Lulworth Castle (lead authors: GR and GT)

Lulworth Castle. Photo: GR

The much remodelled interior has Portland Freestone, Purbeck Limestone, Chalk, dark Heathstone, as well as brickwork.​​
All the images below are GR and show the castle's interior.

Text and images by GR: March 2017

Lulworth Castle – Building Stones and Sources

 Lulworth Castle was built as a hunting lodge circa 1608. It was remodelled 1609-11 and remodelled again in 1641. There is Portland Freestone ashlar stone to the main front, with the remainder of Purbeck Limestone rubble stone with some Heathstone. The building is effectively just a shell having been gutted by fire in 1929, but it does make the interior stonework very visible. The central block is brick. It has a square plan, with circular comer towers, in pseudo-military style. There are three storeys and a basement -with the towers four-storeyed. The main east front has a raised terrace with stone steps and a balustrade. It has a round-headed doorway, flanked by a twin portico with Ionic columns and entablatures. There are small circular windows on each side. There is a circular traceried window over the door.

The informal “Dorset Building Stones group” visited Lulworth Castle on Monday 24th July 2017, escorted by David Greenhalf of Lulworth Estates.  He sought the group’s views on:-
    1) The columns at the front (1660-69)
    2) The ashlar (front)
    3) The rubble walls (sides/rear)
 This summarises the opinions of the visitors (additional photos are attached)

The columns at the front (and one in the basement) are Upper Jurassic Portland Limestone from the Isle of Portland, based on fossil content (red alga Solenopora fragments) and bed thickness.  The columns are understood to date from 1660-69.  Stone was exported from the Isle of Portland for the Queen’s House at Greenwich 1616-40 and the detailing of the Whitehall Banqueting House 1619-22, so the 1660-69 date is compatible with this source.  The steps are also Portland Stone with large fossil bivalves. 
The ashlar on the east front is a mixture of bioclastic, oolitic and micritic Portland Limestones and a wide range of Upper Jurassic to Lower Cretaceous Purbeck Limestones: Lower Purbeck algal Caps and laminated Cypris Freestone; Middle Purbeck Downs Vein and Pond Freestone; Upper Purbeck Burr (aka Broken Shell Limestone, BSL) and micritic beds from the Upper Cypris Clays and Shales.  The source is not proven but it is speculated to have been the coastal Portland-Purbeck outcrop of the Lulworth Cove to Warbarrow Tout area, landed by boat at Arish Mell.  The later remedial ashlar is from the Isle of Portland. 
The rubble walls comprise the same wide range of building stone as the ashlar, with the addition of some Eocene Heathstone (ferruginous sandstone, as in the Church tower plinth), Upper Cretaceous Flint & possible recycled masonry, all of which could be sourced locally.  Internally, there is Upper Cretaceous Chalk and some large flint.  The bedrock of Lulworth Castle is Eocene ferruginous sandstones but Chalk with a superficial cover of “clay with flints” outcrops within the estate.

Observations by:
Treleven Haysom D.Tech – Stone mason, quarry owner, conservation advisor
Paul Ensom – Purbeck Stone geologist (e.g. Purbeck Beds of Bacon Hole 2010)
Dr Geoff Townson C.Geol.FGS – Portland Stone geologist (DPhil Portland Beds 1971)
Pat Snelgrove – Author of Virtual Field Trips to Isle of Purbeck (CD)
Sheila Alderman – Member Open Univ Geol Soc & Dorset Geol Assoc Group
Jo Thomas – Author of Dorset Stone (2008)
Peter Bath – Building stone petrographer & microscopist

WGT July 2017