Reasons for Designation
Roman and medieval flood defences were barriers designed to prevent the
inundation of land by salt or freshwater floods, and to assist in the
reclamation and drainage of large areas of low lying land. They normally
survive as a low elongated earth bank with a ditch on the landward side. The
banks were made of local clay or turf and were sometimes strengthened by
internal wooden frameworks, wattling or stone facing. Regular repair of flood
defences meant they often had a long life span of many hundred years with some
medieval embankments still in use today. Unaltered examples, ie surviving
medieval defences not subsequently reused in the post-medieval period, are
comparatively rare, and Roman examples rarer still. Flood defences are one of
a small number of Roman and medieval monuments to show the effects of man on
water control. Their longevity and their influence on the layout and pattern
of large areas of low lying land all contribute to their importance.
Details
The monument includes a section of medieval causeway known as Balt Moor Wall
located on the Somerset Levels north west of the River Tone.
The Balt Moor Wall was originally constructed as a causeway and subsequently
utilised as a flood defence barrier. It survives for approximately 550m as a
raised embankment above the surrounding low lying ground between East Lyng to
the west and Athelney Hill to the east.
Broadly aligned from east to west the causeway begins at the eastern edge of
East Lyng at the junction of Cutts Road with New Road. The western section of
approximately 300m is overlain by Cutts Road and here its north face rises
steeply to 4m high above ground level. The south side of the causeway is
overlain by a gently south sloping bank with an average width of 8m which runs
parallel with the road for approximately 180m. The causeway and road divide at
about 15m south east of Moorside, where the road turns sharply to the south
and then progresses eastwards. The raised causeway continues to the north east
for approximately 50m before curving to the east and gradually petering out
below the slope of the west side of Athelney Hill. This section of causeway
varies in width between 6m and 10m wide and in height between 1.7m and 2m
high.
An investigation programme into the stability of Balt Moor Wall carried out in
1996 confirmed the medieval phase of the causeway's construction which is
formed by an earthen clay bank of at least 6m wide at its base and 1.7m high
above the surrounding medieval ground level. Pottery recovered during the
investigation provided a 14th or 15th century date. The earliest known
medieval mention of the causeway comes from a charter signed by King Stephen
between 1135 and 1154 in which he refers to work carried out by the monks of
Athelney Abbey as part of land drainage and reclamation of the levels and
moors. The monument may be even earlier however. Balt Moor Wall causeway
links the fortified burhs of Athelney, a stronghold established by King Alfred
in 878 and Lyng, which is referred to in the Burghal Hideage, a list of
fortified burhs which dates from the early 10th century. Contemporary
documents refer to a causeway or bridge which connects the two burhs. A course
of laid stone rubble located at 3.2m below the present ground level in the
1996 investigation may be the remains of the Saxon causeway or bridge to which
these documents refer. Environmental samples taken from under the medieval
bank in 1998 were of a 5th to 7th century date which substantiates the case
for an earlier Saxon structure.
The 1996 investigation also revealed that the medieval bank had later been
clad with roughly coursed stonework which appears from the different bonding
mortars used to have been laid in two separate phases. These two phases almost
certainly relate to documentary records which refer to work on the causeway:
firstly, in 1675 when an order for the bank to be faced with stone was
recorded in the Quarter Session Records; and secondly in 1880 when the
causeway was encased in masonry at the direction of the Somerset Drainage
Commissioners.
Included in the scheduling is the clay embankment which overlies the eastern
end of the causeway for approximately 120m which was constructed as an
emergency flood control measure in 1994 and acts as a protective barrier.
All fencing, gates and gateposts, road surfaces, roadside bollards, kerbing
and hard-standing, telegraph poles, sluice gates and all post-medieval
structures not directly related in offering protection to the core of the
medieval wall are excluded from the scheduling, although the ground beneath
these features however is included.
Legacy
The contents of this record have been generated from a legacy data system.
Legacy System number:
33709
Legacy System:
RSM
Sources
Books and journals Other
Legal
This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Culture, Media and Sport.
End of official list entry
