Winspit Waves 4

  

CLICK ON THE IMAGE FOR A SHORT VIDEO OF WAVES AND REFLECTION PATTERNS

Waves washing onto a seashore rock ledge, with dynamic patterns of reflected light each time the water retreats. 

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Winspit Waves 3

Waves breaking on the rock ledge at Winspit, Dorset, UK, on the Jurassic Coast

Waves breaking on the rock ledge at Winspit, Dorset, UK, on the Jurassic Coast where stone was quarried from the cliffs in times gone by and loaded onto boats.

CLICK ON THE IMAGE BELOW FOR A SHORT VIDEO OF THE WAVES

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Winspit Waves 2

The waves breaking on the man-made rock ledge at Winspit, Dorset, UK on the Jurassic Coast.

The waves breaking on the man-made rock ledge at Winspit, Dorset, UK on the Jurassic Coast, where stone was quarried long ago and loaded straight onto boats.

CLICK ON THE IMAGE BELOW FOR A SHORT VIDEO OF THE WAVES

COPYRIGHT JESSICA WINDER 2011

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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

COPYRIGHT JESSICA WINDER 2011

All Rights Reserved 

Trace fossils in Winspit rocks

Trace fossil burrows in a limestone boulder, made by marine invertebrate creatures in ancient times, at Winspit, Dorset, UK - part of the Jurassic Coast (1)

Trace fossils are geological records of biological activity. The rocks at Winspit in Dorset have preserved evidence of the burrowing habits of invertebrate animals that once lived in the soft wet sediments on the seabed and seashore of shallow seas over 135 million years ago in the Upper Jurassic period.

These trace fossils include burrows and tunnels made by crabs and worms. In some instances, the holes made by the creatures remain visible – as pictured in the first three photographs below. They look remarkably similar to the holes made by boring bivalved molluscs and by mud-tube dwelling marine polychaetes that occur in present day calcareous stones and mollusc shells (see the earlier posts on these subjects). As I am not a palaeontologist, I concede that this may not actually be a parallel causation – just a coincidence.

General view of the trace fossil bearing boulders where the valley meets the sea at Winspit, Dorset, UK - part of the Jurassic Coast (2) 

Trace fossils in a limestone boulder at Winspit, Dorset, UK - part of the Jurassic Coast (3)

Close-up of trace fossils shown in Photos 2 & 3, limestone boulder at Winspit, Dorset, UK - part of the Jurassic Coast (4) 

In most of the examples illustrated by the photographs below, the spaces enclosed by the burrows have been infilled by other sediments so that instead of the original hollow tubes and tunnels remaining in the hardened rock, the burrows have become roughly cylindrical solids. The infill substance seems to be harder than the matrix surrounding it. This means that the softer rock has  weathered more readily and the burrows stand out like cords.

Limestone boulder with trace fossils at Winspit, Dorset, UK - part of the Jurassic Coast (5) 

A pile of large angular boulders, between one and two metres across, rests on the rocky ledge at the foot of the cliffs where the valley meets the sea at Winspit. On the flat surfaces of some of the rocks are intricate patterns made up of  horizontally branching networks of solid tubes about a centimetres or so in diameter. These are similar to the burrows made by decapod crustaceans (crabs) called Thalassinoides

Close-up of trace fossils in limestone boulder (shown in photo 5) at Winspit, Dorset, UK - part of the Jurassic Coast (6) 

Large Titanites giganteus ammonite fossil in a limestone boulder at Winspit, Dorset, UK - part of the Jurassic Coast (7) 

Large fossilised remains are found in these strata as well as the trace fossils. One of the best known, because of its large size, is the ammonite Titanites giganteus as shown in the picture above. It is about 40 centimetres in diameter. Although well embedded in the massive boulder, and a feature of the location for as long as anyone remembers, someone has recently tried unsuccessfully to hack it out of the rock. It is a shame because it has left the wonderful fossil damaged and defaced. 

Trace fossils on the surface of a large limestone boulder (with walking pole for scale), Winspit, Dorset, UK - part of the Jurassic Coast (8) 

Detail of trace fossils on limestone boulder (photo 8) at Winspit, Dorset, UK - part of Jurassic Coast (9) 

Detail of trace fossils on limestone boulder (photo 8) at Winspit, Dorset, UK - part of Jurassic Coast (10) 

Trace fossils on a limestone boulder at Winspit, Dorset, UK - part of the Jurassic Coast (11) 

Detail of trace fossils in a limestone boulder (photo 11) at Winspit, Dorset, UK - part of the Jurassic Coast (12) 

Detail of trace fossils in a limestone boulder (photo 11) at Winspit, Dorset, UK - part of the Jurassic Coast (13) 

Limestone boulder with surface covered in trace fossils at Winspit, Dorset, UK - part of the Jurassic Coast (14) 

Some of the burrows, particularly the larger ones that may have been made by crabs, seem from these trace fossils to have passed through a series of layers in the sediments. Sediments from different layers are mixed up, and older sediments brought to the surface and deposited above more recent ones, as animals excavate their tunnels. This process is called bioturbation. Geologists, palaeontologists, and archaeologists are all aware of the implications of bioturbation for the interpretation of results from their research and excavations. 

Another name for trace fossil is ichnofossil. To read some more about ichnofossils click here.

Detail of trace fossils on a limestone boulder (photo 14) at Winspit, Dorset, UK - part of the Jurassic Coast (15) 

Revision of a post first published 9 December 2009

COPYRIGHT JESSICA WINDER 2011

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Winspit Waves 1

Sparkling waves seen from the rock ledge on the shore at Winspit, Dorset, UK, on the Jurassic Coast - site of ancient quarrying activities.

Sparkling waves breaking on the rock ledge of the shore at Winspit, Dorset, UK, on the Jurassic Coast – site of ancient quarrying activities.

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Tiny gastropods & pitted barnacles at Winspit

Tiny black smooth-shelled gastropod molluscs, Melarhaphe (Littorina) neritoides Linnaeus, clustered amongst acorn barnacles, on the rocky shore at Winspit, Dorset, UK - part of the Jurassic Coast (1)

If you get on your hands and knees to peer closely at the acorn barnacles high up on rocky shores, especially in the splash zone, you may be surprised to see tiny gastropod molluscs on them, between them, and even sheltering inside their empty cases. Some of these molluscs look like smooth, dark grey grape pips. They are Small Periwinkles, Melarhaphe neritoides Linnaeus, formerly known as Littorina neritoides.

Small Periwinkle shells have a flat-sided spire and pointed apex. The main shell body whorl is black or brown but the colour is variable and light-hued specimens do occur. The surface of the shell is generally smooth but the body whorl may have spiral banding or vertical stripes. The whole shell measures no more than 9mm high by 7mm across and many are a lot smaller. These seashore creatures feed on detritus and black lichen. Black lichen can grow in very small patches on barnacle shells or as more extensive areas on the rocks. At Winspit in Dorset where these photographs were taken, the appearance of the barnacle shells has been altered by the presence of endo-lithic lichens so that they have many pits and lace-like sculpturings. The pits are the place where the fungus part of the lichen produces spores. It is possible to see these as small black dots in some of the pits.

You can read more about this endolithic lichen and pitted barnacle shells in an earlier post: Pitted barnacle shells at Bran Point.

Also present in these photographs is the larger Rough Periwinkle – Littorina saxatilis (Olivi) - which tends to be yellow and is covered with sharp spiral ridges. You can read more about Rough Periwinkles in an earlier post: Rough Periwinkles at Kimmeridge Bay

Small Periwinkles and Rough Periwinkles grazing amongst lichen-pitted acorn barnacles, on the upper rocky shore at Winspit, Dorset, UK - part of the Jurassic Coast (2)

Upper rock shore habitat for lichen, sessile barnacles, Small Periwinkles and Rough Periwinkles at Winspit, Dorset, UK - part of the Jurassic Coast (3) 

Revision of a post first published 17 December 2009

COPYRIGHT JESSICA WINDER 2011

All Rights Reserved