Summary
Culverts and part of a causeway, a continuation of the Grandpont (a Norman causeway), preserving the medieval and possibly Saxon southern approach to Oxford.
Reasons for Designation
The west and east Stanford Bridge culverts, Redbridge culverts 1 and 2, the west and east Mayweed culverts, the Lesser Mayweed culvert and those parts of the causeway above each are scheduled for the following principal reasons:
* Rarity: they are a continuation of the already scheduled Grandpont and represent an example of a medieval causeway (possibly with Anglo-Saxon origins), few of which now survive in their original form;
* Survival: original fabric is visible in the culverts and will survive in those sections of the causeway above each culvert;
* Potential: no recent disturbance or archaeological excavation has taken place in the vicinity of the culverts and the causeway. There is therefore the potential for the recovery of archaeological information and environmental evidence relating to the causeway and the landscape in which it was built;
* Documentation: the causeway is considered to have its origins in the Saxon or Norman period and represents an important element in understanding the topography and development of early medieval and medieval Oxford. It is one of the few examples of this type of monument where both archaeological and documentary records are available.
History
Abingdon Road (A4144) runs south from Folly Bridge, on the southern edge of Oxford, to Redbridge further south. The road originally turned west to cross the Hinksey stream. This part of the Abingdon Road is now known as Old Abingdon Road, while Abingdon Road continues south. For 650m south of Folly Bridge Abingdon Road was built on top of a Norman causeway with more than 30 arches or culverts, called the Grandpont. The Grandpont is believed to be part of the ‘Great Bridge’ built by Robert d’Oilly who also built Oxford Castle in 1071, and the Old Abingdon Road, 1.4m to the south, is considered to be a continuation of this causeway and has seven culverts.
Single and multi-span culverts are structures of one or more arches supported on footings and abutments. They were constructed throughout the medieval period to carry a causeway allowing water to pass beneath, for the use of pedestrians and pack horses or vehicular traffic, crossing smaller rivers, streams and marshy areas, often replacing or supplementing earlier fords. During the early medieval period timber was used for such bridging structures, but from the C11 stone culverts became more common. Culvert arches may be pointed, semicircular or segmental. Where medieval culverts have been altered in later centuries, original features may be concealed behind later stonework, and timber structures may be preserved below the culverts. The causeway above the culverts may be of stone or earth.
Although a basic network of roads was already in existence as part of the Roman road system, new towns and communication needs led to the construction of an extensive network of new roads throughout England during the medieval period. This network, much of which has now been disturbed or obscured by the modern road system, included causeways, fords and bridges.
Old Abingdon Road approached Oxford from the south and provided a causeway over the Hinksey stream, a group of channels which are a tributary of the Thames. During the Iron Age and Romano British periods alluvial deposits formed a series of islands in the floodplain in the area of South Hinksey now occupied by Hinksey stream which is thought to have been traversed by bridges and fords in the mid Saxon period.
It is possible that the causeway on the line of the Old Abingdon Road may have its origins in the Saxon period since a Saxon crossing of the river in the South Hinksey area by way of two fords is referenced in charter evidence. Evidence for Saxon structures on the route of the Grandpont are also found north of Folly Bridge where a stone structure thought to be of mid-Saxon date has been interpreted as metalling of a crossing of the alluvial islands. Also north of Folly Bridge the timbers of a bridge were excavated and dated to between the mid-C7 and the early C10.
The Norman and medieval parts of the Old Abingdon Road culverts are, by comparison of materials and construction, contemporary with the Grandpont. These culverts with Norman and medieval phases have been extended and modified over time.
Cartographic evidence, from the New College Map of the Land in South Hinksey, a C16-C17 document, depicts the Old Abingdon Road with three round headed arches, and a road surface without a parapet. The road is labelled ‘The Bridge or Horse way from Oxford to Abingdon’. The round headed arches are thought to be the Stanford, Mayweed and Lesser Mayweed bridges. Thus these bridges, in their original state, probably date from the C16 or C17, but have been much repaired and modified. The Inclosure map of 1814 suggests two flood relief arches at Mayweed Bridge, and possibly a similar arrangement at Stanford Bridge. In addition another channel depicted is probably one of the Redbridge culverts.
The Great Western Railway Oxford to Didcot Branch Line was completed in 1844. The construction of a railway bridge which carries the Old Abingdon Road over the railway line involved building an embankment between the Mayweed and Stanford Bridges, and necessitated extensions to the Redbridge culverts, which lie just to the west of the railway bridge.
A Ground Penetrating Radar (GPR) Survey was undertaken by Waterman CPM in 2008 on areas of potential causeway survival, but this proved inconclusive. An archaeological investigation was conducted on the culverts in 2009 which was able to identify their date and fabric.
In 2011 a watching brief was conducted by Oxford Archaeology on the replacement of the old Abingdon railway bridge which extended to the carriageway either side of the railway bridge. Although work was done above the culverts, the depth of impact of groundwork did not extend to the culverts and only C19 and C20 deposits were affected
Details
The bridges and culverts on the Old Abingdon Road are, from west to east:
The Stanford Bridge culverts which lay either side of a main central bridge
Redbridge Culvert 1 or west
Redbridge Culvert 2 or east
Mayweed Bridge culverts over Hinksey stream which comprises two culverts to the east of a main bridge
Mayweed Lesser culvert
Each culvert has a number of phases of extension and modification. The spans of the culverts from abutment to abutment vary between 1.25 and 1.75m. The 2009 Archaeological Investigations Summary Report identifies the earliest phases of construction within each culvert as dating from the early medieval (Norman) to medieval periods and are described below.
STANFORD BRIDGE CULVERT
These comprise two culverts one either side of Stanford Bridge. The earliest phase of each culvert lies on its south side.
The western culvert is about 4m wide north to south and the pointed arch on its northern side is more compressed on its south elevation. The culvert has dressed stones on the abutments, a rubble stone vault and limestone voussoirs. Beyond this early phase the culvert is constructed of rubble stone.
The eastern culvert is 3.9m wide. It has radiating voussoirs with fine joints and a coursed rubble stone vault. The voussoirs on the north side are weathered suggesting that this was once an outside face. There is tooling on the abutments of the east side and evidence of repair and modification on both north and south elevation.
The remainder of the culvert has phases of squared blocks with mortar joints and rubble stone construction.
REDBRIDGE CULVERT 1 (WEST CULVERT)
The earliest part of this culvert, in two phases, lies in the middle of the culvert, flanking a later, narrow central section 1.65m wide. The earliest phase, 3.98m wide, is to the south of the centre of the culvert and has abutments extending from a stone footing 0.12m from the abutment face. There are two courses of masonry footings and the abutment above footing level comprises two courses of ashlar masonry with vertical striated tooling. Above this are two courses of rubble stone masonry which bear the springing of the barrel arched head of the culvert. The face of this section has limestone voussoirs and the head of the arch has longer and narrower blocks. The character of this part of the culvert is consistent with a positively identified Norman phase of the Redbridge 2 (eastern) culvert.
The second phase, to the north of the central section, is 3.2m wide and has squared abutments on a rubble stone footing. The rubble stone vault has limestone voussoirs.
REDBRIDGE CULVERT 2 (EAST CULVERT)
The earliest phase of this culvert is again in the centre of the culvert and is 3.8m wide with a span of 1.75m. This phase has been securely dated to the Norman period. It has large ashlar masonry blocks with diagonal striated tooling and fine joints. The arch follows a shallow arc from a low spring point and terminates in a round head rubble stone arch.
The remaining phases are of rubble stone construction.
MAYWEED BRIDGE CULVERTS
This comprises two culverts to the east of the main bridge span. The earliest phase of each culvert lies just to the north of the middle of each culvert.
The western culvert early phase, 4.1m wide, has large ashlar blocks abutments, rubble stone vaults and dressed stone voussoirs. Diagonal striated tooling was seen on the abutments and rubble stone vault.
The eastern culvert early phase is 4m wide and was identified as characteristic of the culvert construction of the Grandpont causeway. The barrel vault is of coursed rubble stone with voussoirs carved from shelly limestone and there is some striated tooling present.
The other phases of both culverts are of rubble stone construction without any dressings.
MAYWEED LESSER CULVERT
There are five phases of construction here, but the two earliest phases are the two central sections. The abutment of the southern of these two sections is partly encased by the northern section which indicates that the southern section is the earlier.
The southern section is 2.8m wide and has squared masonry blocks with fine jointing from the springing to the apex of the barrel. There are similarities between this section of the culvert and the culverts at the northern end of the Grandpont.
The northern section is 4.12m wide and has roughly squared and coursed block abutments and dressed stone voussoirs. Striated and coarse tooling was seen on some of the stones.
The other phases of the culvert are of rubble stone construction without any dressings.
It is considered that the earliest, Norman, phases of culverts along this part of the causeway are the first phase of Redbridge 1, the Redbridge 2 culverts and possibly the southern phase of the Mayweed Lesser and the eastern of the Mayweed Bridge culverts. The other phases of the culverts described above are of medieval date, but extensions beyond these are of a later date.
The 2009 Archaeological Investigations Summary also indicates that by comparison with the Grandpont the surviving causeway on top of the culverts is about 0.3m thick.
EXTENT OF SCHEDULING
The scheduling aims to protect the Norman and medieval phases of each of the culverts and the causeway above in each case. The maximum span (from culvert abutment to abutment broadly in the direction of the road) of the culverts is 1.75m, apart from the Mayweed west and east culverts which are so close together that it is more appropriate to include them in one area of archaeological protection which has a maximum span of 8m.
There are therefore six areas of archaeological protection: three of 4m wide (width is measured across the road) in the west and east Stanford Bridge culverts and in Redbridge Culvert 2; one of 9m wide in Redbridge Culvert 1, which includes the later central section of the culvert for ease of management; one of a maximum of 4.25m wide in the amalgamated West and East Mayweed Culverts respectively and one of 7m wide in the Mayweed Lesser Culvert.
As the causeway is considered to lie just above the culverts with a thickness of 0.3m, in order to protect the causeway and allowing for a 0.3m buffer to provide a margin for protection and maintenance of the causeway, the area of archaeological importance extends to 0.6m above the culvert soffits. In the case of the Lesser Mayweed culvert this will give very little clearance to the road surface as the distance from carriageway to soffit is 0.84 - 0.9m.
The tarmac surface and make-up of the road above the areas of archaeological importance is excluded from the scheduling but the ground beneath is included.
