Dirlot Gorge
Condition (NatureScot)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| F1 | Moine | Favourable | — | 2009-05-07 |
| F2 | Scrub | Unfavourable No Change | — | 2023-05-23 |
Geology & landscape
Geological Feature: Gorge / Ravine · Geological Period: Devonian · Rock Type: Sandstone
Landscape processes: Fluvial
Description
DIRLOT GORGE Dirlot Gorge Site of Special Scientific Interest (SSSI) covers a 1km stretch of the River Thurso, 20km south of Thurso. The site is nationally important for the geological formations that have been exposed in the gorge and for the scrub woodland that grows on the steep slopes of the gorge. Moine geology Dirlot Gorge SSSI has a rare example of an exposure of the Moine rocks that lie underneath the sandstones and flagstones of Caithness. This site has two small, isolated exposures of Moine rock, that are approximately 1000-870 million years old. The Moine rock is overlain by much younger ‘Old Red Sandstone’ that was deposited in the Middle Devonian time period (410-360 million years ago). The exposures also demonstrate the nature of contact between these two rock types. Scrub woodland This site is the best example of the few remaining fragments of broadleaved woodland in the interior of Caithness. The scrub woodland at Dirlot Gorge SSSI is predominantly downy birch Betula pubescens and hazel Corylus avellana with a number of other species of stunted trees and shrubs including rowan Sorbus aucuparia, aspen Populus tremula, hawthorn Crataegus monogyna, bird cherry Prunus padus, and the nationally scarce downy currant Ribes spicatum. The ground flora is species-rich and contains the nationally scarce shade horsetail Equisetum pratense and herbs such as sanicle Sanicula europaea, wood avens Geum urbanum and red campion Silene dioica.
Species mentioned
Show the 11 species mentioned in the description, with red-list status| English name search for this in other sites |
Latin name search with Google |
IUCN / Red List | Type | Family |
|---|---|---|---|---|
| shady horsetail | Equisetum pratense | LC | herb | equisetaceae |
| herb bennet | Geum urbanum | LC | herb | rosaceae |
| sanicle | Sanicula europaea | LC | herb | apiaceae |
| red campion | Silene dioica | LC | herb | carophyllaceae |
| hawthorn | Crataegus monogyna | LC | shrub | rosaceae |
| downy currant | Ribes spicatum | NT | shrub | grossulariaceae |
| downy birch | Betula pubescens | LC | tree | betulaceae |
| hazel | Corylus avellana | LC | tree | corylaceae |
| aspen | Populus tremula | LC | tree | salicaceae |
| bird cherry | Prunus padus | LC | tree | rosaceae |
| rowan | Sorbus aucuparia | LC | tree | rosaceae |
Insects to look out for
These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.
| Species | Status | Via host-plant |
|---|---|---|
| Figure of eight Diloba caeruleocephala |
Endangered | Crataegus spp., Prunus spp. |
| Dark bordered beauty Epione vespertaria |
Endangered | Populus tremula |
| The lappet Gastropacha quercifolia |
Endangered | Crataegus monogyna, Prunus spp. |
| Scarce vapourer Orgyia recens |
Endangered | Betula spp., Corylus avellana, Crataegus spp. |
| Mouse moth Amphipyra tragopoginis |
Vulnerable | Crataegus spp. |
| The sprawler Asteroscopus sphinx |
Vulnerable | Betula spp., Corylus avellana, Crataegus spp., Populus spp., Prunus spp. |
| Broom moth Ceramica pisi |
Vulnerable | Betula spp. |
| Scarce chocolate-tip Clostera anachoreta |
Vulnerable | Populus spp., Populus tremula |
| Mottled umber Erannis defoliaria |
Vulnerable | Betula spp., Corylus avellana, Crataegus spp., Populus tremula, Prunus padus, Sorbus aucuparia |
| The lackey Malacosoma neustria |
Vulnerable | Corylus avellana, Crataegus monogyna, Prunus spp. |
| Pale brindled Phigalia pilosaria |
Vulnerable | Betula pubescens, Corylus avellana, Crataegus monogyna, Populus spp. |
| Grizzled skipper Pyrgus malvae |
Vulnerable | Geum urbanum |
| Early moth Theria primaria |
Vulnerable | Crataegus monogyna |
| Pale eggar Trichiura crataegi |
Vulnerable | Betula spp., Corylus avellana, Crataegus monogyna, Populus spp. |
| No common name Zeugophora turneri |
Vulnerable | Populus tremula |
| Flounced chestnut Agrochola helvola |
Near Threatened | Betula spp., Crataegus monogyna |
| Beaded chestnut Agrochola lychnidis |
Near Threatened | Crataegus monogyna |
| Grey chi Antitype chi |
Near Threatened | Crataegus monogyna |
| Purple emperor Apatura iris |
Near Threatened | Populus tremula |
| Garden tiger Arctia caja |
Near Threatened | Sorbus aucuparia |
| Minor shoulder-knot Brachylomia viminalis |
Near Threatened | Populus tremula |
| The sallow Cirrhia icteritia |
Near Threatened | Populus spp. |
| Kentish glory Endromis versicolora |
Near Threatened | Betula pubescens |
| Large thorn Ennomos autumnaria |
Near Threatened | Betula spp., Corylus avellana, Crataegus spp., Populus spp., Prunus spp. |
| September thorn Ennomos erosaria |
Near Threatened | Betula spp. |
| Autumnal rustic Eugnorisma glareosa |
Near Threatened | Betula spp. |
| Grey pug Eupithecia subfuscata |
Near Threatened | Crataegus monogyna, Populus tremula |
| Double dart Graphiphora augur |
Near Threatened | Betula spp., Crataegus spp. |
| White prominent Leucodonta bicoloria |
Regionally Extinct | Betula spp. |
Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.
Plant communities
W21 — Hedgerow scrub, Mixed scrub
Crataegus monogyna-Hedera helix scrub
Matches 4 species from the description above: Corylus avellana, Crataegus monogyna, Geum urbanum, Silene dioica
Show 81 indicator speciesHedera helix, Salix cinerea, Acer pseudoplatanus, Ilex aquifolium, Betula pendula, Corylus avellana, Fagus sylvatica, Quercus robur, Fraxinus excelsior, Malus sylvestris, Sorbus aria, Taxus baccata, Ulmus glabra, Ulmus procera, Sambucus nigra, Viburnum lantana, Euonymus europaeus, Cornus sanguinea, Juniperus communis, Ligustrum vulgare, Clematis vitalba, Rhamnus cathartica, Crataegus laevigata, Crataegus monogyna, Prunus spinosa, Juncus effusus, Plagiomnium undulatum, Brachythecium rutabulum, Kindbergia praelonga, Rhynchostegium confertum, Tamus communis, Heracleum sphondylium, Torilis japonica, Arum maculatum, Arctium minus, Cirsium arvense, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Stellaria graminea, Stellaria holostea, Stellaria media agg., Calystegia sepium, Mercurialis perennis, Geranium robertianum, Iris foetidissima, Glechoma hederacea, Lamium purpureum, Origanum vulgare, Stachys sylvatica, Teucrium scorodonia, Allium ursinum, Hyacinthoides non-scripta, Circaea lutetiana, Rumex sanguineus, Anemone nemorosa, Ranunculus repens, Fragaria vesca, Geum urbanum, Potentilla sterilis, Poterium sanguisorba, Rosa arvensis, Rosa canina, Rubia peregrina, Rubus fruticosus agg., Galium aparine, Urtica dioica, Viola riviniana, Anisantha sterilis, Arrhenatherum elatius, Brachypodium pinnatum, Brachypodium sylvaticum, Bromopsis erecta, Dactylis glomerata, Elytrigia repens, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris filix-mas
W22 — Hedgerow scrub, Mixed scrub
Prunus spinosa-Rubus fruticosus scrub
Matches 3 species from the description above: Corylus avellana, Geum urbanum, Silene dioica
Show 49 indicator speciesHedera helix, Acer campestre, Corylus avellana, Ulex europaeus, Prunus spinosa, Plagiomnium undulatum, Brachythecium rutabulum, Eurhynchium striatum, Kindbergia praelonga, Thuidium tamariscinum, Atrichum undulatum, Lophocolea bidentata, Achillea millefolium, Cardamine flexuosa, Lonicera periclymenum, Moehringia trinervia, Silene dioica, Silene uniflora, Stellaria media agg., Mercurialis perennis, Geranium robertianum, Stachys sylvatica, Teucrium scorodonia, Hyacinthoides non-scripta, Oxalis acetosella, Digitalis purpurea, Plantago lanceolata, Veronica chamaedrys, Armeria maritima, Rumex acetosa, Filipendula ulmaria, Geum urbanum, Rosa canina, Rubus fruticosus agg., Rubus idaeus, Galium aparine, Urtica dioica, Viola riviniana, Agrostis capillaris, Brachypodium sylvaticum, Dactylis glomerata, Festuca rubra, Holcus lanatus, Holcus mollis, Poa trivialis, Asplenium scolopendrium, Pteridium aquilinum, Dryopteris borreri, Dryopteris filix-mas
A14 — Fast flowing river and stream
Myriophyllum alterniflorum community
Show 15 indicator speciesIsolepis fluitans, Juncus bulbosus, Fontinalis antipyretica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Lemna minor, Callitriche stagnalis, Littorella uniflora, Potamogeton filiformis, Potamogeton gramineus, Potamogeton natans, Ranunculus peltatus, Chara spp., Nitella hyalina
A17 — Chalk river and stream, Fast flowing river and stream
Ranunculus penicillatus ssp. pseudofluitans community
Show 11 indicator speciesBerula erecta, Nasturtium officinale, Elodea canadensis, Lemna minor, Callitriche stagnalis, Veronica beccabunga, Polygonum amphibium, Polygonum hydropiper, Potamogeton crispus, Potamogeton pectinatus, Ranunculus penicillatus ssp. pseudofluitans
A18 — Fast flowing river and stream
Ranunculus fluitans community
Show 12 indicator speciesFontinalis antipyretica, Fontinalis squamosa var. curnowii, Myriophyllum alterniflorum, Myriophyllum spicatum, Elodea canadensis, Mentha aquatica, Lemna gibba, Lemna minor, Potamogeton perfoliatus, Ranunculus fluitans, Glyceria fluitans, Phalaris arundinacea
A9 — Fast flowing river and stream, Marginal and inundation, Pond ditch and canal, Sluggish river and stream
Potamogeton natans community
Show 20 indicator speciesSchoenoplectus lacustris, Juncus bulbosus, Sparganium angustifolium, Sparganium erectum, Sparganium minimum, Alisma plantago-aquatica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Elodea canadensis, Lemna minor, Lemna trisulca, Nymphaea alba, Callitriche platycarpa, Callitriche stagnalis, Littorella uniflora, Potamogeton natans, Ranunculus trichophyllus, Glyceria fluitans, Chara subspinosa
W20 — Montane scrub
Salix lapponum-Luzula sylvatica scrub
Show 107 indicator speciesSalix arbuscula, Salix cinerea, Salix lapponum, Salix myrsinites, Salix phylicifolia, Salix reticulata, Empetrum nigrum, Calluna vulgaris, Salix lanata, Vaccinium myrtillus, Vaccinium uliginosum, Carex atrata, Carex bigelowii, Carex binervis, Carex flacca, Luzula multiflora, Luzula sylvatica, Huperzia selago, Selaginella selaginoides, Aulacomnium palustre, Mnium hornum, Philonotis fontana, Plagiomnium undulatum, Rhizomnium punctatum, Dicranum bonjeanii, Dicranum majus, Dicranum scoparium, Fissidens adianthoides, Racomitrium lanuginosum, Calliergonell cuspidatum, Ctenidium molluscum, Hylocomium splendens, Hypnum callichroum, Hypnum cupressiforme, Palustriella commutatum, Plagiothecium denticulatum, Plagiothecium undulatum, Pleurozium schreberi, Ptilium crista-castrensis, Rhytidiadelphus loreus, Rhytidiadelphus squarrosus, Rhytidiadelphus triquetrus, Sanionia uncinata, Scorpidium revolvens, Thuidium tamariscinum, Atrichum undulatum, Polytrichastrum alpinum, Sphagnum capillifolium, Sphagnum fallax, Sphagnum girgensohnii, Sphagnum palustre, Sphagnum russowii, Sphagnum squarrosum, Sphagnum subnitens, Sphagnum teres, Barbilophozia barbata, Chiloscyphus polyanthos, Diplophyllum albicans, Lophocolea bidentata, Plagiochila porelloides, Ptilidium ciliare, Scapania undulata, Cladonia squamosa, Peltigera canina, Angelica sylvestris, Caltha palustris, Hieraclium spp., Saussurea alpina, Solidago virgaurea, Campanula rotundifolia, Succisa pratensis, Valeriana officinalis, Rhodiola rosea, Vaccinium vitis-idaea, Thymus praecox, Epilobium anagallidifolium, Dactylorhiza viridis, Euphrasia officinalis, Rhinanthus minor, Oxalis acetosella, Oxyria digyna, Polygonum viviparum, Rumex acetosa, Anemone nemorosa, Ranunculus acris, Thalictrum alpinum, Alchemilla alpina, Alchemilla glabra, Filipendula ulmaria, Geum rivale, Galium boreale, Galium saxatile, Saxifraga aizoides, Saxifraga hypnoides, Saxifraga oppositifolia, Saxifraga stellaris, Viola riviniana, Agrostis canina, Agrostis capillaris, Anthoxanthum odoratum, Deschampsia cespitosa, Deschampsia flexuosa, Festuca ovina, Festuca rubra, Nardus stricta, Dryopteris dilatata, Phegopteris connectilis