The Beach Below The Spittles 2

Pieces of shale on the beach with holes made by piddocks

After the beach boulders and scattered rusty metal debris, there is sequence of flat rock platforms exposed by the retreating water. They are riddled with holes made by the boring bivalves known as piddocks, some burrows just have empty shells in them but others are still occupied by the living molluscs that squirt water a foot or more into the air at frequent intervals. A velvet swimming crab mooches around the edges of the platforms, and sand tube and mud tube dwelling worms abound on all the surfaces.

Patterns of cracks at Kimmeridge

 

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Natural patterns of cracks in the surface layers of a shale rock platform on the seashore at Kimmeridge Bay in Dorset, England.

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Stone cart tracks and square rock pools at Winspit

Square rockpool at Winspit, Dorset UK - part of the Jurassic Coast (1b) 

This really is a square rock pool. It is one of several to be found on the rock ledge at the foot of the cliffs at Winspit in Dorset. These square pools are scattered amongst the more usual and variously shaped pools on the rock ledge. All the pools are lined with a continuous coating of pink or bleached white calcareous algae. They are fringed with red Coral Weed or green Gutweed and provide a home to an assortment of gastropod molluscs and small fish.

However, the square rock pools are man-made and provide evidence for the industrial history of the area. This is the site of a former quarry. The workings are mostly on the cliff top where you can still explore, with care, the cave like excavations. Large blocks of stone were at one time painstakingly hewn from the strata. The rock was too heavy to cart up the hill to the village. So cranes were constructed from old ships timbers and driftwood  in order to lower the stone from the cliff top to the ‘beach’ below. Another set of cranes was built on the rock platform at the water’s edge to lower the stone into boats. The square pits were carved to hold the base of the main wooden post for these cranes.

Carts were used for transferring the stone from the foot of the cliff to the edge of the ledge. As you might imagine, this could be a bit tricky on a wet and slimy surface. In fact, this operation could only be undertaken in the summer months when conditions were more favourable. The carts were pulled by two men. To stop the carts slipping, over-turning, or going in the wrong direction and into the sea with the hard-earned cargo, two parallel ruts were carved in the rock to accommodate the wheels – a bit like tramlines. Two sets of these cart ruts can still be clearly seen.

Square rockpool at Winspit, Dorset UK - part of the Jurassic Coast (1a) 

View looking east at the cliff and rock platform, Winspit, Dorset, UK - part of the Jurassic Coast (2)

View looking south across the rock platform at Winspit, Dorset, UK - part of the Jurassic Coast (3)

View looking west across the rock platform to the cliffs at Winspit, Dorset, UK - part of the Jurassic Coast (4)

View of ruts carved into the rock platform for hauling carts of quarried stone from cliff face to waiting boats at Winspit, Dorset, UK - part of the Jurassic Coast (5)

Close-up view of cart ruts in the rock platform at Winspit, Dorset, UK - part of the Jurassic Coast (6)

View from west to east across the rock platform at Winspit, Dorset, UK - part of the Jurassic Coast (7)     

Revision of a post first published 15 November 2009

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Japweed at Chapmans Pool

Japweed at Chapmans Pool: Fronds of Japweed, Sargassum muticum (Yendo) Fensholt, washed up on a rock platform at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (1) 

Individual feathery fronds of Japweed can look very decorative when washed ashore and displayed against the natural sediments of the beach. Here this seaweed is shown naturally spread out by the ebbing tide on a flat rock platform at Chapmans Pool. It has a very characteristic appearance and on this occasion the alga is a lovely golden green colour. However, en masse this alien species, Sargassum muticum (Yendo) Fensholt, can constitute a great menace to the environment – as I have detailed in earlier posts.

Frond of Japweed, Sargassum muticum (Yendo) Fensholt, washed up on rocks at Chapmans Pool, Dorset, UK - part of the Jurassic Coast. 

The odd specimen of Japweed ends up artfully arranged by accident among the boulders.

Japweed growing in the sea at Chapmans Pool: Brown patches beneath the surface of the water showing growing beds of Japweed and Thongweed at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (3)

The extensive beds of growing weed are in deeper water of the lower shore. It was not possible to tell which part of this floating brown mass was Japweed and which was Thongweed on my visit as I could not wade out to look (the rock platform is very slippery) but their position is easy to see from afar.

Fronds of Japweed, Sargassum muticum (Yendo) Fensholt, and other seaweeds washed up on the beach at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (4) 

Much of the time, the Japweed is stranded in clumps inter-mixed with other algal types – as shown in the picture below where a bundle of Japweed, Thongweed, Bladder Wrack and assorted red seaweeds lay on the mixed substrate shore of fine gravel, pebbles, and stones on the eastern edge of Chapmans Pool.

Japweed (an accidentally introduced alien seaweed species) washed ashore on the rock platform at Chapmans Pool, Dorset, UK, on the Jurassic Coast World Heritage Site (5) 

 Revision of a post first published 3 July 2009

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Thongweed at Chapmans Pool

Chapmans Pool seaweeds: Thongweed, Himanthalia elongata (Linnaeus) Gray, on the shingle at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (1) 

Thongweed, Himanthalia elongata (Linnaeus) Gray, was washed up in moderate quantities on the shingle at Chapmans Pool in June. This olive green perennial alga belongs to the brown seaweed group – the Phaeophyceae. The part that survives from year to year is small, about 3 cm across and looks like a stalked mushroom with a concave top. It attaches to rocks in deep pools or on the lower shore.

The long narrow ribbon-like part of the weed that is found, sometimes in great abundance, on the shore is in fact the reproductive body which is shed by the seaweed in summer. It may be up to 2m long and turns a more yellow-green colour as it ripens; sometimes with brown spots on it.

These long straps of weed wash up in interesting patterns on the beach sometimes tying itself up into complex knots. Where larger quantities occur, it can roll up into a long sausage shape many metres long parallel to the drift-line.

Chapmans Pool seaweeds: Yellow-green Thongweed reproductive ribbons washed up with Japweed and other weeds on a rock platform at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (2)

Yellow-green Thongweed reproductive ribbons washed up with Japweed and other seaweeds on a rock platform at Chapmans Pool.

Seaweeds at Chapmans Pool: Long narrow straps of Thongweed with Japweed and other algae stranded on a rock platform at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (3)

Long narrow straps of Thongweed with a plume of golden Japweed, bright green Sea Lettuce and assorted red algae on a rock platform at Chapmans Pool.

Floating seaweed at Chapmans Pool: View of Thongweed and Japweed growing in deeper water of the lower shore (visible as an offshore brown 'slick' in the sea) at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (4)

A brown ‘slick’ in deeper water offshore shows where the Japweed and Thongweed are still growing.

In the photograph below, the Thongweed has been washed up in a mass and is drying out on the strandline of a cobble and boulder strewn rocky shore in the southeast part of Chapmans Pool.

Thongweed at Chapmans Pool: Mass of Thongweed drying out on the strandline of the boulder shore in the southeast of Chapmans Pool, Dorset, UK - part of Jurassic Coast (5)

Revision of a post first published 1 July 2009

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Flat or Spiral Wrack from Chapmans Pool

Common British seaweeds picture: An arrangement of Flat or Spiral Wrack, Fucus spiralis L., from Chapman's Pool, Dorset, UK, on the Jurassic Coast World Heritage Site (P1100394aBlog1) 

I’ve talked about Flat or Spiral Wrack (Fucus spiralis Linnaeus) before but wasn’t able to show a good photograph of one of its defining features. Getting close-ups of details on the seashore is sometimes impossible – without lying full-length face-down in wet seaweed. So the last time I was on the beach I collected a few fronds of Flat Wrack, from the extensive beds of Fucoids that covered the flat rock platform on the eastern shore of Chapmans Pool, and took them home to get the photographs that I wanted in comfort.

The pictures above and below illustrate the way that the swollen granular reproductive bodies at the ends of the fronds in this species have a unique flat border – like a seam – around the edge. You can see this border both flat-on and edge-on in the photographs. In other characteristics Flat or Spiral Wrack could be mistaken for another species of Fucoid brown seaweed but it is the only one with this particular characteristic.

Seaweed close-up photograph: Detail of Flat or Spiral Wrack, Fucus spiralis L., from Chapmans Pool, Dorset, UK - part of the Jurassic Coast (P1100402aBlog2) 

The rock platform on the eastern edge of Chapmans Pool in June was covered in an olive green carpet of short Fucoid seaweeds including, Toothed Wrack, Bladder Wrack, and Flat or Spiral Wrack.

Seaweeds photograph: View of the seashore at Chapman's Pool with a rock platform covered with Flat Wrack and other Fucoid seaweeds, in Dorset, UK, on the Jurassic Coast World Heritage Site (P1100262aBlog3) 

You have to look closely to see that the seaweed bed is composed of all the different types of weed, growing together, and overlapping each other in a complex natural mosaic pattern.

Picture of seaweeds: Closer view of Flat Wrack and other Fucoid seaweeds on a rock platform at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (P1100259aBlog4) 

In the picture below you can see the round pea-shaped air bladders that occur in Bladder Wrack. There are fronds like this on the left side of the picture. The golden yellow-green reproductive bodies on the forked tips of the Flat Wrack are quite distinct elsewhere in the photograph. Both seaweeds have a central midrib along the fronds. 

Previously, Flat or Spiral Wrack was discussed in the earlier post Three brown seaweeds: Furbelows, Sea Belt & Spiral Wrack from Studland Bay in spring.

Seaweeds close-up photograph: Detail of Flat Wrack and other Fucoid seaweeds on a rock platform at Chapmans Pool, Dorset, UK - part of the Jurassic Coast (P1100264aBlog5) 

Revision of a post first published 5 June 2010

COPYRIGHT JESSICA WINDER 2011

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Rock pavement at Kimmeridge Bay

P1050977aBlog1 Yellow rock pavement at Kimmeridge Bay, Dorset, UK on the Jurassic Coast World Heritage Site 

Rock platforms, pavements or ledges are a most fascinating feature of the beach at Kimmeridge Bay in Dorset. The cliffs are made up of alternating layers of various mudstones and bituminous shales making up the Kimmeridge Clay sequence. The ledges are seaward projections of the harder limestone rock layers that arise from the base of the cliffs. They are dolomitic limestone which is basically dark grey but when it contains a higher proportions of iron it is yellowy.

The ledges and platforms are covered with cracks and crevices forming interesting geometric shapes. Viewed from above, a larger pattern of shapes, termed megapolygons, is visible. I do not fully understand the processes that underlie the creation of these natural designs. I think the tremendous pressure of what was once a kilometre deep layer of sedimenatry rocks above this stratum, and crystallisation within the sediments of this particular layer, may have been contributary factors.

Whatever the cause of them, the patterns are intriguing; and I will show more photographs of them in later Posts. The smooth flat surfaces and the crevices of the ledges and pavements provide substrates on which seashore animals and plants can settle and shelter – thus contributing to the fantastic array of wildlife that occurs at Kimmeridge in this marine wildlife reserve.

For more information about the geology of Kimmeridge Bay see the most excellent academic guide written by Ian West of the National Oceanography Centre in Southampton University.

For more information about Kimmeridge Bay and its wildlife you can refer to the Purbeck Marine Wildlife Reserve Web Site.

P1060201aBlog2 Grey rock pavement on the shore at Kimmeridge Bay, Dorset, UK - part of the Jurassic Coast World Heritage Site 

COPYRIGHT JESSICA WINDER 2011

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