Details

The monument includes the buried and earthwork remains of Offa's Dyke,
460m west of Glyn Farm. Offa's Dyke generally consists of a bank up to 3.5m
high with an intermittent ditch to the west and quarry ditches to the
east. In places Offa's Dyke was strengthened by additional earthworks,
namely a berm between the bank and ditch, and a counterscarp bank on the
western lip of the ditch.
In this section, the Dyke runs for some 579m, and is visible as a terrace
with a berm to the west and quarry pits to the east. The hillside across
which the Dyke runs is exceptionally steep, and the berm marks an
artificial break in the slope, allowing the terrace to form a false crest
to the slope. The berm is between 4m and 6m wide, and the terrace stands
approximately 4m above it. To the east of the terrace and berm, the
quarry pits have been dug into the crest of the hill and are up to 1m
deep, and between 4m and 8m wide.

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

Source: Historic England

Reasons for Scheduling

Offa's Dyke is the longest linear earthwork in Britain, approximately 220km,
running from Treuddyn, near Mold, to Sedbury on the Severn estuary. It was
constructed towards the end of the eighth century AD by the Mercian king Offa,
and is believed to have formed a long-lived territorial, and possibly
defensive, boundary between the Saxon kingdom of Mercia and the Welsh
kingdoms.
The Dyke is not continuous and consists of a number of discrete lengths
separated by gaps of up to 23km. It is clear from the nature of certain
sections that differences in the scale and character of adjoining portions
were the result of separate gangs being employed on different lengths. Where
possible, natural topographic features such as slopes or rivers were utilised,
and the form of Offa's Dyke is therefore clearly related to the topography.
Along most of its length it consists of a bank with a ditch to the west.
Excavation has indicated that at least some lengths of the bank had a vertical
outer face of either laid stonework or turf revetment. The ditch generally
seems to have been used to provide most of the bank material, although there
is also evidence in some locations of shallow quarries. In places, a berm
divides the bank and ditch, and a counterscarp bank may be present on the lip
of the ditch.
Offa's Dyke now survives in various states of preservation in the form of
earthworks and, where sections have been levelled and infilled, as buried
features. Although some sections of the frontier system no longer survive
visibly, sufficient evidence does exist for its position to be accurately
identified throughout most of its length. In view of its contribution towards
the study of early medieval territorial patterns, all sections of Offa's Dyke
exhibiting significant archaeological remains are considered worthy of
protection.

The section of Offa's Dyke in Highbury Wood, 460m west of Glyn Farm,
survives well, and illustrates the use of natural topography to enhance
the form and visibility of the Dyke. The terrace will have preserved part
of the original ground surface, predating the construction of the
monument and, along with the berm and quarries, will contain environmental
evidence in the form of organic remains which will relate both to the
Dyke and to the landscape within which it was constructed. The terrace
will also contain evidence relating to the methods of construction and
the building materials used.

Source: Historic England

Sources

Books and journals
Hoyle, J, Vallender, J, Offa's Dyke in Gloucestershire: Management Survay, (1997)

Source: Historic England