Details

The monument includes a 500m-long section of the Grandpont causeway which
crosses the Thames floodplain to the south of Oxford.
The causeway is buried beneath the modern line of the Abingdon Road and is
encased in later widening and revetting. However, exposed sections of the
Norman stonework, forming several of the arches and piers which make up the
causeway, can be seen from the river beneath. The earliest phase of the
ragstone causeway was between 3.9m and 4m wide and was constructed as a
continuous linear structure with arches set along its length where river
channels or drainage needs dictated. Within the section of the causeway south
of Folly Bridge and north of White House Road there are eleven arches, six of
which are visible, while the rest have been filled in over the years. The
causeway has been widened on at least two occasions, giving it a modern width
of c.12.5m. It is likely that evidence survives for earlier Saxon or Norman
wooden bridges beneath the Grandpont, while it is known from excavation at 33
St Aldates that a Saxon ford, which preceded the causeway, went out of use and
silted up to the extent that by the late 12th century it was covered with
1.25m of accumulated silt. It is believed that the Grandpont is part of the
`Great Bridge' built by Robert d'Oilly who also built Oxford Castle.
The Folly Bridge, located midway along this section of the Grandpont, also
known as `Friar Bacon's Bridge', is a later medieval feature and included a
six-sided tower with portcullis, drawbridge and heavy gates which provided a
barrier to any enemy approaching the South Gate of the city along the
causeway. This was partially demolished and rebuilt in 1826 having become `so
decayed' by the time of Waterloo (1815) that it was no longer safe. The tower
foundations survive in the river bed. The bridge is listed Grade II.
In addition to the remains visible from the river, evidence for the survival
of the Grandpont has been provided by a number of excavations and observations
using existing manholes and during essential works on service trenches. These
have provided evidence that the structure survives along this 500m section and
beyond, although the majority of observations and the visible remains are
contained in this stretch. Although the original core only measures c.4m wide,
the preservation of the monument depends upon the entire width of the
carriageway (c.12.5m) being included in the scheduling. Excluded from the
scheduling are the 19th-century reconstructed elements of the listed Folly
Bridge, the modern road carriageway and its make-up as well as the drainage
culvert and all existing service trenches which run along the causeway,
although the ground beneath all these features and beneath and around the
service trenches is included in the scheduling.

MAP EXTRACT
The site of the monument is shown on the attached map extract.

Source: Historic England

Reasons for Scheduling

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.
The Grandpont represents an example of a causeway, few of which now survive in
their original form. Although this example has been obscured by later
alterations and additions, original fabric is visible from the river whilst
partial excavation has demonstrated the survival of substantial archaeological
remains beneath the modern road surface. The causeway is thought to have its
origins in the Saxon or early Norman period and represents an important
element in understanding the layout of early medieval and medieval Oxford. It
is one of the very few examples where both detailed archaeological and
documentary records are available.

Source: Historic England

Sources

Books and journals
Durham, B, 'Oxoniensia' in The Thames Crossing at Oxford: Archaeological Studies 1979-82, , Vol. XLIX, (1985), 57-
Durham, B, 'Newsletter' in Oxford: Abingdon Road and Folly Bridge, , Vol. 11, (1981), 129
Other
Colour prints taken from punt, SCHOFIELD, J., Field visit photographs from SM file, (1992)
Discussion of O.A.U. work on sites, JEFFERY, P.P., Discussion between B. Durham and P. Jeffery, (1992)
PRN 6358, CAO, Folly Bridge, (1987)
Title: Plan of Folly Bridge and Granpont
Source Date: 1590
Author:
Publisher:
Surveyor:
Plan in Brasenose College Archives

Source: Historic England