CHAPTER III

REGIONAL GEOLOGY

The area known as the West Riding was an administrativedivision of the ancient county of Yorkshire and includesparts of the modern administrative areas of WestYorkshire, North Yorkshire, Cumbria and Lancashire.Geographically the area extends from the high ground(>600m) of the Pennines in the north and west into thelowland areas marginal to the Vale of York in the east.

These major topographic subdivisions reflect changesin the underlying geological formations (Fig. 6). Thehigh mountainous spine of the Pennine area that crossesthe West Riding from north to south, is underlain byhard, durable rocks ranging from Precambrian toNamurian (Carboniferous) in age. The lower ground tothe south-east is underlain by the thick Coal Measuresuccessions exposed in the deeply incised valleys of theYorkshire Coalfield, extending southwards from Leedsto Sheffield. The whole of the eastern part of the WestRiding is underlain by the softer, commonly reddenedrocks of the Permian and Triassic successions, which arein turn, in large part, masked by a thick sequence ofunconsolidated Quaternary glacial sands, gravels andlacustrine sediments extending into the Vale of York(Aitkenhead et al. 2002).

The area is drained by a series of easterly flowingrivers whose valleys also form the principal routeways,from west to east across the West Riding, before joiningthe Humber estuary.

PRECAMBRIAN SYSTEM

The oldest rocks of the West Riding are Precambrian toCambrian (or Ordovician) metasediments, comprisinga structurally complex succession of slates, coarse gritsand conglomerates. They crop out only in the smallinliers of Ingleton and Horton-in- Ribblesdale. Thesemetamorphosed rocks are in general hard and durable,but their intractable nature has generally precluded theiruse for carved stonework. They have not so far beenidentified in the Anglo-Saxon carved and decorativestones of the survey area.

EARLY PALAEOZOIC(ORDOVICIAN TO DEVONIAN SYSTEMS)

Ordovician rocks outcrop as small inliers east of HowgillFells and more extensively in the extreme northwestaround Sedburgh. Historically they were exploited on alocal basis for building stone, flagstones and roofing slates.The Silurian rocks were exploited for flagstones in theIngleton and Horton-in-Ribblesdale areas and were usedlocally for grave stones, boundary and milestone markers.The best known of these stones were the Horton Flagswhich were quarried around Helwith Bridge (from theseventeenth to nineteenth centuries: Mitchell, W. 1985).The massive sandstones of the Austick Grits were alsoused locally for building. Stones from this succession havenot so far been identified in the Anglo-Saxon carvedand decorative stones of the survey area.

LATE PALAEOZOIC(CARBONIFEROUS TO PERMIAN)

CARBONIFEROUS

The Carboniferous succession of the West Riding canbe divided into the traditional lower and upper divisionstermed the Dinantian and Silesian. These two groups arefurther subdivided into three principal lithostratigraphicsubdivisions — a lower unit dominated by marine,fossiliferous, limestones and mudstones — theCarboniferous Limestone Group (Visean and TournasianSeries); a middle unit dominated by thick, non-marine,fluvial sandstones, with subordinate mudstones — theMillstone Grit Group (Namurian Series); an upper divisionalso of non-marine sandstone, mudstones, but principallycharacterised by the presence of thin but economicallyimportant coal seams — the Pennine Coal Measures Group(Westphalian and Stephanian Series).

23

CHAPTER III24

Dinantian, Carboniferous Limestone Group(Tournasian and Visean)

The limestones that dominate this unit principally cropout in the north west of the area around Craven andAskrigg. Lithologically the limestones of these two areasshow strong contrasts. In the Askrigg area the limestonesare characteristically dominated by thickly bedded, coarsegrained, fossiliferous limestones. These limestones formedas shallow marine reefs and inter-reef shallow seas on ageologically stable structural platform known as theAskrigg Block. In contrast, to the south of this faultbounded block, in the Craven Basin, the area hasundergone considerable subsidence and a thick marinesuccession of deeper water limestones and mudstones,which includes small mud mounds (or reef knolls) isdeveloped.

Stones from this limestone succession have not so farbeen identified in the carved sculptural stones of thesurvey area. They are, however, a common componentof the vernacular building material in the area of theiroutcrop in the southern part of the Yorkshire Dales.

Silesian, Millstone Grit Group (Namurian)

This irregular block and basin topography established inthe Dinantian, initially continued into the succeedingNamurian stage. At first the still rapidly subsiding basinalareas continued to be filled with thick sequences of deep-water mudstones with thin turbiditic sandstoneincursions. Gradually, however, this localised subsidenceslowed and the topography stabilised. In the lateNamurian the now shallow basin area was completelyinfilled with a series of thick, coarse grained, fluvio-deltaicsandstone beds with minor mudstone and siltstoneinterbeds. The sandstones form the prominent, craggyescarpments that typify much of the Millstone Grit Groupsuccession that crops out from north to south along thecentral part of the West Riding, extending from MashamMoor in the north to Howden Moor in the south.

The sandstones can range from fine- to very coarse-grained and are generally well cemented by natural silicacement. They contain variable amounts of feldspar grainsand mica flakes. The importance of the sandstones fromthis group in local culture and the areas economy isdifficult to understate. The siliceous nature of thesandstones lead to their pre-Roman use as quern or grindstones, as for example at Great ‘Whernside’ and frommedieval times until the early twentieth century theyprovided a major sources of millstones which were

distributed throughout Britain and Europe (Morey andDunham 1953; Radley 1963–4). There are few towns,villages or rural settlements in the West Riding fromany period which do not contain building stone quarriedfrom these sandstones (e.g. Blacker 1995; 1996). Manyof these sandstone beds are individually named, but ingeneral when examined in isolation they are extremelydifficult to distinguish in hand specimen one fromanother, because of their similar petrological character.Geologically, each of these sandstone beds form the basalpart of a repetitive series of fluvial cycles which typicallyshow an upward transition from coarse, sometimes pebbly,coarsely cross-bedded, channel sandstone into finergrained, laminated sandstones, siltstones and mudstones.

Stones from the sandstone of this succession form oneof the principal sources for the Anglo-Saxon carved anddecorative stones of the survey area (Fig. 8).

Silesian, Pennine Coal Measure Group(Westphalian and Stephanian)

In the West Riding the Coal Measure successionprincipally outcrops in the area of the Yorkshire Coalfield,which extends from Leeds in the north to Sheffield inthe south, and from Halifax in the west to Castleford inthe east at its widest point. Small, isolated, fault boundedoutcrops of Coal Measures also occur at Ingleton(Ingleton Coalfield) and around Harrogate and Ripon.Like the Millstone Grit sandstones these sandstones havebeen exploited both for cultural and commercial reasonssince prehistoric times, throughout the area of theiroutcrop.

The more general basin-wide subsidence thatcharacterised the later part of the Namurian continuedinto the Westphalian. During the Westphalian, however,the high energy, coarse grained, deltaic sandstones weregradually replaced by sedimentation that characterisesquiet-water, lacustrine and swamp settings in which thelush vegetation that was to eventually form the coal seamsbecame widely established. Cyclic sedimentation is againcharacteristic of the basin fill, with each cycle comprisingalternations of sandstones, mudstone and siltstones andcompleted by a coal seam development.

The working of these sandstones again dates from pre-Roman times, as at Wharncliffe near Sheffield (Wright1988). Many of the sculptural stones examined withinthe survey area over the Coal Measures outcrop are likelyto have a provenance from sandstone in this succession(Fig. 9).

REGIONAL GEOLOGY 25

PERMIAN

Cadeby Formation — formerly the Lower Magnesian Limestone— and Brotherton Formation — formerly the Upper MagnesianLimestone

The Magnesian Limestone (Cadeby Formation) cropsout in a narrow band extending from Ripon in the northto Anston in the south. Towards the end of theCarboniferous, a marked change in climatic conditionsis evident in the succeeding rock successions of both thePermian and Triassic systems. A major period of tectonicplate movements (the Variscan Orogeny) lead to acomplete change in the depositional setting andenvironments across the area. These movements initiateda transition to more arid desert conditions characterisedin the early Permian by the deposition of coarse grained,terrestrial, wadi-fill breccias and yellow sandstones of windblown origin. The latter formed a series of low sanddunes on a then emergent Carboniferous rocky platform.These basal Permian breccias and sandstones are thinand discontinuous across the area. They are generallypoorly cemented and do not provide a viable source ofbuilding or sculptural stones.

In the late Permian the depositional setting againchanged dramatically, with the rock platform graduallysubsiding to be flooded from the east by a highly salinesea. This ‘Zechstein Sea’ which extended eastwards as faras Poland, was bordered along its western shoreline by aseries of carbonate (limestone) shoals and reefs. The reefsare well exposed along the whole of the late Permianoutcrop in the West Riding area and form part of thegeological unit known as the Zechstein Group. Withinthis group are two limestone units, the Cadeby (LowerMagnesian Limestone) and Brotherton formations (UpperMagnesian Limestone), which are of particular significanceas sources of building and sculptural stone in both theWest and East Riding.

Mineralogically the most distinctive aspect of theircomposition is their magnesium carbonate-rich nature.These rocks can therefore be described as dolomiticlimestones, formed by mineralogical changes that haveoccurred since their original deposition as calciumcarbonate limestones. Lithological and petrographicalvar iations within these dolomitic limestones areparticularly important. The process of dolomitization(magnesium enrichment) is thought to have occurredsome considerable time after deposition, and has resultedin a variety of mineralogical and textural (or diagenetic)changes in the limestones. In some areas the original

bioclastic (fossiliferous) or ooidal fabric of the limestonesis intact, but in others significant alteration has occurredto form a finely crystalline dolomite in which much ofthe original bioclastic or oolidal fabric has been replaced.Careful study of samples of the limestones from the areahas enabled these transitions to be mapped out in somedetail, allowing the provenance of worked or decorativestones from the sequence to be better established(Hart 1988).

Stones from these limestone units locally form asignificant proportion of the Anglo-Saxon carved anddecorative stones so far examined in the eastern part ofthe survey area (Fig. 10).

TRIASSIC

Sherwood Sandstone Group — formerly Keuper Sandstone— and Mercia Mudstone Group — formerly Keuper Mudstone

Arid conditions continued into the succeeding Triassic.The ‘Zechstein Sea’ gradually contracted to be replacedby a depositional basin criss-crossed by heavily sand-laden,fluvial channels. A thick sequence of these fluvialsandstone cycles developed as the basin gradually subsided(Sherwood Sandstone Group). In the latter part of theTriassic this sandstone deposition was replaced by anextensive area of saline playa lakes in which red mudstoneswere deposited, sometimes with thin evaporitic beds ofhalite and/or gypsum commonly developed.

Triassic sandstones from the Sherwood SandstoneGroup, though generally less durable than those fromthe Carboniferous sandstones, have been exploited overtheir outcrop in parts of the Pennine area for buildingstone but do not occur in the decorative stones examinedduring this study.

JURASSIC, MIDDLE

Ravenscar Group — Saltwick Formation

One stone sculpture examined was carved from sandstonefrom outside the West Riding area. This sandstone wasprobably sourced from the Middle Jurassic RavenscarGroup strata of the North Riding which principally cropout in the North York Moors and Howardian Hills(Hemingway and Knox 1973). These sandstonesaccumulated in a fluvio-deltaic environment as channeldeposits which, locally, have been extensively exploitedsince the Iron Age for quernstones, building and artefactstone (Briggs 1988; Senior 2001).

CHAPTER III26

Geological Period

Triassic

Permian (Zechstein Group)

Carboniferous

TABLE 2Stratigraphical divisions in western Yorkshire

REGIONAL GEOLOGY 27

FIGURE 7The distr ibution and geology of all sculptural fragments examined in western Yorkshire

CHAPTER III28

STONE TYPES USED FOR THE SCULPTURES(Fig. 7)

The various stone types used for the sculptures aredescribed below in stratigraphical order. Three stonevarieties form the principal lithologies used in the Angliansculptural stones of the West Riding — coarse grainedCarboniferous Millstone Grit sandstones, finer grainedCoal Measures sandstones and Permian dolomiticlimestones. A single sandstone example sourced from theMiddle Jurassic succession in the North Riding outsidethe area is also present.

GRAIN-SIZE

All of the stone samples described were examined byhand lens in situ and in hand specimen only. No thinsections were available to carry out a full petrographicanalysis. The grain-size descriptions of both thesandstones are based on the standard Wentworth (1922)classification scheme. Sandstones are siliciclastic rockswhose grain-sizes must lie between 0.032 and 2 mm.The scheme distinguishes five sandstone categories —very fine sand < 0.125 mm, fine sand < 0.25 mm,medium sand < 0.5 mm, coarse sand < 1 mm and verycoarse sand < 2 mm. Grains from 2–4 mm in size aregranules, and grains > 4 mm are pebbles. This grain-sizescheme is also applicable to limestone lithologies, e.g. ina coarse grained limestone the carbonate grains or crystalsmust predominantly lie between 0.5 and 1 mm in size.In general variations in grain-size are rarely sufficient toidentify the source of a sandstone or limestone; however,on occasion the presence of quartz pebbles of a certaintype can narrow down the search, e.g. some Leeds crossfragments and the East Riddlesden Hall cross-shaft(p. 148) occur near to pebbly sandstone sources in theBramley Fall area, Rough Rock Formation (MillstoneGrit Group), the source of sandstone for medievalKirkstall Abbey.

SANDSTONE MINERALOGY

The sandstones described in the sculptures are all detritalsiliciclastic rocks of Carboniferous age. Mineralogically,siliciclastic rocks are defined as those in which clasticfragments or grains derived from the weathering andbreakdown of pre-existing siliceous rocks make up morethan 50% of the rock. In the sculptural sandstones silicategrains make up more than 95% of the framework grains:these are dominated by quartz (translucent or white withsub-conchoidal fracture surfaces) with variable amountsof feldspar grains (opaque and variegated with distinctplanar cleavage planes). Other grains commonly present

include platy micas (muscovite), organic fragments andpervasive small, white patches of the clay mineral kaolinite.These framework grains are bound together by naturalcements that in these sandstones are almost exclusivelycomposed of silica (quartz). The presence of such silicacements is evident in some specimens from the sparklingcrystal faces exposed at fractured surfaces in the sandstone.Note that identification and estimations of theproportions of these different mineral components, usinga hand lens, is generally only feasible in the coarser grain-sizes.

LIMESTONE MINERALOGY

Limestones are defined as those rocks where calcium ormagnesium carbonate minerals form more than 50% ofthe rock. In the sculptural stones the limestones foundare all of Permian age and are composed principally ofmagnesium carbonate and can therefore described asdolomitic limestones. Formed as reefal limestoneaccumulations, which are thought originally to have beenof calcium carbonate, over geological time they haveundergone substantial changes to their mineralogicalcomposition and textures by a process known asdiagenesis. The limestones now commonly show onlyremnants of their original bioclastic or ooidal componentsor may be completely recrystallized, removing any traceof their original depositional components. Such texturalvariations can occasionally be used to determine theprovenance of a limestone.

SEDIMENTARY STRUCTURES

In many of the sandstone sculptural fragments examined,traces of an original sedimentary fabric are evident: mostcommonly this fabric takes the form of marked layeringor lamination in the sandstone. In general suchsedimentary features would be avoided and more massivesandstones preferred, as they could form lines of weaknessalong which failure could occur during dressing andcarving of the stone. Where such laminae show a low-angled relationship to the stone surface it is described ascross-bedding, which is characteristic of originaldeposition of the sand in a high energy, confined, channel.Pronounced cross-bedding is a noticeable feature in someof the sculptural fragments but does not generally appearto produce a weak stone. However, as cross-bedding isubiquitous in both the sandstones of the Millstone GritGroup and in some coarser Pennine Coal Measuressandstones, which were all deposited in similar fluvialchannels, as part of the major Carboniferous river system,it cannot generally be used as a provenance indicator forthe quarry source.

REGIONAL GEOLOGY 29

FIGURE 8The distr ibution of sculptural fragments of sandstone from the Millstone Grit Group

(Upper Carboniferous) succession

CHAPTER III30

In contrast, where lamination occur parallel to thesculpture surface, as in pieces at Ilkley and Harewood,lines of weakness have clearly developed along the laminae(Ills. 329, 363). Parallel lamination of this type, which isalso commonly associated with finer grain-sizes andmicaceous or carbonaceous concentrations, would suggestquite strongly that a source in the Pennine Coal MeasuresGroup is more likely. In more recent times parallellaminated sandstones from the Pennine Lower CoalMeasures (Elland Flags) have been the principal sourcesof fissile sandstones for roofing or paving purposesthroughout the West Riding area.

COLOUR

When freshly quarried, Carboniferous sandstones in theWest Riding show a wide range of colours from grey-greens, pale yellows to variegated browns and reds. Thecolour variations are principally due to changes in thecomposition and weathering state of the iron mineralsdispersed in very small proportions throughout the rock.In stone provenancing these colours could be effectivelyused to narrow down stone sources. The most immediateproblem, however, when examining and describing thesculptural stones is the frequent discoloration of the stonesurface by air-borne pollutants. Many of the fragmentseither still stand or clearly stood outdoors in the pastand have been subsequently re-sited indoors.Consequently, it is rarely possible to determine the truecolour of many of the stone surfaces examined, unlessdamage has occurred exposing a clean fractured surface.Only on rare occasions do the sculptural stones show acolour distinctive enough to be helpful in provenancingthe quarry source. Locally, in parts of the West Riding,for example, some Carboniferous sandstones show adistinct natural reddened coloration. Examples of suchreddened sandstones in sculptural pieces occur at anumber of locations, e.g. Follifoot and Ripon, whichmay be attributable to local sources. However, some careneeds to exercised when provenancing all reddenedsculptural pieces as it is also clear that a numbershow some signs of burning which also can producesignificant surface reddening in both sandstones andlimestones, e.g. Barwick in Elmet (p. 93, limestone),Burnsall (p. 107, sandstone).

UPPER CARBONIFEROUS SOURCES (Figs. 8 and 9)

The stones most widely used in the sculptures of theWest Riding are sandstones from the Millstone Grit(Namurian) and Pennine Coal Measures groups(Westphalian). Though broadly similar in character,sandstones from these two groups can only bedistinguished petrographically by changes in grain-size,mineralogy, cementation and colour. Over much of theWest Riding area the sandstones of the Millstone GritGroup (MGG) generally show coarse, often pebbly grain-size, quartzose compositions and hard siliceous cements.In contrast those from the Pennine Coal Measures Group(PCMB) have generally proved to be finer in grain-size,more feldspathic in composition and less well cemented.However, this is not invariably the case and each sculpturalpiece must be compared directly with local sandstonevarieties before reaching a firm conclusion as to theirprovenance. More precise provenancing of thesesandstones has been achieved in recent years by the useof heavy mineral analysis but requires access to largesamples for destructive preparation, clearly a step too farin this project (Hallsworth and Chisholm 2000).

While a broad subdivision of the Carboniferoussandstone sculptural pieces is usually possible into eitherMillstone Grit or Pennine Coal Measures varieties, it ismore difficult to relate the stones to specific local quarriesor sandstone beds. Despite the proliferation of goodquality sandstone for building and decorative stoneworkin the West Riding and their widespread use frommedieval times onwards, there are few studies on earlyquarrying activity in the Carboniferous sandstonesuccession of the West Riding area (Moorhouse 1990).The principal published and unpublished studies relateto provenancing the sandstones used in Roman Yorkwhich have generally been ascribed to the closestaccessible outcrops in the area at Thorner (RomanPompocali) where evidence of early quarrying activityhas been documented.

One other feature of possible interest in provenancingthe sandstones is the occurrence in some of the easternoutcrops of reddened varieties. The natural reddening issometimes clearly associated either with their occurrencebeneath reddened Permo-Triassic beds, from which thecolour is subsequently derived by staining frompercolating groundwaters, by contemporaneousdeposition in arid, desert-like environments, or may be aconsequence of iron pan concentrations within channelsandstone bodies. Alternatively it is also clear that thereis evidence that some reddened sandstones may be theresult of fire damage, e.g. Otley (p. 215).

REGIONAL GEOLOGY 31

FIGURE 9The distribution of sculptural fragments of sandstone from the Pennine Coal Measures Group

(Upper Carboniferous) succession

CHAPTER III32

PERMIAN DOLOMITIC LIMESTONE SOURCES (Fig. 10)

Those sculptural stones found at sites close to the outcropof the Permian Cadeby Formation (Lower MagnesianLimestone) along the eastern margin of the West Ridingarea are most commonly carved from the local limestone.These dolomitic limestones were quarried extensivelyalong the whole length of the outcrop but wereparticularly important, from Roman times, in the vicinityof Knaresborough–Tadcaster (Roman Calcaria) and inthe Conisbrough–Doncaster areas. The Permiandolomitic limestones can show considerable texturalvariations along the outcrop. The stones from both theTadcaster and Conisbrough areas show a range ofdistinctive lithologies including bioclastic, ooidal, finelycrystalline and porous finely cellular textures, the latterformed by the dissolution and recrystallization of originalooidal framework.

Limestones from the Cadeby Formation were favouredby the Romans when building some of the military andcivilian structures in York (Eboracum), Aldborough(Isurium — Staveley Quarry) and elsewhere. The CadebyFormation has provided, and still provides, the mainbuilding stone for the great cathedrals of York (JackdawCrag Quarry, Tadcaster), Beverley (Smawse Quarry,Bramham Moor) and Southwell (Mansfield WoodhouseQuarry, Mansfield). The abbeys at Selby (Park NookQuarry), Roche (Roche Abbey Quarry) and Welbeck,and the great Norman castle of Conisbrough, are alsoconstructed of locally quarried Magnesian Limestonefrom the formation.

A second limestone formation recognised in thePermian succession is the overlying BrothertonFormation (formerly the Upper Magnesian Limestone).In general this formation is more thinly bedded in naturethan the Cadeby limestones, however, there is a possibilitythat in some areas the beds have thickened sufficientlyto provide a second source of sculptural stone. In general,however, the two limestones may be hard to differentiatein sculptural fragments.

MIDDLE JURASSIC SANDSTONE SOURCES

One sculptural stone found at Ripon (no. 1, nowin the Yorkshire Museum), is the only piece that hasbeen transported into the area from further afield.Lithologically this sandstone is consistent with a sourcein the Saltwick Formation of the North Riding area;however, this formation was quarried widely across itsoutcrop in the North York Moors, and at this stage itwould be imprudent on present geologicalknowledge to identify a specific quarrying area as thesource (Senior 2001).

SOURCING AND TRANSPORTING THESTONES

CARBONIFEROUS SOURCES

The geological succession and topography of much ofthe West Riding area is dominated by its numerousCarboniferous sandstone outcrops. Sources of durablesandstones for use in building, as tools or for sculpturalstonework are locally plentiful in both the Millstone Gritand Coal Measures groups. In general, therefore, thepresent survey suggests that there is little support forsourcing the stones from a restricted number of sources,but rather that suitable stone could be widely procuredfrom local sources. It seems more likely that the moreskilful stone carvers were itinerant workers who pliedtheir trade wherever needed without having to be overlyconcerned with transporting stones over long distancesfrom specific quarrying areas.

MILLSTONE GRIT GROUP SANDSTONES (Fig. 8)

The sandstones of the Millstone Grit Group form themost durable of the stones available for sculptural workin the West Riding. Their use in many of the sculpturalpieces examined shows a wide distribution across theWest Riding but is particularly prominent in the area tothe north of Wakefield. This is not, however, particularlyenlightening as this area is also effectively the principallocation of the Millstone Grit Group outcrop.

As might also be expected, there are present dayconcentrations of sculptural pieces along the mainsettlement and communications arteries, the Wharfevalley, from Ilkley and Otley to Bardsey and KirkbyWharfe and, to the south, along the Aire valley fromKildwick in Craven to Leeds, Rothwell and Wakefield.In the areas further to the north there are a smallernumber of scattered pieces at Middlesmoor, SouthStainley and Ripon, and to the south at Bolsterstoneand Sheffield. As yet, however, it is unclear how many ofthese pieces are in situ or could have been redistributedat some earlier period.

The Millstone Grit sandstones of the West Ridingoccur prominently in the Roman buildings of York, andtheir possible quarry sources and supply routes have beendescribed in some detail by Buckland (1988) and Gauntand Buckland (2002). Sources along the eastern marginof the Millstone Grit outcrop have been suggested aroundThorner, where the Wharfe eventually emerges ontothe Vale of York. It is generally thought that themovement of these sandstones downstream by rivercarriage is the most likely method of transportation.Conversely it is also likely that transportation upstream

REGIONAL GEOLOGY 33

FIGURE 10The distr ibution of sculptural fragments of limestone from the Cadeby and Brotherton formations

(Upper Permian Zechstein Group) succession

CHAPTER III34

would be logistically more difficult, and other quarrysources higher up the Wharfe and Aire valleyswatercourses would probably have been used to supplystone for the Roman sites at Ilkley (Olicana) and Elslack(Olenacum). By the ninth century therefore it is likelythat many of the best sandstone sources in the WestRiding would have been exploited and be relatively wellknown to the local Anglo-Saxon population.

REUSE OF ROMAN STONE IN ANGLIAN SCULPTUREIN THE WEST RIDING

The network of Roman buildings known in the WestRiding, many of which contained stone structures,provide evidence not only that good building stone wasreadily available, but also that a significant stone workingindustry must have existed in each local area. However,in the East Riding the situation was considerably differentas no useful building materials crop out. Consequently,the principal centre of Roman ‘occupation’ at York(Roman Eboracum) had to import all its building materialsfrom surrounding areas. The principal sources of buildingstone were quarries in the Millstone Grit sandstones andCadeby Formation limestones of the West Riding (Gauntand Buckland 2002). Whilst there is a wealth of evidenceof the reuse of such Roman stone sources in laterbuildings in the East Riding (Morris 1988), there is littleor no evidence that these stones were returned to theWest Riding for subsequent use as building stone, or forrecutting for use in its Anglian sculptures.

In the north Lincolnshire–Humberside areas a numberof sites have been described where Roman stones havebeen reused both in buildings and in pre-Conquest crosses(Stocker with Everson 1990; Everson and Stocker 1999).In the best documented instances the reused (andtherefore possibly re-cut) stones identified areCarboniferous Millstone Grit sandstones, believed to havebeen transported from York (Eboracum) (Gaunt andBuckland 2002; Senior 2001). In the West Riding nospecific examples of reused Roman stones in Anglo-Saxon sculptures have so far been confirmed. This maybe because many of the West Riding sculptural piecesare of a fragmentary nature and difficult to re-assemblewith confidence. However, it is also perhaps becauseoverland transportation of large stones westwards from

York would have been a major logistical problem, whereasthe river transportation from York gave easier access viathe Ouse to the Humber–Trent navigations and theirsouthern hinterlands.

PENNINE COAL MEASURE GROUP SANDSTONES(Fig. 9)

The finer grained sandstones of this group arerecognisable in many of the Anglian sculptural stonefragments of the West Riding. Though generally lessdurable in character than the Millstone Grit sandstonesthey were commonly selected and used for the sculpturalpieces found in locations throughout their outcrop area(Cawthorne, Dewsbury, Penistone etc.). Unlike theMillstone Grit sandstones, however, they rarely appearto have been transported far beyond their immediateoutcrop. Where river access and a major ‘market’, i.e.Roman York, was available, the nature of the stones madethem more sought after as flagstones rather than fordecorative carved work in earlier times (Buckland 1988).

PERMIAN — CADEBY AND BROTHERTONFORMATIONS (MAGNESIAN LIMESTONES) (Fig. 10)

Unlike the Millstone Grit sandstones the sculpturallimestones pieces of the Permian show a much morerestricted distribution in the West Riding. There areeffectively two principal concentrations, the first alongthe Wharfe around Collingham and Tadcaster, the secondaround Mexborough and Conisbrough in the south ofthe area. The limestones of these two principal areas showsome contrasting petrographic features which suggest thatin each area local quarries were used to provide the stonefor sculptural work.

In the Collingham and Tadcaster sculptural limestonefragments, the limestone shows the typical finelycrystalline and cellular (finely ooidal or peloidal) structurecommon to all the Cadeby limestones of this area. Thelimestone sculptural pieces of the Mexborough andConisbrough area, which show similar cellular textures,show very few petrographic differences. Consequently,it appears that there would be little need to transport thestones far from their original quarry sources. Both areascontain suitable stones and have remained importantlimestone sources to the present day.