EXPANSION E ANTONINTH N O S1 16 E WALL.

X.

E NATURTH PURPOSD E EXPANSIONSAN ETH F E O E TH N O .

BY K. A. STEER, M.A., PH.D., F.S.A., F.S.A.Scoi.

INTRODUCTORY. A minor, but intriguing, problem concerning the Antonine Wall is presented by the occurrence, in the central sector, of a number of platforms projecting fro soute mth hRampart.e sidth thesf f eo o x e Si platforms1 r o , "expansions" as they are commonly termed, are either visible today or on hardln mattea ca record e t yi b chanc f d o r an , e that they fall into pairs— two being located in the Tentfield Plantation to the E. of Rough Castle fortbetweeo tw , n Rough Castl Bonnysidd e an weste th n -o e o Housetw d ,an slopn er f Croeo y Hill.2 Detail individuae th f o s l expansion givee sar n ni an Appendix (p. 169), and here it is sufficient to drawattention to the following general points: 1. At the present time the five surviving examples are all more or less semi-circular on plan, and it has sometimes been taken for granted that this was their original shape. Two of them measure 50 ft. from Rampare th t a . tW fac, whilo 30-4y t S. b e e . o . efroE t th 0 ft . mN other three are somewhat smaller, measuring about 35 ft. from E. to W. by some 20 ft. from N. to S. The sixth expansion on the other hand, Tentfield West, whose outline is no longer visible, is described as being square by both Gordon and Roy, and according to Roy's drawing measured abou. alonft 8 g1 t each side. 2. Trenche t througexpansiono scu tw f e o h th d Cron so en ye Hilth t a l 19te th h century showed that they were buil turff to , likRampare eth t itself werd an , e addeRampare th o dt t soma t e time afte construcs it r - tion, though probabl t lon thef y no lais o g me dafterwa directlOn . y on the living rock, whereas the other rested on a rough base composed of large boulders. 3. The analogy which has sometimes been suggested between the expansions and the turrets on Hadrian's Wall is inapt, since the 1 Cf. Macdonald Romane ,Th Wall ,n i editiod 2n n (1934) 350-8. ,Antoninepp e Th ; Wall Report (1899), pp. 144—9. The abbreviations RWS and A.WR are used hereinafter to refer to these sources. r convenienceFo 2 expansione th , questiosn i referree nar throughouo dt t this pape Tentfields ra East West,d an Bonnyside East West,d an and Croy Hill EastWest.d an 1 1 . VOLXC . 162 PROCEEDING E SOCIETYTH F O S , 1956-57.

expansion t spaceno t e regulaa dar s r intervals o d thern an 1s i e reaso supposo nt e that ther eves echairwa a thef no m extending from end to end of the Wall. Only two other possible examples were noted compilere th y Antoninee b th f so Wall Report,thesef o d , an one , near Dullatur railway station,2 proved on excavation to be a natural mound,3 while the second, 160 yds. E. of Bonnyside House,4 is so intangibl t surprisinno e s thai t i tg tha s sponsorit t s concludey b d honestly admitting "i scarcels i t y thought tha regardee tb thin sca d as one of the expansions." cuttinge 4Th . s made throug Croe hth y Hill expansions she ligho dn n o t their purpose, which remained unexplained. Since four of the six known expansions are situated in Stirlingshire, the Royal Commissio e Ancienth n Historicad no an t l Monument f Scotlano s d decided to undertake the complete excavation of one of them in 1957, as a contribution towards the forthcoming Inventory of that county. By a fortunate coincidence lair M ,n Maclvo Anciene th f o r t Monuments Inspec- torate was simultaneously making plans for the re-examination of the fort of Rough Castle which, together with an adjacent stretch of the Antonine Wall s recentlha , y been placed unde e guardianshith r pe Ministr oth f f yo Works, and a joint excavation was therefore arranged. The Commissioners indebtee ar Ministre th o d t supplyinr yfo g labou equipmentd an r alsd oan , Scottise th o t h Field Schoo Archaeologf o l providinr yfo g fund maintaio t s n four student helpers who divided their time between the two enterprises.

THE EXCAVATION. e expansioTh n selecte r excavatiofo d s Bonnysidewa n East, whics i h situated f Rougaboue poino yds 0 th . f 50 W tho . yds 0 . Castl6 W . d ean wher e tracth e k from Woodside Cottage join e publith s ce th road. s A 5 contoured plan shows (fig. 1) its present shape is far from being a true semi- circle, and its overall measurements are about 40 ft. from E. to W. at the Rampart face, by about 18 ft. from N. to S. Unlike Bonnyside West it has no flat top, the profile exhibiting a fairly uniform slope, 3 ft. in vertical height, from the base of the expansion on the S. to the junction with the Rampart. The Rampart itself is well preserved where it is buttressed by expansione th t diminishei t bu , heighn si eithen o t r side. Immediatelo yt the E. it has, in fact, been completely eroded away by flooding, while to the W., and just inside the left-hand margin of fig. 1, a former excavation has left a pronounced scar on the crest. 1 Measured alon Kamparte gth Tentflele th , yds0 d 65 . paiaparte ar rBonnyside th , e ydspai0 35 r. apart, and the Croy Hill pair less than 150 yds. apart. 2 AWR, p. 147. 3 RWS, p. 351, n. 1. 4 AWR, p. 107. 6 O.S. 6-iuch map, Stirlingshire Nxxx NW.; Nat. Grid ref. NS/838798. Cf. RWS, PI. LIX, 1. EXPANSIONS ON THE ANTONINE WALL. 163

firse th t n instanceI seriea , parallef so l trenchet frocu m. s S Nswa o t . through the expansion, at intervals of 3 ft., as far as the inner kerb of the Rampart. These trenches enable examino t s du e structureth crossn ei - EXPANSION, BONNYSIDE EAST

•SCALE Iff

Fig. 1. same th section et a tim d determino et an , shapes e it whed intere an ;n th - vening balks were removed a complete east-west section of the expansion was reveale neas da possibls ra poine th junctio f o o tet n e wit facth e hf th e o Rampart (fig , C-D)3 . . Finally cuttina , mads gwa e throug Rampare hth t itself, in line with the centre of the expansion, in order to produce a trans- verse section through both works (fig. 3, A—B). At the conclusion of the 164 PROCEEDING E SOCIETYTH F O S , 1956-57.

excavation the excavated soil was replaced and the expansion restored to formes it r condition. At this point the stone foundation of the Rampart proved to be 14 ft. 9 ins. in width, and the Rampart itself survived to a height of 4 ft. As is usual in the Bonnyside sector, the individual layers of turf were easily distinguishabl e sectioth n ei n (fig , A-B)3 . e blacth , k lines formee th y b d decayed vegetation standin t sharplgou y fro e interveninmth g bandf o s grey or ochre sandy earth, and traces of twenty closely-spaced laminations could be counted. The only unexpected feature was the presence, immedi- ately underneat humuse hth thia f no , cappin boulderf go smald san l stones of the kind that occur locally in the subsoil. At first sight it •was tempting o suppost e tha t herd -we remainha eeth a rampart-walk f o s t carefubu , l trowelling showed that the majority of the small stones were angular frag- ments whose upper surfaces showed none of the signs of wear consistent with a trodden walk. It must therefore be concluded that these stones were formerly scattered throughout the vanished upper portion of the Rampart havd an e settle theio dt r present positio e turfworth s s beena ha kn pro- gressively eroded away. A similar scatter of boulders, small stones and pockets of gravel was discernible in the surviving turfwork on either side of sectione th . excavatioe Th n showed tha presene th t t appearanc expansioe th f eo s ni misleading, and that it was originally square on plan at ground level, measuring 17 ft. along each side (fig. 2). The edges rested on a cobbled foundation whic s neatlwa h y kerbed with boulder e threth en o sope n sides, but the centre was laid directly on the subsoil. On the north side several cobbles overlappe e soutdth he Rampart kerth f bo , demonstrating unequivocally that the Rampart foundation had been constructed first and the expansion base added shortly afterwards. A similar chronological relationship also existed between the expansion and a Roman quarry-pit found underneath it (fig. 2), since the quarry-pit had been filled with turf expansioe byth n builder beed ha n t soo s i dugsa beford s na sily an , tean had .had time to accumulate in the bottom.1 On the other hand the turf superstructure botf so expansioe hth Rampare th d evidentld nan ha t y been laid in a single operation, for not only was there no clear-cut division between them, but several laminations continued without visible interruption from one structure to the other as shown in fig. 3, A-B. It follows therefore tha thin ti Ramparse sectoth d Militare an rth ty basyWa e were constructed simultaneously; the foundation of the expansion was added almost at once; and finally the turf superstructures of both the expansion and the Rampart were erected on the prepared foundations. Such a sequence is indeed a 1 Although they have previously escaped notice, a number of similar quarry-pits from which gravel was obtained for surfacing the Military Way can still be seen immediately behind the Rampart between Bonnyside EastBonnysided an West.f the o portio A e m on appear course f e no th Th f eo fign . si 1 . Militar hereabouty yWa s presumably coincides wit modere hth n road. EXPANSION E ANTONINTH N O S E WALL. 165

ANTONINE

EXPANSION o, 166 PROCEEDING E SOCIETYTH F O S , 1956-57. logical one, granted tha expansione th t s wer integran ea originale parth f o t l design of the Wall, but has now for the first time been demonstrated by excavation.1 In marked contrast to the Rampart, however, the expansion was not of uniform construction throughout: only the outer skin on the exposed sides was carefully buil goof o t d quality turfthicknesa o t , abouf so core ft.3 t th ,e being compose inferiof do r turves laimora dn i e haphazard fashio witd nan h a greater admixture of earth. Although a careful search was made for post-holes, none were found either in the body of the expansion or in the subsoil beneath or around it. It must be concluded therefore that the expansion was not the base for a substantial timber structure, such as a watch-tower or signal-post of the kind found on the Gask ridge near Perth, but that it was essentially a simple platform of sods with a square base, a height sufficient to justify the stone foundation, and the sloping sides which would be necessary to give it stability. No reliable information about the precise angle of the sides was obtainable at Bonnyside East, for althoug wese hnorth-wese th tth standin sids t a e. wa heigha ft t3 o g t f o t corner, the profile showed clear evidence of distortion due to shrinkage and compressio howevee ° turf slopth t A 70 unreasonabl f .f no n o eo s i r r efo turfwork, especially when underpinned wit e e bacth hth f kf o stonei d an , Rampar expansioe . th inclineft s f o 0 angl n wa t1 p a t nt to 6f a d ea 0 o e °,2th above ground level estimatee th , d heighRampart,e th f o t 3 will have taken the form of an oblong area measuring 19 ft. in length from N. to S. by 10 ft. in width (fig. 4).

E PURPOS EXPANSIONSE TH TH F EO . consequencn I excavatioe th f eo Bonnysidef no East e concepo th tw f o t or more types or sizes of expansion * is no longer admissible. Bonnyside Westd Tentfieldan East e similaar superfician i r l appearanc Bonnysideo et East, althougd an h bot e Crohth y Hill expansion somewhae sar t larget a r the present time, the stone foundation of Croy Hill East was only 1 ft. longer (18 ft.) from N. to S. than at Bonnyside East.5 And the ground plan of Bonnyside East is to all intents and piirposes identical with Roy's plan of Tentfield West, the dimensions corresponding to within 1 ft. This uniformity of design implies that the expansions served a common purpose, an t dremaini consideo st r what this purpos havn eca e been. Althouge hth structur t proclaie itselno d di ffunctions m it significana , t furnisheclus ewa d 1 As already stated (supra, p. 161) the Croy Hill expansions were both built independently of the Eampart t thibu ,s fact doe t necessarilsno y denote anything more tha latitudee nth allowe differeno dt t working parties. 2 At Cray Hill Bast the back of the Rampart had a slope of 62J° (AWR, p. 79). The front was no doubt steeper. * RWS, p. 88. 4 RWS, p. 353. stonewore widte th Th 5f ho t Croyka Hill t bee no East ns establishedha t surfacbu , e appearances bot ht Croya her d ean Hill West consistene ar t with square foundations. Proc. Soc. Ant. Scot.} [VOL. XC .

EXPANSION

FALLE.U TUIFWOR.K.' BUR.UT MATIWAL ANTONINE ALL

BUR.WT MATLR-IAL

FAUIW TUR.FWOE-K.

EXPANSION

3 Z / 0 ZO F C.LT

Fig. 3.

. KSTEERA . . [To face p. 106. EXPANSIONS ON THE ANTONINE WALL. 167

t Bonnysidea discovere Eastth y b considerablf yo e quantitie burnf so t wood burnd an t turfwork roun burne basee dth Th t. deposits, interspersed with unburnt material, were particularly prominent amongst the fallen turfwork thacom d angle ha tth res o e t en i t betwee wese nth expansioe t sidth f eo n e Rampartth d an , whil a esimila r deposit, containing fragmento tw f o s

A-

K-A-S'

Pig. 4.

Roman coarse vessels—a yellowish buff mortarium and a black fumed cooking-pot (fig. 5), both heavily burnt—was found lying against the north kerb of the Rampart. The implications of these discoveries are twofold. In the first place, the burnt deposits are clearly the result of successive con- expansione flagrationth f o secondlyd p An to .n presencso e ,th potsherdf eo s implies that troops wer t mereleno y patrollin Rampare gth t thia t s point t werbu e actually statione spoe th t n frodo m tim timeo et . Ther thun eca s be no doubt that Macdonald was right when he suggested that the expansions 168 PROCEEDINGS OF THE SOCIETY, 1956-57.

were neither ramps for staircases, watch-towers, nor artillery platforms, but stance r beacons.e othefo s th n r O hand1 , consideration f spacinso d gan siting mak t impossibli e o believet e that they were designe r lateradfo l communication e alonWall th e lin f th go .e From Croy Hill East,r fo example, there is an uninterrupted view of Bar Hill fort, 1 mile to the W., interpolatioe th d an thin i s distanc secona f eo d expansion, Croy Hill West, only 150 yds. away from the first, is incomprehensible in relation to any lateral system of signalling. Similarly, Bonnyside East is not suitably placed to bridge the gap between Bonnyside West and the fort of Rough Castle, while rising ground screens Tentfield East from Tentfield West. Thus the expansions must be interpreted not as local exchanges, transacting normal

Fig. 5.

day-to-day business,2 but as trunk exchanges built to receive and transmit urgent messages over long distance exceptionan o s l occasions r sucFo h. purpose e mosth s t effective instrument Roman i e us n n i stime s were eth fixed beacons compose straf do kine logswr th o df o ,depicte Colume th n do n of Marcus Aurelius: a simpl d an 3e code coul operatee b d employiny db g them either singly or in combination. In the case of the Bonnyside and Tentfield expansions, which have no great outlook to the S., attention was obviously focusse e forwarth n o dd area d particularlan , e outposth n yo t forts guardin e Stirlingth g gapCroe Th y. Hil e othel th pair n r o ,hand , t onlno y enjo extensivn ya e prospec W. t d alsNe bu an ,.oth commano t d a magnificent view of the Clyde valley to the SW. It can hardly be a coincidence that this is the most easterly point on the Wall from which such a rearward vie ws obtainablei t doei t requird no s an , e muche efforth f o t imaginatio picturo nt e urgent warning nativf so e uprisings being relayeo dt Rough Castle or from the forward troops in Perthshire, trans- mitted thence alon Walle gquicklth d an , y dispatched south-westwardy sb means of the balefires on Croy Hill to arouse the garrisons of Clydesdale.

1 RWS, 356-8. pp . Such local exchanges, correspondin turrete th o Hadrian'gn t so s Wall, must surely have existen do 2 e Antoninth e Wall t nonbu , e r beehavefa no s found . 3 Cf. RWS, PI. LX. 2 , EXPANSION E ANTONINTH N O S9 16 E WALL.

APPENDIX. Details of the six known expansions are as follows: 1. Tentfield East.—Situated in Tentfield Plantation, three-quarters of a mile B. of Rough Castle fort and 160 yds. W. of Lime Road.1 It measures about 32 ft. from E. to W. at the Rampart face by 18 ft. from N. to Si, and is 3 ft. in height. It has not been excavated but the top is disfigured b ylarga e hole wher treea bees eha n uprooted. 2. Tentfield West.—Situated 650 yds. W. of Tentfield East and 40 yds. E. of the mineral railway line.2 It is barely discernible today, but would seem to be identical with the "Gilmor-seat castellum or watch-tower" mentioned by Roy, and represented in one of his plans as a small square earthwork abutting on the south face of the Rampart and measuring about 18 ft. each way.3 Gordon describes it as an "Exploratory Tumulus . . . only 15 ft. square." 4 . Bonny3 side East.—Cf. supra, . 162-6pp . 4. Bonnyside West.—Situated fore f Roug th o hal t f o mila f . h eW Castl d ean just insid e groundeth f Bonnysido s e House. t I measure5 s . abouft 0 3 t from E. to W.6 by 21 ft. from N. to S. and stands to a maximum height of t beeno ns excavatedha inst 6 I . . 4ft . 5. Cray Hill East.—On the westernmost summit of Croy Hill.7 It measures about 50 ft. from E. to W. by 30 ft. from N. to S.8 A section cut through it at the end of last century, and which still remains open, showed that the turfwork was laid on a rough stone foundation measuring 18 ft. across from N. to S. The transverse measurement was not ascertained, nor was the groun de foundatio plath f no n determined maximue Th . m heighe th f o t expansion was 5 ft. 6 ins., and it was concluded that the Rampart had been erected first and the expansion added subsequently, though probably after onl yvera y short interval.9 6. Croy Hill West.— e Onwesterth n f Croyslopo . f Croo eW . y ft Hill2 44 , Hill East . contour.jusd ft an t0 belo40 t measureI e 1w0th s abou fro. ft m0 t5 e Antonineth r sectioa fo d S.o . t t froan ft , . n cu Wallm0 N 4 , y b . W o t . E Report showed tha , beetood it t ha ,n addeRampare th o dt t soon aftee th r latter had been completed. In this case, however, the turfwork rested directly on the living rock.11

1 Nat. Grid ref. NS/855798; O.S. 6-inch map, Stirlingshire Nxxx NW.; RWS, PI. LIX. 2 , t "10No 20 yds. states a " d in RWS, . 352p . Nat. Grid ref. NS/850799; O.S. 6-inch map, Stirling- shire Nxxx NW. 3 Military Antiquities, 163 and PI. XXXV. • Itinerarium Septentrionale, 69. 5 Nat. Grid ref. NS/834798; O.S. 6-inch map, Stirlingshire Nxxix NE. 6 This measuremen onls i t y approximat junctioe th s ea nconceales i wit . Rampare E h th e th d n o t at the present time by a thick clump of rhododendron bushes. 7 Nat. Grid ref. NS/728762; O.S. 6-inch map, Dunbartonshire Nxxv. mSE hillOwin e slope exace th th th ,f eo o g t fallelimite th f nso turfwor noe kar t sharply dennee th t da presen8 measuremente t timeth t bu , s Antoninee giveth n i Wall Report (77) exaggeratede seeb mo t . 8 AWR, section 11, 77-9. 10 Nat. Grid ref. NS/727762; O.S. 6-inch map, Dunbartonshire Nxxv. mSE 11 AWR, section 12A, 84-5, and PL I.