THE GREENSAND COUNTRY: SANDSTONE STRUCTURES 30-35 SECONDS PER SLIDE Presentation to Diocese of St. Alban: Church Architects + Surveyors Summer Workshop COMPOSITION 06 INTRODUCTION (TITLE PAGE) 01 Quartz (silica) particles = 0.07-2.0mm TALK Most particles unconsolidated or weakly bound About how sandstone plays a part in the character of the Greensand Country 02 … much of rock is sand = useful only as an aggregated Going to deal with: Some horizons towards upper levels • PROPERTIES OF THE STONE …. tightly bound with more quartz and iron oxides = can yield a reasonable building • SOURCES stone • HISTORIC USAGE GENERALLY …. Albeit discontinuous and irregular • 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 Based on AUDIT of minor sandstone structures + their context carried out in 2015 • HIGH IRON OXIDE = FRIABLE & PRONE TO EROSION … one of a number of studies that fed into Landscape Conservation Action Plan Harder stones for building; more friable for boundary walls, etc. … its aim being to: Bedding … general comment • INCREASE UNDERSTANDING OF THE ROLE PLAYED BY MINOR SANDSTONE • DETERMINES MAXIMUM SIZE OF STONE & WAY IT IS USED STRUCTURES & THEIR CONTEXT IN THE DISTINCTIVE CHARACTER OF THE GREENSAND LANDSCAPE. COLOUR 08 • IDENTIFY HOW SURVIVAL IS THREATENED Regardless of how the rock is cemented …. iron rich compound • 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 METHODOLOGY Other minerals • GLAUCONITE = IRON-POTASSIUM SILICATE Literature review 03 • HUSBORNE CRAWLEY CHURCH Field survey 04 • UPPER AND LOWER GREENSAND CONFUSION Analysis WORKABILITY 09 PROPERTIES … WHAT ARE WE TALKING ABOUT? Usable stone is not a freestone despite small particle size • DIFFICULT TO CARVE GEOLOGY 05 • RARELY USED FOR MOULDINGS OR COMPLEX DETAILS Underlying 120 metre thick layer of sedimentary rock • CANNOT BE WORKED AS ASHLAR • DISTINCTION BETWEEN ROCK AND STONE Always used as Rubble Laid down 110 to 125 million years ago • RANDOM & SQUARED; SOMETIMES COURSED Generally hidden by layers of clay and other soils Often combined with other materials 10 Historically known as the Lower Greensand … • TOTTERNHOE STONE; PEBBLES, RIVER COBBLES (IVEL), ETC. … though more correctly the WOBURN SANDS FORMATION Page 1 of 3 THE GREENSAND COUNTRY: SANDSTONE STRUCTURES 30-35 SECONDS PER SLIDE Presentation to Diocese of St. Alban: Church Architects + Surveyors Summer Workshop SOURCES … WHERE DID IT COME FROM? OTHERWISE … IN TERMS OF OCCUPIED BUILDINGS 18 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 CURRENT SUPPLIES Other buildings All mainly aggregate, often on massive scale • SUTTON PARK HOUSE (1858) NOW JOHN O’GAUNT GOLF CLUB 19 • 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 USAGE … HISTORY This is compared to 43 churches that are in whole or in part sandstone … 22 … including further afield there are 71 sandstone churches + chapels CHURCHES 14 Churches aside, the contribution of sandstone to the character and identity of the Many of medieval foundation … Greensand Country = clusters of MINOR STRUCTURES, primarily walls. 23 … but little medieval stone, at least externally. MINOR SANDSTONE STRUCTURES 19th (some 20th) century … … restoration TYPOLOGY • MILLBROOK (1857-8); LITTLE BRICKHILL (1864-5); HUSBORNE CRAWLEY (1911) Walls but also: … rebuilding • UNOCCUPIED FARM BUILDINGS 24 • STEPPINGLEY (1858-60); MAULDEN (1858-9) • BRIDGES 25 Externally, some survival • MISCELLANEOUS 26 • 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 No major examples other than … • UNCOURSED (1%) • 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 THE GREENSAND COUNTRY: SANDSTONE STRUCTURES 30-35 SECONDS PER SLIDE 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 • EMBRACING 55 CIVIL PARISHES 38 • FALLS WITHIN THE CONTROL OF 6 X LOCAL AUTHORITIES – 81% OF AREA CBC • DELIBERATE OR ACCIDENTAL However, this does not reflect distribution … Neglect 39 • ONLY 34 PARISHES • FREESTANDING AND RETAINING WALLS MORE EXPOSED … OF WHICH 18 = 5+ AND ONLY 11 = 10+ • LOSS AND DETERIORATION OF COPINGS Authority split = nearly 35% in Buckinghamshire • LACK OF USE: UNOCCUPIED FARM BUILDINGS 40 • GREENSAND COUNTRY IS NOT JUST ABOUT BEDFORDSHIRE! • UNMANAGED VEGETATION 41 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 … nature of stone determines how used: • GROUND WATER: RETAINING WALLS + BURIAL GROUNDS (5%; 10-12 YEARS) 44 • 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 Also small but significant GROUPINGS BUT IT CAN BE DONE … 51 • OVEREND GREEN; POTSGROVE; STEPPINGLEY … END ON POSITIVE NOTE 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 .