Site Code. CHICHESTERGPR15Site identification

and addressChichester

County, district

and / or boroughChichester District Council

O.S. grid ref. ManyGeology. Alluvium over London ClayProject number. SNUFFLER1504Fieldwork type. Geophysics – GPRSite type.Date of fieldwork. July 2015Sponsor/client. CDCProject manager. David StaveleyProject

supervisor.Period summary Roman and Medieval

Project summary.

(100 word max)GPR survey over various parts of Roman Chichester

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A Ground Penetrating Radar Survey Targeting RomanChichester

by David Staveley

Contents

1. HER Statement2. Contents3. Introduction3. Acknowledgements3. Methodology4. Priory Park4. Positioning6. Results6. Area 18. Area 214. Area 319. Area 421. Area 1,3,4 Interpretation24. Area 2 Interpretation26. Conclusion27. Amphitheatre27. Positioning28. Results33. Interpretation35. Conclusion36. Single Transect Surveys36. Stane Street39. Town Walls42. Conclusion43. References

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Introduction

This project was initially started to answer a particular research question, which was whether or notStane Street continued on through Chichester and out of the south gate instead of stopping at theeast gate. This theory was put forward by John Magilton (1995B, p.31), who suggested that the roadpre-dated Chichester. The original plan was to walk along all of the pavements within the Romantown walls, taking single GPR B-scans and joining the dots to reveal the internal Roman roadlayout of the town. It subsequently became clear that the archaeology was too damaged and tooshallow for this to work well, so radar surveys of grassed areas at Priory Park and the Amphitheatrewere added to make the project more fruitful. Other areas received light attention with a view tocarrying out further radar work.

Acknowledgements

The author would like to thank James Kenny of Chichester District Council for making this possibleand for his expert local knowledge of the archaeology. This wisdom is hereafter referred to as JKPC(James Kenney Pers. Comm.)

Methodology

The surveys shown here were carried out using an UTSI Groundvue 3a ground penetrating radarwith a 400MHz antenna. A-Scan separation is ~3cm and line separation varied between surveyareas. The data was processed using ReflexW, with static correction, background removal, gain andband pass filters applied. Depths given assume a velocity of 0.1m/s and are only a rough estimation.No hyperbola fitting has been done. Survey grids were set out and position recorded with a JavadTriumph-LS GNSS net rover. Any position given is OSGB36/OSTN02/Newlyn Datum. Ininterpretation images, possible Roman features are shown in green, possible medieval in yellow andpossible modern in red.

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Priory Park

Two areas of the park were surveyed, the large cricket pitch to the east (Area 2) and the smallertriangular area of grass to the south of the Guildhall (Area 1). Since the area was so large, a lowresolution exploratory survey was undertaken with lines spaced one metre apart and walking east-west, with a view to surveying areas again at a higher resolution if something interesting was found.Two further areas of interest (Areas 3 and 4) south of the town hall were then surveyed with 25cmline spacing when Roman buildings were found for a total of four survey areas. Select time slicesare shown to display the features discussed in the interpretation.

Positioning

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Area Pos Easting Northing

1 Size 50m 55m

A 486195.80 105104.38

B 486245.74 105106.49

C 486248.07 105051.56

2 Size 120m 130m

D 486253.83 105151.86

E 486353.29 105166.08

F 486258.90 105032.00

G 486378.77 105037.07

3 Size 25m 30m

H 486213.08 105098.11

I 486238.05 105099.16

J 486214.35 105068.14

K 486239.32 105069.20

4 Size 25m 20m

L 486222.68 105060.49

M 486247.65 105061.54

N 486248.49 105041.57

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Area 1 Results

Area 1 – 16.6ns (~83cm)

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Area 2 – 20.7ns (~103.5cm)

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Area 2 Results

Area 2 – 10.5ns (~52.5cm)

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Area 2 – 11.9ns (59.5cm)

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Area 2 – 13.1ns (~65.5cm)

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Area 2 – 15ns (~75cm)

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Area 2 – 16.4ns (~82cm)

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Area 2 – 24.2ns (~121cm)

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Area 3 Results

Area 3 – 13.7ns (~68.5cm)

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Area 3 – 19ns (~95cm)

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Area 3 – 22ns (~110cm)

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Area 3 – 27ns (~135cm)

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Area 3 – 30.5ns (~152.5cm)

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Area 4 Results

Area 4 – 11.4ns (~57cm)

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Area 4 – 17ns (~85cm)

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Areas 1,3,4 Interpretation

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A) This feature, clearly visible on aerial photographs, is a modern reservoir (JKPC). It is visible inthe slices from the surface and the walls slope inwards slightly until it disappears at about a depth of60cm.

B) This building appears to be a Roman town house. The highest upstanding sections of wall, on theeast and north side start to make an appearance at 30cm, and intact floors to the south-west at 35cm.One room appears to have a complete floor and three other rooms surrounding it have partial floorspaces remaining. A full set of foundations don't appear in the slices until about 85cm, so thereseems to be significant robbing of the walls, especially in the north where some walls have gonecompletely. The whole building probably extended further to the west, but will have been truncatedby feature A.

C) This feature appears to be in very good condition, probably due to its depth. The highestremaining wall parts are at 45cm, lower than building B by 10cm, but the rest of the building issunken, with the completely intact floor not making an appearance until a depth of 90cm. This floorslopes downwards from the south to the north by 20cm. This slope is consistent rather than warped,so may be down to design rather than post Roman sinking of the feature. The wall appearing to cutthe building in half is only about 10cm high at the bottom, with the surrounding untouched wallsextending much higher, so again this may be down to design rather than robbing. The smallextension to the west may be access down into this room from the Roman surface level, but stepsare not visible on the results. The building seems to be connected to building E to the south, both bya wall and the same orientation. The most likely interpretation is an unheated bathing pool.

D) This flat section of hard material may be a collapsed section of Roman wall, perhaps preservedas other upstanding sections were more obvious targets for stone robbing, with this section covered,but due to a lack of foundation at this point, a more likely explanation is that this is a medievalfeature associated with feature G, constructed of robbed Roman material. The blue line on theinterpretation is the line of the transect shown below. Feature D is shown to the centre left, with thecut of feature G showing weakly diving down next to it, before rising again to another small solidfeature to the east that is on the same level as feature D. The three seem associated in this transect,hence the suggestion that they are of the same date.

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E) Another possible Roman building, connected to building C by a wall. It is not in as good acondition as building B. The highest surviving sections of wall appear at 30cm, the centre wallrunning N-S. Most of the walls in the northern part have appeared by 50cm and the southern part by60cm. There are no surviving floor layers.

F) This small circular feature is bowl shaped. It appears at 35cm, being ~140x190cm wide curvingdown to a base ~80cmx110cm wide at a depth of 50cm. It's purpose is unclear. A transect across thisfeature, shown by the blue line on the interpretation, is shown below, with feature F in the centre.To the east of that, some of the rubble filling the cut of feature G is visible.

G) This feature is most likely the same as feature J in area 2, but here is more visible, as the fillcontains some solid material. Due to the proximity to building E, this solid material used forbackfilling this feature may be wall and floor material robbed from feature E. The feature seems toend abruptly at feature D, which may be associated with it, but this is not a certainty, given feature Jin area 2 is so hard to see. What is not visible in area 1 to the north of feature G is the same phasechange in the un-enveloped data that defines feature J in area 2. The profile looks curved to thenorthern end, as shown on the transect associated with feature D, while to the south the cut seemsalmost vertical, as shown on the transect associated with feature F.

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Area 2 Interpretation

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A & B) Features A and B were originally part of the Roman street grid of Chichester. It is roughly6.5m wide to the north and 8m wide to the south, but were once the same feature, being cut by themedieval motte ditch, feature E. To the south, it seems it is also cut by feature H. The whole is onthe same line as a previously known road that heads roughly along the line of Little London (Down1988 p.15). Also to the south, there is a 3m wide branch road heading east, perpendicular to themain street for a distance of roughly 17m. These features appear in some form almost from thesurface, and are visible as parch marks in dry weather, though the most solid parts start at a depth of25cm. Further, less solid material, on the line of the road is visible almost to the surface. At depth,the road can still be seen at around 70cm. Feature B is partly cut by feature F, plus there are twofurther cuts on the east side of A and B which are either down to robbing or Saxon occupation.

C) Nestled within the corner of two Roman connecting Roman roads, this thin layer of solidmaterial starts at a depth of 35cm at the eastern end and slopes down to the west to a depth of 45cm.It may be an area of hard standing. There don't appear to be any further features associated with it.

D) At the north end of the site, near the remains of the motte, is a collection of features east andwest of the Roman street that are marked as Roman, but the date is not completely clear. Theyappear mostly at a depth of 40-70cm and consist mostly of amorphous masses of loosely packedsolid material. An east-west headed linear feature at the same depth, apparently cut to the east bymedieval feature E is perpendicular to the Roman road at feature A. It is not particular wide, but itstrue width is not clear as it was parallel to the 1m spaced survey lines. At the southern extent ofthese features are four linear features that look more consistent with Roman occupation. As a whole,they may be low status Roman period occupation, Saxon or even later. They are unlikely to bemedieval, as they would be under the extent of the motte before its later post-medieval removal(JKPC).

E) This is most likely the ditch around the medieval motte (JKPC). The contrast is very slight and ismore visible on the eastern side compared to the west. It can be seen from a depth of 10cm slopinginwards and can still be just about seen at a depth of 1m, but as a feature, it is no doubt a lot deeper.At depth, it is most likely silted up, with some loose rubble or refuse in the top layer providing theslight contrast visible. The feature appears to cut Roman features A, B and G, plus the linear fromthe eastern part of D. It varies in width from 18-29m. It's placement confirms the parch mark notedby Magilton (1995A p.25).

F) These two thin, parallel linear features, composed of reasonably solid material, appear at a depthof 90cm. Projected to the NNE, both features can be seen to cut the Roman street, feature A, withthe western feature showing a very slight amount of solid material extending along the length of thecut. They have roughly circular counterparts to the SSW almost to the other side of the medievalditch. All four features possibly comprise the foundations for the medieval bridge across the motteditch. The features extending back to the NNE suggest both that bridge could be raised,necessitating a more complex cut on the north side, and that the motte, before it was mostlyremoved, probably did not extend as far as the motte ditch, leaving a berm between the two. Theoriginal extent of the motte is not visible on the radar.

G) This narrow linear feature, about 1.4m wide, is most likely Roman. While not on the samealignment as feature B to the east, it is well constructed in the same manner as B, is at the samedepth and is cut by features E and H in the same way as feature B. A possible small building lies tothe west at a depth of roughly 50cm.

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H) There are several possible medieval (JKPC) features in this area. The most obvious is a wideditch filled with solid material from a depth of 10cm in the very SE corner of the survey area,sloping down to the SE. Further areas of slight contrast are visible adjacent to it to the NW,associated with short lines of what appear to be post pads, 1.5m apart for a palisade. These aren'tvisible for a great distance to the west, but suggest that there are several phases to the defences here,which seem to post date and are contained by the original outer bailey cut, feature J.

I) This thin feature is probably a modern pipe used for watering the cricket pitch.

J) This line may mark the rough northern edge of the main outer bailey ditch cut. It is only visibleas a phase change on the un-enveloped data, having little in the way of amplitude contrast. Thevarious features described in feature H may post date this and represent later versions of thedefences. This feature is responsible for the truncation of Roman features B, C and G. Its width issimilar to feature E and is visible extending to the strongest feature of H to the south-east but isunclear to the south and south-west. Its width to the west is probably lessened, as it doesn't seem totruncate the villa in area 4. Its depth is not clear, but it is visible from the surface and reaches atleast 1.2m below the surface. The lack of contrast on the radar may be down to silting or backfillingwith clean soil.

Conclusion

The high status Roman occupation to the south-west may reflect its closer proximity to the centre ofthe Roman town, with possible lower status activity out towards the walls to the north. Thecondition of the buildings varies, but there are some floor levels left, plus small sections ofupstanding wall. The nature of the low status occupation to the north is not clear and would benefitfrom a further higher resolution survey than the 1m exploratory survey undertaken. The largestmedieval features associated with the motte, the ditch and bridge, are fortunately clear, but not themotte itself. The motte probably doesn't extend as far as the motte ditch. The bailey defences areless clear and further work is needed at a greater resolution. Where the bailey ditch is more visibleas feature G in area 1, the width of the feature has become a lot narrower than at feature H in area 2.It may be that the Roman ruins were still partially upstanding at the time, making an earth cut lesseasy.

Due to the excellent quality of these results, surveys in further grassed area, especially in the south-west quadrant of town, may be fruitful, especially close to the centre of town, where the higheststatus buildings seem to be concentrated.

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Amphitheatre

Chichester Roman amphitheatre remains as a low earthwork to the south-east of the east gate. Earlyexcavations (White 1936) showed there was potential for revealing the structure using radar. Asurvey was undertaken walking WSW-ENE with 0.5m line spacing. Select time slices are shown todisplay the features discussed in the interpretation.

Positioning

Pos Easting Northing

A 486653.24 10460248

B 486607.43 104691.37

C 486669.66 104723.43

D 486715.46 104634.54

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Results

1.7ns (~8.5cm)

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6.1ns (~30.5cm)

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14.2ns (~71cm)

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16.5ns (~82.5)

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20.1ns (~100.5cm)

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Interpretation

Red features are solid modern, orange are modern surfaces, yellow are modern cuts, dark green aresolid Roman and light green are less solid Roman features.

A) A modern pipe cuts across the site parallel to the modern path. It is 45-65cm below the surface,and its cut can be seen at higher levels as a lower amplitude response feature cutting through amessy higher amplitude response topsoil. For part of its journey, it is joined by a second pipe, whichthen seems to branch off, north into another cut, feature D, but now lacking a pipe, apart from at itseastern end.

B) The modern path, still metalled.

C) This structure is a late 19th/early 20th C farm building (JKPC) but the solid layer, in orange, isquite thin. It is probably an area of hard standing. Its northern end may be associated with the roadto the east, which is perhaps now truncated. The gap may be where a building once stood, with apath around the outside. If such a building existed, it did not have solid foundations. The cut featureleading into the blank area may have been where a utility or utilities entered the building. Thewhole is probably modern. Features A and D both cut the area, and where feature A meets feature C,its course changes, suggesting they are from roughly the same period.

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D) This cut shows as a lower amplitude linear feature running parallel to features A and B. It isprobably a modern pipe trench, but the pipe has since been removed, except under feature C andadjoining feature A after it turns to meet that. There are further short cuts perpendicular to thisfeature that stop when they hit features A and B.

E) This thin layer of hard material leading from the modern path, feature A, is most likely a moderntrack leading to buildings to the north.

F) These are the footings of modern playground equipment, since removed (JKPC). Thenorthernmost is 3.5m x 6.5m, with an extant surface and seemingly three supports for theplayground equipment. The southernmost one, which looks similar to the first, has no solid floorsurface.

G) This is the floor of the Roman amphitheatre. Its response is very slight and it probably extendsmuch further than shown. It is closest to the surface at the centre, where it is 30cm below theground. The ground rises very slightly as it heads towards the edge of the amphitheatre and theweak response slowly disappears until it is last seen about 1m down, roughly two thirds of the wayto the edge of the amphitheatre. The area shown merely gives the shape on one time slice to showthe rough shape of the feature in relation to the rising ground.

H) These areas are the main bank of the amphitheatre structure. There are few hard edges, with thewhole being composed of a material containing fragments of material producing a slightly higheramplitude response. Some edges are difficult to discern, so the areas shown should be a guide onlyto the overall shape. Two entrances are visible leading through this feature to the east and north,with the eastern entrance seeming to have far less importance than the northern one. It is not clearwhether further cuts in the eastern edge of the feature are part of the design or modern disturbance.The depth of the feature is certainly undulating, but as height data is not recorded, the full verticalstructure is not clear. The highest visible part is 20cm below the surface, but may be higher, gettinglost in modern material.

I) One of the few areas of wall visible, this structure makes up part of the northern entrance. Thesouthern part is the western retaining wall of the entrance, with the northern part seeming to makeup a small room, 5m x 6m. The highest part is only 20cm down.

J) This feature is the retaining wall on the east side of the northern entrance. Its highest part is 40cmdown and it is probably mostly robbed given feature K is visible slightly higher.

K) This thin layer of material seems to be a barely metalled track heading into the amphitheatrethrough the north entrance. Its highest part is visible 35cm down.

L) This is the only surviving part of the inner retaining wall, starting roughly 40cm down. It is inthe correct position as compared to the sections of wall found in the early excavation (White 1936,p.151). That this is the only part surviving suggests that much more of this feature was robbed afterthe excavation occurred.

M) This very solid feature may be a metalled surface. It is visible at the surface, but also over ametre down. There is a hint that it may have once continued on, curving slightly to the east, but thisis not shown on the interpretation. It is marked on the interpretation as Roman because of the extentof the depth of it, but it is also possibly a modern feature, given how close to the surface it is found.

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Conclusion

The amphitheatre is in fairly poor condition. Most of the retaining walls have been robbed and thebulk of the materials of the bank have slumped outwards, both inside and out. There is a lot ofmodern activity at the surface, most of which is not shown on the interpretation, including theoutlines of rectangular allotment plots (JKPC), parallel to the path, that are only visible on the un-enveloped data. The north seems to show a significant entrance, more significant than the one to theeast, but as the western and southern entrances are not visible, it is difficult to say whether or not itis the main entrance. The trackway leading from it certainly heads towards Chichester, so it is agood candidate. The early excavation (White 1936, p.151) showed four sections of wall in varioustrenches. The southernmost section seemed to be outside their projected line for the interior of thebank, but the radar shows the bank extending further to the south than is suggested by their line, andthat fourth section of wall is indeed on the same line as the other three. This may mean that theamphitheatre is slightly more elongated than previously thought.

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Single Transect Surveys

Stane Street

The original reason for coming to Chichester was to test John Magilton's theory (1995B, p.31) thatStane Street continued south-west through Chichester, out of the south gate and on to a possible portat Dell Quay, the inference being that the road came before the town. The problems with findingthis road are obvious, but it was hoped that single radar transects along the roads, pavements andcar parks would yield some evidence of the road below. This approach has met with some successalready, with the camber of Stane Street as it crosses under Church Street, Ewell visible on thetransect below.

Stane Street, under Church Street, Ewell

This approach would not be a guaranteed success in Chichester. Utilities had the potential to wreckarchaeology and clutter any results. Much of the archaeology may have been robbed. The surveys inPriory Park showed that the Roman layers are very close to the surface, so would be sitting amongstmodern material, making features difficult to recognise. The best potential is in car parks, whichwould have less in the way of modern disturbance than pavements or roads. The image belowshows transects recorded in red. Due to the urban canyon, it was difficult to take reliable GPSreadings, so the lines are approximate.

Possible cambers are shown in green, with parts of the transects numbered shown below, all in carpark areas. The most convincing are sections 14 and 24, but even these are sketchy compared to theexample from Ewell. None of them are on the projected line of Stane Street, and they vary in width.They may be part of the internal road network of the Roman town, or something modern with asuitably cambered shape. It should be stressed that these results prove nothing and are merely anindication that something of interest may be there. Full 3D surveys of these car park areas mayresolve what these features are.

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Transects across the south-east Quadrant of Chichester

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Section 14, east to west

Section 16, south to north

Section 17, north to south

Section 24, west to east

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Town Walls

There has been recent research using earth resistance to map lost bastions around the south-westedge of the Roman town wall. One such bastion, clearly visible on the earth resistance also showedclearly on a radar transect, section 1. This is the signature that would pinpoint other bastions aroundthe walls, both on grassed areas, and potentially under modern pavements. Three additionaltransects were taken, as shown in the diagram below, to see if this approach was viable. Section 2,to the east of section 1 showed a wide area of solid material at the eastern end. It is of interest, but isnot a bastion. Section 3, along the western wall, showed nothing of interest. While in the area, theBishop's Palace Gardens were scanned to evaluate their archaeological potential without recordinganything. Label A in the diagram below shows the possible location of a feature of interest, but it isa single point and may be nothing. Label B is the rough location of something more substantial.Two possible walls and a possible floor surface were visible when scanning.

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Section 1, west to east

Section 2, west to east

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A further transect was recorded adjacent to the north east part of the town wall, again to look forsigns of a bastion. While no bastions were spotted, there was one other feature of interest in section4. Under the modern material was a very wide feature with a V shaped profile. It looks like a rubblefilled cut, almost 10 metres wide. One possible explanation for this feature is the 1st centurydefensive ditch projected to this point from the cattle market to the south (Down 1988, p.24). Thatfeature was 7m wide. The extra width here may be accounted for by the transect crossing the featureat an angle. The depth of this feature and excellent response from its reasonably solid fill may meanthat it would be traceable for some distance.

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Section 4, south to north

Conclusion

Radar is useful for quickly scanning for larger features such as bastions and defensive ditchesaround the town walls. The possible first century ditch warrants further work, but there is limitedscope for finding further bastion foundations due to the fragmentary nature of the spaces where aradar could be run.

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References

Down, Alec, 1988, Roman Chichester, PhillimoreMagilton, J.,1995A, Chichester Castle Reappears, The Arch. Of Chichester & District 1995Magilton, J., 1995B, Roman Roads in the Manhood Peninsula, The Arch. Of Chichester &District 1995White, G.M., 1936 The Chichester Amphitheatre: Preliminary Excavations, Ant. J.16 (2)

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