton-grass remains. They rarely have rock within 1 m depth. Peat development is partly related to rainfall but differences in hardness, bedding and jointing of the rock account for much of the soil variation. In the Rhinog hills, the rock is extremely hard, yielding little fine earth. Where rock bedding is thickest, the land is roughly stepped with Revidge soils on the lip of each ledge above a sheer rock face. Peat thickens towards the backs of the ledges to give Crowdy soils. Winter Hill series occupies intricate patterns of mires where Eriophorum and Sphagnum have filled waterlogged hollows with fibrous peat. It also covers mountain tops to form blanket peat where rainfall is greatest. Bare rock is most extensive on Rhinog Fawr but to the south, where the rocks are more thinly bedded, terracing is less marked and peat soils confined to the mires. Shaly drift occupies pockets around the periphery of the gritstone outcrop. Stagnopodzols of the Belmont series occur where loamy drift covers the sandstone, and Hiraethog and Hafren series are found where the drift rests on shales. Stagnohumic gley soils are minor constituents in flush sites. On the lowest, often wooded, but boulder-strewn slopes, well drained Withnell soils have characteristically brightly coloured iron-enriched subsoils. Outcrops of shale on the ridge linking Diffwys to Llawlech carry loamy podzolic and stagnogleyic rankers, these have thin peaty mats over loamy horizons resting on shale at very shallow depth.

Soil Water Regime

These soils can absorb large volumes of water and are very wet during the winter, but because they are shallow they often dry out in the summer months.

Cropping and Land Use

The shallow peaty profiles, rockiness, exposure and steep slopes preclude agricultural improvement. Grazing value of the vegetation is poor and attempts at removal of the present vegetation could initiate rapid erosion. Afforestation is limited by the rugged terrain. Lodgepole pine is the preferred species but windthrow is likely to be an enduring limitation because of exposure and shallow soil. On the Stiperstones the vegetation is mostly short heather moor but in the Peak District wavy hair-grass (Deschampsia flexuosa) and purple moor grass (Molinia caerulea) are dominant with patches of bilberry (Vaccinium myrtillis) and mat-grass (Nardus stricta). The land mapped with this association in the Peak District in Longdendale and on Kinder Scout is generally wetter than elsewhere in the region. In the Rhinog hills these factors and the poor soil fertility are reflected in the small numbers of sheep that graze there during the summer. The vegetation has little value for grazing and improvement is possible only in a few peripheral areas. Surface horizons are often wet, poach easily and cannot support machinery or heavy stocking without serious damage. The soils are easily eroded, and footpaths are soon worn to rock. Afforestation is hampered by the rugged terrain which prevents drainage improvement and ridging for planting. Exposure and shallow waterlogged soils favour Lodgepole pine (Pinus contorta) but windthrow, particularly on western slopes, is an enduring limitation. The soils are almost continually wet and their vegetation has rarely if ever been burnt. They therefore support some of the most luxuriant heather and atlantic bryophyte communities in Britain. The patches of peat soils carry bog-moss (Sphagnum spp.) with varying amounts of deer grass (Trichophorum cespitosum), purple moor-grass (Molinia caerulea) and cotton-grass (Eriophorum spp.). Heather communities on the high peaks are the closest to dwarf montane heath in Wales and are accompanied by grassland of very low productivity. Woodland, which may once have covered the entire Rhinog hills, is now restricted to steep lower slopes. In places the terrain is scenically attractive and provides a valuable amenity for walkers.


Distribution Map

Note that the yellow shading represents a buffer to highlight the location of very small areas of the association.

Keys to component soil series


Typical Landscapes


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Citation: To use information from this web resource in your work, please cite this as follows:
Cranfield University 2024. The Soils Guide. Available: Cranfield University, UK. Last accessed 18/06/2024

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