30-35 SECONDS PER SLIDE THE GREENSAND COUNTRY: SANDSTONE STRUCTURES Presentation to Diocese of St. Alban: Church Architects + Surveyors Summer Workshop COMPOSITION 06 INTRODUCTION (TITLE PAGE) 01 Quartz (silica) particles = 0.07-2.0mm Most particles unconsolidated or weakly bound TALK … much of rock is sand = useful only as an aggregated About how sandstone plays a part in the character of the Greensand Country 02 Some horizons towards upper levels Going to deal with: …. tightly bound with more quartz and iron oxides = can yield a reasonable building • PROPERTIES OF THE STONE stone • SOURCES …. Albeit discontinuous and irregular • HISTORIC USAGE GENERALLY • ITS USE IN MINOR SANDSTONE STRUCTURES, MAINLY WALLS Highly variable stone = careful selection … ending with an overview of how such structures are vulnerable to loss, etc. DURABILITY 07 … hence providing context for Claire to talk in more detail about …. Cemented BACKGROUND • HIGH PERCENTAGE QUARTZ = HARD & DURABLE • HIGH IRON OXIDE = FRIABLE & PRONE TO EROSION Based on AUDIT of minor sandstone structures + their context carried out in 2015 Harder stones for building; more friable for boundary walls, etc. … one of a number of studies that fed into Landscape Conservation Action Plan Bedding … general comment … its aim being to: • DETERMINES MAXIMUM SIZE OF STONE & WAY IT IS USED • INCREASE UNDERSTANDING OF THE ROLE PLAYED BY MINOR SANDSTONE STRUCTURES & THEIR CONTEXT IN THE DISTINCTIVE CHARACTER OF THE COLOUR 08 GREENSAND LANDSCAPE. • Regardless of how the rock is cemented …. iron rich compound IDENTIFY HOW SURVIVAL IS THREATENED • PROVIDE IN A RESPONSE A CONSERVATION STRATEGY … adds up to a range of colours: Rusty ochre – brown Limitations Ironstone • DID NOT DEAL WITH MINOR GARDEN FEATURES • GENERIC TERM FOR MANY IRON-RICH STONES • COVERED THE WHOLE OF THE GREENSAND AREA + KILOMETRE BUFFER • INCLUDING LIMESTONES = SHENLEY HILL • EXCLUDED THE URBAN AREAS OF LEIGHTON BUZZARD + LINSLADE • NOT TO DENIGRATE LOOSE USAGE OF THE TERM Other minerals METHODOLOGY • GLAUCONITE = IRON-POTASSIUM SILICATE Literature review 03 • HUSBORNE CRAWLEY CHURCH Field survey 04 • UPPER AND LOWER GREENSAND CONFUSION Analysis WORKABILITY 09 Usable stone is not a freestone despite small particle size PROPERTIES … WHAT ARE WE TALKING ABOUT? • DIFFICULT TO CARVE GEOLOGY 05 • RARELY USED FOR MOULDINGS OR COMPLEX DETAILS • CANNOT BE WORKED AS ASHLAR Underlying 120 metre thick layer of sedimentary rock • DISTINCTION BETWEEN ROCK AND STONE Always used as Rubble • RANDOM & SQUARED; SOMETIMES COURSED Laid down 110 to 125 million years ago Often combined with other materials 10 Generally hidden by layers of clay and other soils • TOTTERNHOE STONE; PEBBLES, RIVER COBBLES (IVEL), ETC. Historically known as the Lower Greensand … … though more correctly the WOBURN SANDS FORMATION Page 1 of 3
30-35 SECONDS PER SLIDE THE GREENSAND COUNTRY: SANDSTONE STRUCTURES Presentation to Diocese of St. Alban: Church Architects + Surveyors Summer Workshop OTHERWISE … IN TERMS OF OCCUPIED BUILDINGS 18 SOURCES … WHERE DID IT COME FROM? Some early cottages QUARRIES 11 • CLOPHILL (STONE JUG) & POTSGROVE Some identified on Strategic Stone Study New churches • DOES NOT YET COVER BUCKINGHAMSHIRE OR CAMBRIDGESHIRE • SILSOE (1829-31); CLOPHILL (1848-9); LIDDLINGTON (1886) Old maps … 12 4 x schools … sand and stone pits; quarries; interchangeable • POTSGROVE (1897-8), ASPLEY GUISE (1847-50), STEPPINGLEY (1877-8) ; POTTON (1896-8) DELVES 13 Lodges to parkland Cannot use used – Planning Permission, etc. • WOBURN, WREST, HAYNES PARK, SOUTHILL & HAZELLS Other buildings CURRENT SUPPLIES SUTTON PARK HOUSE (1858) NOW JOHN O’GAUNT GOLF CLUB 19 • All mainly aggregate, often on massive scale NEW SPRING PUMPING STATION, ENGINE HOUSE & PUMP MASTER’S HO. (1906) 20 • Two known to provide dimensioned stone • CAINHOE + HEATH & REACH SUMMARY 21 Reference to APPENDIX C OF REPORT In all, less than 50 occupied sandstone buildings in or near the Greensand Country This is compared to 43 churches that are in whole or in part sandstone … 22 USAGE … HISTORY … including further afield there are 71 sandstone churches + chapels CHURCHES 14 Churches aside, the contribution of sandstone to the character and identity of the Greensand Country = clusters of MINOR STRUCTURES, primarily walls. 23 Many of medieval foundation … … but little medieval stone, at least externally. MINOR SANDSTONE STRUCTURES 19th (some 20th) century … TYPOLOGY … restoration • Walls but also: MILLBROOK (1857-8); LITTLE BRICKHILL (1864-5); HUSBORNE CRAWLEY (1911) UNOCCUPIED FARM BUILDINGS 24 • … rebuilding • BRIDGES 25 STEPPINGLEY (1858-60); MAULDEN (1858-9) • MISCELLANEOUS 26 Externally, some survival • • TOWERS: HUSBORNE CRAWLEY, HAYNES + EVERTON And to give an idea of numbers … 27 RUINS: SEGENHOE + CLOPHILL, OLD ST. MARY 15 • … 505 minor structures identified (since then …) of which 91% are WALLS 28 PRE-19TH CENTURY Of which 17% are of SQUARED rubble: 29 • UNCOURSED (1%) No major examples other than … • SNECKED (5&) … rear part of Woburn Lower School (16th century, restored c.1830) • BROUGHT TO COURSES (22%) Bridges • REGULARLY COURSED (72%) MEDIEVAL @ SUTTON 16 • 83% RANDOM rubble: 30 18TH CENTURY BRIDGES: GIRTFORD 17 • • UNCOURSED (51%) • LESSER BRIDGES OVER THE FLITT (CHICKSANDS) & SOUTHILL LANDSCAPE • COURSED (29%) • BLUNHAM & TEMPSFORD BRIDGES – THE LODGE QUARRY • POLYGONAL (14%) • ABUTMENTS OF IVEL NAVIGATION BRIDGES – BROOM • DIAGONAL OR HERRINGBONE (6%) Page 2 of 3
30-35 SECONDS PER SLIDE THE GREENSAND COUNTRY: SANDSTONE STRUCTURES Presentation to Diocese of St. Alban: Church Architects + Surveyors Summer Workshop Various types of coping … 31 VULNERABILITY … about 35% walls are retaining CONDITION 37 … most low, many with openings Generally good … and – as buildings - used with other materials Important to understand that walls are not buildings = criteria for assessment DISTRIBUTION 32 … different to looking at walls in buildings Greensand County … CONSERVATION ISSUES • CUTS ACROSS THREE COUNTIES Loss 38 • EMBRACING 55 CIVIL PARISHES • DELIBERATE OR ACCIDENTAL • FALLS WITHIN THE CONTROL OF 6 X LOCAL AUTHORITIES – 81% OF AREA CBC Neglect 39 However, this does not reflect distribution … • FREESTANDING AND RETAINING WALLS MORE EXPOSED • ONLY 34 PARISHES … OF WHICH 18 = 5+ AND ONLY 11 = 10+ • LOSS AND DETERIORATION OF COPINGS LACK OF USE: UNOCCUPIED FARM BUILDINGS 40 Authority split = nearly 35% in Buckinghamshire • • UNMANAGED VEGETATION 41 GREENSAND COUNTRY IS NOT JUST ABOUT BEDFORDSHIRE ! • DISTRIBUTION BY LOCATION 33 Salts 42 … 3 x major concentrations … not generally a problem in an unpolluted mainly rural environment, but: … tends to related to local supply of stone (pit as well as quarries) DE-ICING SALTS (ROADS & PAVEMENTS) 43 • GROUND WATER: RETAINING WALLS + BURIAL GROUNDS (5%; 10-12 YEARS) 44 … nature of stone determines how used: • • DIAGONAL + HERRINGBONE IN POTTON AREA ROAD SALTS & GROUNDWATER 45 • • SQUARED RUBBLE CONCENTRATED IN CENTRAL AREA ( CLOPHILL , SILSOE ) Inappropriate repairs • RANDOM RUBBLE BROUGHT TO THIN COURSES = BUCKINGHAMSHIRE CEMENT POINTING: ADDS TO THE SALTS PROBLEM 46 • DENSE & LOOSE CONCENTRATIONS 34 FAILED CEMENT POINTING 47 • Dense clusters 35 • FAILURE OF LIME MORTARS: LACK OF UNDERSTANDING • HEATH & REACH; GREAT BRICKHILL; LITTLE BRICKHILL; STRETCHED COPINGS 48 • BOW BRICKHILL; SILSOE; CLOPHILL ILL MATCHED REPAIRS 49 • Loose clusters POOR WORKMANSHIP: SMEARING EXAMPLE 50 • • FLITTON; MAULDEN; POTTON BUT IT CAN BE DONE … 51 Also small but significant GROUPINGS … END ON POSITIVE NOTE • OVEREND GREEN; POTSGROVE; STEPPINGLEY Church groupings BACK TO CLAIRE … 52 … RELATIONSHIP BETWEEN CHURCH & WALL IS ALWAYS IMPORTANT LOCAL DISTINCTIVENESS 36 Generally modest in scale and largely self-effacing Location is crucial The way in which stone is used is highly localised Groupings and context are important BELONG IN SOME PLACES BUT NOT OTHERS Page 3 of 3
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