Reasons for Designation
The industrial complex at Kimmeridge Bay is of principal significance for its
alum works, although the adjacent glass works and salterns add to the
importance of the site.
Alum is a chemical used principally in the textile industry for fixing dyes.
It is not found in a natural state in Britain, but can be manufactured from
some types of shale. During the medieval period in Britain alum was imported,
mostly from Italy, while domestic production began in the north of England in
the early 17th century. The industry flourished in the north for 200 years
until the mid-19th century when it was overtaken by new techniques using shale
from coal mining, whilst after 1880 aluminium sulphate replaced alum for most
industrial purposes. The last English aluminium works (at Goole) closed in
1950. Approximately 50 alum sites have been identified in England. Most were
along the Cleveland and Yorkshire coast. Other sites are known along the south
coast, particularly in Dorset and Hampshire.
Alum works comprise two main components: the quarry where extraction and
initial processing took place, and the alum house where final processing took
place. Alum shale was extracted from quarries situated on steep inland
hillsides or coastal cliffs. Initial processing on the quarry floor consisted
of clacination by burning shale in clamps, and the production in settling pits
of alum liquor. The liquor was transported to processing works in sealed casks
or through wooden channels known as liquor troughs. Larger quarries possessed
inclines and haulage gear and sometimes harbour facilities. Stores, workshops
and laboratories can also survive. Evidence of secondary industries such as
epsom salts and iron silicates production is also preserved at some alum
works.
The alum industry was the first chemical industry in Britain. Its quarries and
works illustrate the early stages of the industry and the technological
advances through the period known as the Industrial Revolution. The alum
industry also provides information about wider changes in social and economic
conditions during this period. The large scale of the industry's workings also
mean that its remains are today a major component of coastal landscapes. A
sample of the better preserved sites, illustrating the regional, chronological
and technological range of this class of monument, is considered to merit
protection.
Glass has been produced in England since the Roman period, although field
evidence for pre-medieval manufacture is scarce. Glass production requires
three major ingredients: silica, alkali and lime, but the most important
requirement was fuel. From the 13th century to about 1610, the glass industry
used wood as a fuel and workings were sited in or close to forests, where
coppicing was conducted. The industry appears quite widespread, but the Weald
area of Sussex and Surrey and the south Staffordshire areas represent the
major centres of production. During the late 16th century the industry was
expanded and areas such as Gloucestershire, Hampshire, Herefordshire,
Lancashire, Shropshire, Warwickshire, Worcestershire and North Yorkshire
became more significant. The most important factor was the availability of
woodland, although proximity to the markets of the larger cities such as
Bristol and York was also significant. The English industry was unique in
Europe, in that during the period 1610-1620 the glass industry had a sudden
and total change to the use of mineral fuel. This brought about a shift in
location and the industry then remained closely connected with coal fields
until recent years.
Salt is of primary importance in the preservation of food and has been an
integral part of the north European economy since prehistory. Sodium chloride
(the main component of table-salt) occurs in solid form as rock-salt (halite)
or in solution as brine. Salt has been extracted from seawater on the English
coast since at least the Bronze Age. It formed a major industry along parts of
the coastline in the Roman period and also formed an important product during
the Middle Ages, when salt was exported from east coast towns to other parts
of Europe. Evidence for saltworking along the coast of southern England during
the Iron Age and Romano-British periods is quite widespread, although this was
restricted by the need for a suitably high saline content within the water
supply, and a source of fuel for burning and clay for equipment used in the
extraction process. Two main groups of sites have been identified along the
Dorset coast, the first around Poole Harbour and the second around Kimmeridge
Bay.
Despite some coastal erosion to the south, the alum works, other multi-period
industrial remains and the associated group of breakwaters and jetties at
Kimmeridge Bay survive as a combination of earthworks, accumulated deposits,
structural foundations and buried features. These contain archaeological
deposits and offer considerable scope for the study of the development of the
industries. The alum works represents one of the earliest examples of its
class and is one of few examples identified in England with potential for the
survival of 16th century remains.
The glass works at Kimmeridge is notable as it lies within an unusual area and
represents one of few sites identified with potential for the use of soda as
an alkali in the production process. Two furnaces have been identified, the
earlier example (1616-1618) is significant because of contemporary accounts
which document the failure of new technology using oil shale as a fuel, while
the later example (1618-1623) is well understood through excavation. The
structures of both furnaces remain in situ, along with the associated working
contexts, glass residues and related deposits and will provide scope for the
study of the development of glass manufacture and the reasons for its failure
at this site.
The salterns at Kimmeridge date from the Early Iron Age and continued into the
Romano-British period. The manufacturing technique was unusual, as salt was
produced by heating pans of seawater, probably using shale as a fuel from an
early stage. The salterns at Kimmeridge were also associated with pottery
manufacture (Black Burnished Ware), an association also reflected more widely
in south Dorset, north Kent and north Somerset, where the availability of
suitable clays and fuel satisfied the requirements of both industrial
processes.
The industries represented at Kimmeridge, therefore, form a unique association
providing considerable insight into industrial development over an extensive
period.
Details
The monument includes an alum works and other multi-period industrial remains
representing salt and glass production, some 20th century military remains
and an associated group of jetties and breakwaters, situated upon a natural
exposure of Bituminous shale along the coast at Kimmeridge. The industrial
activity fell into several distinct phases, although the proximity of the
various sites has produced a closely integrated group of archaeological
remains.
The earliest industrial activity identified at Kimmeridge is salt working. The
salterns (the complex of features used to extract salt from brine) date from
the Early Iron Age and Romano-British periods. The remains include burnt shale
deposits, a distinctive `briquetage' or remains produced by the extraction
process including vesicular slag, distinctive handmade bricks and the remains
of vessel containers. This material relates to the simplest form of artificial
salt extraction using heat. Similar salt working is also thought to have
occurred within the area during the 17th century.
Historical evidence indicates that an early, but unsuccessful attempt was made
to produce alum at Kimmeridge during the 1570s. Later, Sir William Clavell
established a successful works which operated from 1605, although it closed
following an alleged breach of monopoly in 1618. An inventory of 1617 records
the presence of two alum houses at Kimmeridge and the possible stone
foundations of these have been identified along the foreshore, buried beneath
the accumulated waste deposits of the later industries. During the alum
production period, shale was excavated on a large scale, creating quarries
visible behind the coastal cliffs. The natural course of the stream was
diverted to the north west, in order to avoid flooding and to allow the
natural course of the stream to be used for access. Archaeological survey and
partial excavation has recorded an extensive and well stratified sequence of
industrial deposits relating to the alum industry, including burnt shale, slag
and other deposits, all lying to the south of the shale quarries.
The glass works occupy the central northern area and partially overlie the
site of the alum works. Partial excavations in 1980-1981 identified two
furnaces dating from 1616-1618 and 1618-1623. Both structures remain preserved
in situ along with associated deposits. The later furnace occupied the centre
of a stone founded structure, 12m square in plan and served by a central flue.
The foreshore is known to support a sequence of timber and stone-built jetties
and breakwaters which date between at least the 17th and 19th centuries. These
were designed to enable the export of the industrial products by sea.
To the north east are a group of large concrete blocks aligned north west by
south east. These represent anti-tank defences often known as `dragon's
teeth'. These were designed to prevent vehicular access and relate to wider
defences of the period in 1939-1945.
All fence posts and gates relating to modern field boundaries and the boat-
houses and coastguard hut, and the surfaces of the track and carpark are
excluded from the scheduling, although the ground beneath these features is
included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
