DORSET BUILDING STONE
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Broken Shell Limestone (BSL), also known as Burr (lead authors JT/WGT)

The Purbeck Group comprises the Lulworth Formation (three Members) overlain by the Durlston Formation  (two Members).   The Broken Shell Limestone Bed (aka Burr) lies at the base of the upper member of the Durlston FM, the Peveril Point Member  (Early Cretaceous, Berriasian).  The Purbeck Marble lies a little above.   The Purbeck Group was deposited over a period of some 6 million years (146-140my).
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The BSL has a distinctive texture resulting from dissolution of small bivalve shells, leaving densely packed shell moulds cemented by sparite.
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The BSL has been quarried on the lower part of the steep north-facing slope of the Purbeck anticline, where the beds are folded so tightly that the outcrop is located on the hill above the Marble quarries dug by the Romans.  The outcrop of both Marbles and BSL runs from Peveril Point through the valley to Worbarrow Tout, and both would have been quarried at least from Norman times onwards.
At Crack Lane (a quarry near Swanage opened in the late 19th century and working until 1960) the Broken Shell Limestone can be seen to be in several thick beds suitable for cutting as ashlar.  The lowest 2 metres are of massive, cream-coloured stone, consisting of the broken bivalve shells (Neomiodon, Unio).  The shell debris is disturbed, as if by storm action in shallow water. The middle section in Crack Lane is again nearly 2 metres of thinner beds, often cross-bedded, with the same shell debris, and an upper section is 2 metres of massive stone. The shell debris is cemented with sparite (crystalline calcite), which makes it a strong and weight-bearing stone.   Crack Lane is one of five quarries in the Isle of Purbeck that have been designated as Regionally Important Geological Sites (RIGS), and the DIGS group has prepared an illustrative CD which was funded by Purbeck District Council’s Purbeck Keystone Project in 2009. This CD may be purchased from DIGS, through the Dorset Wildlife Trust.
Burr vs. Quarr 
Despite being about 110 million years older, Burr is similar in appearance to the Eocene -Oligocene Quarr Stone of the Bembridge Limestones (Isle of Wight)  and it is often hard to decide between them when examining a weathered building block encrusted with fungal/algal  growth. Both are mouldic bivalve biosparite grainstones.  This table may assist. (see right)
Text JT/WGT March 2017
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© DORSET BUILDING STONE
and contributors
  • Home
    • About Us
    • Glossary
    • References and Sources
    • Work in Progress
  • Building stones
    • How we study building stones
    • Palaeogene >
      • Heathstone
      • Sarsens
    • Cretaceous >
      • Chalk
      • Flint
      • Upper Greensand
      • Chert
      • Wealden
      • Purbeck >
        • Upper Purbeck (Purbeck Marble)
        • Upper Purbeck (Broken Shell Lst. aka Burr)
        • Middle Purbeck (Upper Building Stones)
        • Lower Purbeck (Cypris Freestones)
    • Jurassic >
      • Lower Purbeck >
        • Cypris Freestones
      • Portland Stone - Dorset
      • Chert
      • Kimmeridge Bay Dolomitic Limestone
      • Corallian
      • Cornbrash
      • Forest Marble
      • Fuller's Earth Rock
      • Inferior Oolite
      • Bridport Sands
      • Junction Bed
      • Blue Lias
    • Dorset Bricks
    • Non-Dorset Stone >
      • Tertiary >
        • Bembridge Limestones - Isle Of Wight
      • Cretaceous >
        • Beer Stone - SE Devon
      • Jurassic >
        • Bath Stone - Somerset & Wilts
        • Blue Lias of Somerset
        • Doulting Stone - Somerset
        • Ham Hill Stone - Somerset
        • Portland Limestone – Wilts (Chilmark)
        • Normandy >
          • Pierre de Caen (Caen Stone)
        • Pas de Calais
      • Triassic: White Lias of SE Devon
      • Carboniferous >
        • Carboniferous Limestones: Polished Black
      • Devonian
    • Building Stone Trails >
      • Devon Trails
      • Somerset Trails
    • Stone Index >
      • Stone Index A-B >
        • Abbotsbury Ironstone
        • Bath Stone
        • Beer Stone
        • Bembridge Stone
        • Binstead Stone
        • Blue Lias Stone
        • Bridport Sandstone
        • Broken Shell Limestone
        • Burr
        • Burton Limestone
      • Stone Index C-E >
        • Caen Stone
        • Carstone
        • Chert
        • Chilmark Lower Building Stone
        • Chilmark Main Building Stone
        • Chilmark Stone
        • Chilmark Upper Buiding Stone
        • Clavellata Beds
        • Cliff Stone
        • Clunch
        • Corallian
        • Cornbrash
        • Cypris Freestone
      • Stone Index F-O >
        • Featherbed Limestone
        • Featherstone
        • Forest Marble
        • Flint
        • Fuller's Earth Rock
        • Grey Chalk
        • Ham Hill Stone
        • Heathstone
        • Inferior Oolite
        • Ironstone
        • Lower Chalk
        • Lower Lias
        • Melbury Sandstone
        • Middle Chalk
        • Middle Lias
        • New Vein
        • Osmington Oolite
      • Stone Index P-T >
        • Portland Cherty Beds
        • Portland Cherty Series
        • Portland Stone
        • Purbeck Marble
        • Purbeck Stone
        • Quarr Stone
        • Rag
        • Sarsen Stone
        • Shaftesbury Sandstone
        • Sherborne Stone
        • Tisbury Stone
        • Todber Freestone
        • Trigonia Beds
      • Stone Index U-Z >
        • Upper Chalk
        • Wardour Lower Building Stone
        • Wardour Main Building Stone
        • Weald Clay
        • White Chalk
        • White Lias
        • Yeovil Stone
  • Churches
    • A-Z of Churches
    • East Dorset >
      • Almer
      • Bournemouth >
        • Talbot Village
      • Canford Magna Chapel
      • Corfe Mullen
      • Christchurch Priory
      • Cranborne
      • Edmondsham
      • Gussage All Saints
      • Gussage St. Andrew
      • Hampreston
      • Kinson
      • Knowlton
      • Morden
      • Pamphill
      • Poole St.James
      • Poole, the Spire Church
      • Shapwick
      • Sturminster Marshall
      • Tarrant Crawford
      • Tarrant Keyneston
      • West Parley
      • Wimborne St.Giles
      • Wimborne Minster Exterior Tour
      • Wimborne Minster Interior
      • Wimborne Minster: Purbeck Marble and Decorative Stone
    • Central Dorset >
      • Bloxworth
      • Bradford Peverell
      • Cerne Abbas
      • Hilton
      • Lytchett Matravers
      • Stratton
      • The Piddle Valley >
        • Affpuddle
        • Alton Pancras
        • Bere Regis
        • Piddlehinton
        • Piddletrenthide
        • Puddletown
        • Tolpuddle
      • Winterborne Tomson
    • North Dorset >
      • Batcombe
      • Belchalwell
      • Blandford Parish Church
      • Blandford St. Leonard's Chapel
      • Blandford St. Mary
      • Blandford Cemetery Chapels
      • Bradford Abbas
      • Chetnole
      • Child Okeford
      • Compton Abbas
      • Farnham
      • Folke
      • Gillingham
      • Hammoon
      • Hazelbury Bryan
      • Holnest
      • Ibberton
      • Iwerne Minster
      • Langton Long
      • Leigh
      • Mappowder
      • Margaret Marsh
      • Marnhull
      • Melbury Abbas
      • Melbury Bubb
      • Pimperne
      • Okeford Fitzpaine
      • Purse Caundle
      • Ryme Intrinseca
      • Shillingstone
      • Sixpenny Handley
      • Stockwood
      • Stourpaine
      • Tarrant Gunville
      • Tarrant Hinton
      • Tarrant Monkton
      • Tarrant Rushton
      • Todber
      • Winterborne Stickland
      • Winterborne Zelston
      • Woolland
      • Yetminster
    • South Dorset >
      • Abbotsbury
      • Bindon Abbey
      • Church Knowle
      • Coombe Keynes
      • East Holme
      • Kingston
      • Martinstown
      • Moreton
      • Portesham
      • Portland: Reforne
      • Steeple
      • Stinsford
      • Studland
      • Swanage
      • Upwey
      • Wareham St. Martin-on-the Walls
      • Wareham St.Mary >
        • St. Martin's-on-the-walls
      • Winterborne Came
      • Winterborne Steepleton
      • Wool
      • Worth Matravers
    • West Dorset >
      • Beaminster
      • Bothenhampton
      • Bradpole
      • Bridport
      • Broadwindsor
      • Burton Bradstock
      • Burstock
      • Catherston Leweston
      • Chelborough
      • Evershot
      • Eype
      • Loders
      • Monkton Wyld
      • Netherbury
      • North Poorton
      • Powerstock
      • St. Gabriel’s
      • Shipton Gorge
      • Lulworth Castle
      • Stoke Abbott
      • Symondsbury
      • Wootton Fitzpaine
      • Whitchurch Canonicorum
  • Quarries , Pits and Limekilns
    • Active Quarries
    • Abbotsbury area
    • Beacon Limestone Quarries
    • Inferior Oolite
    • North Dorset Corallian
    • Kimmeridge Bay
    • Portesham
    • Portland near Swanage
    • Purbeck near Swanage
    • Shaftesbury Sandstone
    • Uplyme Quarries
    • Upwey
    • Whiteway Hill Quarry
    • Winspit Quarry
    • Non-Dorset Quarries and Pits
  • Secular buildings
    • Athelhampton House
    • Blandford Town Hall
    • Cerne Abbas (village and Abbey)
    • Durweston Bridge
    • Ibberton Village
    • Kimmeridge Bay
    • Moignes Court
    • Non-Dorset Buildings
  • Search
  • Contact Us