Blackhall Rocks


This beach photo taken from the top of the Magnesian limestone cliff outcrops laid down during the late Permian ( 300-250 mya). Formed by lagoonal deposits left by the rising and falling levels of the Zechstein sea, various formations can be seen including the Hesleden Biostrome from the beach.

A closer view of the rubble on the beach reveals a stony residue of colliery waste dumped on the beach from local mine workings. The colliery closed in the 1990’s but it was left for the tides to disperse the spoil out to sea. There is still a detectable sulphurous smell.


The cliffs look more imposing from the beach.


The laminations in the Biostrome are visible from close up as tightly packed thin layers. Finely laminated horizontal layers within the rock, each no more than a millimetre thick were formed from layers of filamentous blue-green algae that gradually accumulated on the shallow bed of the tropical sea. The Biostrome consists almost entirely of dolomite rock and comprises a thick and highly varied boulder conglomerate overlain by a thicker unit of algal laminites. The conglomerate is formed mainly of rolled cobbles and boulders derived by erosion of the underlying (but unexposed) reef-flat rocks of the Ford Formation.


Stromatolites occur in the form of large domes up to 20m across and 3m high, pictured below. They are intriguingly displayed on the shore. Structures of this size are currently unique to the UK, and rare in marine Permian strata generally.


They are more difficult to spot in the cliffs, however, this picture shows the convex dome shaped ‘Crinkly Beds’ of this upper (stromatolitic) part of the biostrome.


Evidence of a fault is shown below in the different strata on either side of the slipped glacial till. This fault between Limekiln Gill and Cross Gill brings the Seaham Formation and Seaham Residue (left) into contact with the Roker Dolomite Formation (right). The base of the Roker dolomite rises to the cliff top beneath the boulder clay.


A closer view of the Seaham residue, predominantly thin-bedded limestone (calcite mudstone/wackestone with some interbedded coquina , packstone, grainstone, mudstone and concretionary limestone) with some dolostone.


Towards the south, a block of the Roker formation had fallen on the beach. Not only were mud slides dripping down the cliffs; occasional rock falls littered the beach. The area, in the longer term, is under going progressive erosion.


The Roker formation is a cream, oolitic dolostone with subordinate thin beds of fine-grained dolomite and breccias. It rests on the Concretionary Limestone Formation (seen above at the bottom) as rounded cannonball-like strata that occurs above the Hartlepool Anhydrite Formation offshore with a dissolution residue that overlies the Ford Formation onshore.

The glacial tills are 24 m deep of southwards-thickening Quaternary (late Devensian)  deposits overlying up to 10 m of Magnesian Limestone. They form a layered sequence of two stony clays separated by a sand and gravel layer from which perennial seepages cause instability and slips.


The site is noted for cliff top magnesian grassland and plants such as Sea Spleenwort (Asplenium marinum ). It grows in crevices and fissures in rocks, caves and walls near the sea and within the sea-spray zone.


The beach at Black Hall Rocks contains some of the largest cave formations to be found on the Durham coastline, the magnesian limestone cliffs here measure 15–32m in height. The Gin Cave is an example of a Sea (Littoral) Cave. Colourful red algae, probably Hildenbrandia rubra decorates the walls.


A  tantalizing view of the beach from within one of the caves. Caves are formed by the action of destructive waves hitting the cliffs with great force. The action concentrates on weak points within the rock, this may be a fault line or the bedding planes of sedimentary rocks, such as limestone.


Caves in headlands may eventually erode right through to create an Arch in the rock. This will continue to erode and eventually the arch will collapse leaving a free-standing pillar of rock known as a Stack. The coastline here used to feature many stacks. These are no longer present through either natural causes or human intervention.


A group of ringed plover and a few Redshank were seen patrolling the tideline.




Blyth South Beach to St Mary’s in December

This picture of South Beach shows the blue sky and white topped waves driving onto the sands invigorating dog walkers, sailors and surfers. The dunes are well covered in Marram and Lyme grass.


The wind turbines on the horizon are two of the five that comprise Blyth Offshore Demonstrator Wind Farm.  Newly installed, they have gravity based foundations that ‘float and submerge’ in the 40 meter depth of water. They provide electricity for 34,000 homes and were built locally in Wallsend.


The driving seas had whipped up foam and rainbow bubbles on the shore. According to the wiki: Sea foam, ocean foam, beach foam, or spume is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter (including proteins, lignin, and lipids) derived from sources such as the offshore breakdown of algal blooms.


A raft of Eider Duck had no trouble negotiating the swells. They are true sea ducks feeding on molluscs especially mussels. A few of the males were still in their colourful breeding plumage. Eider are a feature of the Northumberland coast and are Amber listed.


Oyster catchers were quick to feed on the rocks at Seaton Sluice as the tide receded. Like the Eider, they also eat cockles and mussels when at the coast.


While walking along I took notice of the plants in flower such as the Prickly Sow thistle (Sonchus asper) shown below. The plants still in bloom were mostly ruderals like Groundsel (Senecio vulgaris), Daisy (Bellis perennis), Ragwort (Jacobaea vulgaris), Dandelion (Taraxacum agg.), Chickweed (Stellaria media), Shepherd’s purse (Capsella bursa-pastoris), Yarrow (Achillea millefolium), Annual meadow grass (Poa annua), White Dead Nettle (Lamium album). Among the many sea-side plants, Thrift (Armeria maritima), though not in flower, had dried flower heads on show.


As the tide ebbed many birds flew in to feed, like this Curlew. Redshank were fairly numerous but there were some Dunlin, Lapwing, Turnstone and two pairs of Ringed plover. Gulls of various kinds and crows had also taken to the rocks.


The lake on the bird reserve held a pair of Canada Geese, Mallard, Heron, Moorhen and a flock of Teal. On the scrub by the wetland I had caught a glimpse of a small bird with a white belly. Although I wondered what it could be, a bird watcher later told me to watch out for a pair of Snow Bunting. It seems likely the birds I had seen were Snow Bunting (Plectrophenax nivalis). Regularly wintering along the coast they are Arctic specialists, though a few nest in the Cairngorms. On Whitley Beach, avoiding the walkers and dogs, a flock of Sanderling, another Arctic breeder also here for the winter, was in constant movement along the water’s edge by the tide wrack.


At Seaton Sluice, on a stone wall, this Acarospora fuscata lichen looked like dried mud.  Crab’s Eye Lichen (Ochrolechia parella) was covering the wall tops in large white patches.


This Lichen looked like Lecanora campestris with its dark red apothecia.


On the same wall, always worth a visit, a brightly coloured Caloplaca glowed, perhaps C verruculifera?


Lichen often grow on top of one another. The whitish base lichen is (Apsicilia caesiocinerea) but there is a Lecanora possibly L dispersa growing on top.




Wind Farm

Sea foam

Lindisfarne- Snook and Saltmarsh Plants

Lindisfarne is an SSSI site comprising a wide range of habitats including stable sand dunes, slacks, extensive intertidal sand and mudflats. This site supports a number of rare plants, invertebrates, overwintering and breeding birds. A photo below is of the Marram and Lyme grass vegetation, the dominant grasses, although Piri-piri Burr also present is an invasive species.


The plant pictured below was a puzzle. It is a variety of Cornsalad (Valerianella locusta), growing with Ladies , more ornate than the common winter salad grown in gardens.


Scot’s Lovage (Ligusticum scoticum) growing on the grey dunes is also edible, all parts can be eaten.

scots lovage

The Viper’s Bugloss (Echium vulgare) was strikingly handsome.

Vipers Bugloss.JPG

The lemon yellow flowers of Hop Trefoil (Trifolium campestre) were also unmistakable.

hop trefoil.JPG

Lindisfarne is renowned for its Orchids and Helleborines.  The Northern Marsh-orchid (Dactylorhiza purpurella) has diamond shaped lips and spotted leaves.

Northern Marsh orchid (Dactylorhiza purpurella)

Early Marsh Orchid (Dactylorhiza incarnata) was still flowering in the marshy conditions it prefers, as was the Marsh Pennywort (Hydrocotyle vulgaris) surrounding it.

Early Marsh Orchid (Dactylorhiza incarnata).JPG

This red variety is also Dactylorhiza incarnata, but is a sub species coccinea.

Dactylorhiza incarnata coccinea

Creeping Willow (Salix repens) was abundant and covered with fluffy seeds.

Creeping willow (Salix repens).JPG

It often occurs with Coralroot Orchid (Corallorhiza trifida) shown below.  There was a good showing of spikes of this mostly parasitic plant.

Coral root orchid(Corallorhiza trifida)

This Brookweed (Samolus valerandi) was a plant I had not seen before but was starting to flower.


Heath Milkwort (Polygala serpyllifolia) looked attractive against a backdrop of the greyish lichen Cladonia ciliata and hairy Mouse-Ear Hawkweed leaves.

Heath Milkwort ( Polygala serpyllifolia )

Of deeper colour the Purple Milk Vetch (Astragalus danicus) pictured below is classified as endangered since it has declined in numbers in recent years.

Purple milk vetch (Astragalus danicus)

This pretty  delicate plant with a yellow thrum is Changing Forget-me-not ( Myosotis discolor).

changing Forget me not ( Myosotis discolor ).JPG

Another rarity is the Round Leaved Wintergreen (Pyrola rotundifolia). It was just coming into flower and is noted for its wonderful scent.

Round leaved wintergreen (Pyrola rotundifolia)

As we headed for the Saltmarsh we came across a Bitter Vetch (Lathyrus linifolius).


The saltmarsh was covered in Thrift (Armeria maritima) and flushed with pink.


Samphire (Salicornia europaea) was poking up through the sand like a desert cactus.  Known as glasswort, it is a halophytic annual dicot which grows in various zones of intertidal salt marshes.

Marsh samphire(Salicornia europaea)

These short thin leaves, we thought were of the Eelgrass (Zostera noltii) or Z angustifolia.  Z noltii is intertidal, forming a definite belt between Mean High Water and Mean Low Water. It is the most tolerant of desiccation and is found highest up the shore.
It is rarely found below the low water mark. The bright green species is an Enteromorpha, a major food  plant for the overwintering Brent Geese.


These are just a few of the notable species we encountered in a small part of a small island.




Cullercoats – Rockpools

We spent some time exploring the foreshore area at low tide with a volunteer marine biologist to assist with identification. The picture shows Carboniferous resistant mineralised sandstone ridges lying above the waterline.


Hermit crabs, probably (Pagurus bernhardus) were abundant. The one below was inside a periwinkle shell, others were in larger Dogwhelk shells. The Dogwhelks (Nucella lapillus) likes to hide in tight groups deep in crevices.  They are common on rocky shores.

hermit crab

Sea Lettuce (Ulva latuca) easily found looks like lettuce and is edible.


Corallina officinalis is another common alga. It formed a soft turf with silt on the lower shore.

Corallina officinalis

Its structure of white calcareous segments, is shown below. It was used as a source of calcium carbonate for medicine. Toothed wrack (Fucus serratus) also in the picture covered many of the rocks.


Below is a brown seaweed called False Irish Moss (Mastocarpus stellatus) , distinguished from Irish Moss by channelling in the frond.


We spotted a tiny Amphipod and this Isopod of some kind.


Cladophora rupestris,  pictured below. is  a  densely tufted green algae, that grows up to 20 cm in height, with dark green or bluish coloured dull fronds.  Typically they branch profusely upwards from the base, in an irregular, whorled or opposite pattern. The seaweed had a rough feel.cladophorarupestris

This Chiton (Lepidochitona cinerea) or Coat of Mail Shell, clinging to a Limpet, is probably the commonest and most widespread Chiton found on British rocky shores. Both Limpet and Chiton are Molluscs and graze on micro-algae on the rocks.


Sponges can be difficult to identify. The bright red/pink one could be (Hymeniacedon sanguinea). We also found the Breadcrumb Sponge (Halichondria panicea), olive green, deep inside a crevice.

redspongeBarnacles covered the rocks providing grip for boots amongst the slippery seaweeds. On close up these are (Semibalanus balanoides). The green lichen could be Verrucaria mucosa.

barnaclw lichen

After some searching in crevices Beadlet Anemones were discovered. Actinea equina is a relative of jellyfish. It has stinging cells called nematocysts which it uses to catch prey or for defence.


The group organizer found a Snakelocks Anemone possibly (Anemone sulcata), its purple tipped tentacles are barely visible. Also in the picture a Topshell (Calliostoma zizyphinum) and the tiny coiled up white- shelled (Spirorbis spirorbis).


The sunshine was bright enough to make photography difficult as this last shot of a seaweed fringed pool shows.





The Hamlyn Guide to Seashores and Shallow Seas.