Case Study Site 3 – The Isle of Purbeck, Dorset

Case Study Site 3 – The Isle of Purbeck, Dorset

1.         Location

The case study covers the coastline of the Isle of Purbeck, extending from Handfast Point, southwards through Swanage Bay to Anvil Point, and westwards as far as St Aldhelm’s Head. 

2.         Why was the Case Study Site selected?

The site was selected because of its diverse range of coastal management and heritage issues, which are well illustrated by artworks from the nineteenth and early twentieth centuries. They offer the opportunity to evaluate accuracy through comparison with present day photographs.  The images show the effects of time on heritage structures such as Swanage Pier as well as illustrating the quarrying heritage sites along the coast of the Isle of Purbeck. 

3.         Summary of the Geology, Geomorphology & Coastal Processes

The geology is characterised by strata running east to west across the Isle of Purbeck, with the Chalk to the north and the underlying sands and clays of the Lower Greensand and Wealden Groups outcropping in Swanage Bay.  The headlands of Pebble Point and south to Durlston are formed in the Purbeck Group of limestones and mudstones, which were quarried extensively in the past for their high quality building stone. 

The eroding cliffs in Durlston Bay and the northern part of Swanage Bay contribute sediments to the overall system (Figures 3.1 and 3.2).  The general trend is for sediment to move from south to north along the coastline, although there is a north/south movement further out to sea, extending from Handfast Point southwards.  Historical rates of erosion along this frontage range from 0.3 to 0.7m per annum, and there are several locations where there have been coastal landslides and rock falls, the narrow foreshore being strewn with boulders and smaller debris along the toes of the clifflines (Royal Haskoning, 20111). 

Figure 3.1: ‘The Fine Sweep of Swanage Bay’, a watercolour, c.1915 by Ernest William Haslehust.  The view looks south towards the headland of Ballard Point.  The growing resort of Swanage can be seen in the centre of the Bay. 

Image Courtesy: Private Collection

Figure 3.2:  A close view of ‘The Sands, Swanage’ showing the seafront and cliff top architecture.  This watercolour was painted by Alfred Robert Quinton in about 1912.

Image Courtesy of J. Salmon Limited of Sevenoaks. 

4.         Risks to Heritage Assets along the Case Study Frontage

The town of Swanage and its Conservation Area will continue to be defended in the future, although the coastlines to the north, up to Handfast Point, and Durlston Bay to the south, and the coastline westwards to St Aldhelm’s Head have a policy of ‘no active intervention’ (Royal Haskoning, 20111). 

In Swanage, the present pier, which replaced an earlier structure, required significant investment to maintain its integrity and this was completed recently as an award-winning scheme.  Along the coastline to the south of Swanage, between Durlston Head and Anvil Point, two pairs of towers mark the extent of a ‘nautical measured mile’.  These towers enabled various ships to be timed over that distance. 

The south coast of the Isle of Purbeck is particularly important for its quarrying heritage (Stanier, 19962).  The Jurassic limestones of the Purbeck Beds have been quarried since Roman times, whilst the Portland Series which underlie them were formerly worked along the coastal cliffs from St Aldhelm’s Head to Durlston Head.  A range of heritage features including rutways, sites of cranes and tramways, and other evidence of the quarrying industry are widespread.

At Emmet’s Hill near Worth Maltravers the bowl barrow is a Scheduled Monument (List Entry Number: 1017268) and the site is at risk from coastal erosion. At St Aldhelm’s Head the ancient Chapel is close to the sea cliff and could be lost eventually unless, at some time in the future, the structure is re-located further inland. Continued rates of erosion over the next 100 years, estimated at between 0.5 and 0.7m per annum, are likely to see the loss of some of these features as a result of episodic cliff failure events. 

5.         How can historical Imagery inform heritage risk management?

Early twentieth century postcards illustrated by the watercolour artists Henry Wimbush and Alfred Robert Quinton depict the coastal resort of Swanage in some detail; Swanage Pier is also featured (Figures 3.3 and 3.4).

The quarrying industry and the major headlands including Handfast Point, Peverill Point, Tilly Whim Caves at Durlston Head and St Aldhelm’s Head were engraved with views being published in important works such as Sir Henry Englefield’s ‘Geology and Antiquities of the Isle of Wight and the adjacent coast of Dorsetshire’ (Englefield, 18163) – see Figures 3.5 to 3.8.  Comparison of coastal artworks by artists such as Alfred Robert Quinton, a prolific Edwardian painter of coastal views, with recent photographs allow evaluation to be made of change of the reliability of art to inform us of the rate of change to coastal cliff lines over the last 200 years. 

Figure 3.5: ‘Map of the Isle of Purbeck’ from Sir H. Englefield’s ‘Geology and Antiquities of the IW & Dorsetshire’ (1816).  St Aldhelm’s Chapel is marked (bottom left).

Figure 3.6: ‘St Aldhelm’s Chapel’ by Thomas Webster (1816) is located close to the cliff edge at St Aldhelm’s Head.  Englefield (1816) said “Not many yards from the edge of the precipice stands the Chapel.  The upper cliff is composed of immense fissures many of which are ready to fall.  The whole of the base (of the cliff) is covered with vast blocks that have tumbled down and show how much of the headland has been destroyed by the furious sea to which it is exposed.”

Figure 3.7: The distorted limestone formations at ‘Durlston Head’ are illustrated in this drawing by T. Webster, which was engraved by George Cooke in 1816.

Figure 3.8: ‘Tilly Whim Quarry’ drawn by Thomas Webster in 1816 illustrates work in progress at this site.  Webster’s detailed geological depictions of the Dorset coast, which he produced for Sir H. Englefield, provide a complete record of conditions here in the early nineteenth century.  Because Englefield was a scientist and antiquarian with a fascination for geology, he was only interested in topographical accuracy rather than creating a ‘picturesque landscape’. 

Figure 3.9: ‘The Quarries’ were also painted by A. R. Quinton, c.1920 and show little change from Webster’s drawing a century before.  One of the ‘Measured Mile’ posts can be seen on the hillside to the left with Durlston Castle beyond.

Image Courtesy of J. Salmon Limited of Sevenoaks.

Figure 3.10: This present day view of Tilly Whim Caves compares very closely with Quinton’s watercolour (above), including details of the jointing in the limestone. 

Image Courtesy of Andy Jamieson under Creative Commons Licence.

Figures 3.11 and 3.12 offer comparisons between artworks and photography and illustrate the topographical accuracy of artists such as A. R. Quinton.  This view of Peveril Point near Swanage was painted c.1920. 

Image Courtesy of J. Salmon Limited of Sevenoaks.

Photograph (above) Courtesy of Jim Champion, Creative Commons Licence.

Figures 3.13 and 3.14 again compare A. R. Quinton’s coastal artworks with photography.  Although Quinton’s view is closer to Anvil Point and the Lighthouse, the detail he has achieved in his scene is very striking. 

Image Courtesy of J. Salmon Limited of Sevenoaks.

Photograph Courtesy of Chris Downer, Creative Commons Licence.

6.         Key Issues – What can be learnt from this site?

The images describe the changing face of the popular seaside town of Swanage and its pier, as well as illustrating the cliff top heritage features including St Aldhelm’s Chapel and the measure mile posts. The whole of this coastline has been engraved by numerous artists including W. B. Cooke and Sir Henry Englefield.

7.         References

  1. Royal Haskoning and Bournemouth Borough Council, 2011. ‘Poole and Christchurch Bays SMP2’.
  2. Stanier, P., 1996. ‘The Quarried Face: Evidence from Dorset’s Cliffstone Quarries’. Historical Metallurgy Society Special Publication: The Archaeology of Mining and Metallurgy in South-West Britain.
  3. Englefield, Sir H., 1816.  ‘Geology and Antiquities of the Isle of Wight and the adjacent coast of Dorsetshire’.