Alum works, other multi-period industrial remains and an associated group of jetties and breakwaters, Kimmeridge Bay


Heritage Category:
Scheduled Monument
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Date first listed:


Ordnance survey map of Alum works, other multi-period industrial remains and an associated group of jetties and breakwaters, Kimmeridge Bay
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The building or site itself may lie within the boundary of more than one authority.

Purbeck (District Authority)
National Grid Reference:
SY 90886 78790

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.


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.


The contents of this record have been generated from a legacy data system.

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Books and journals
Cox, P, Archaeological Recording in Kimmeridge Bay, (1996)
Cox, P, Archaeological Recording in Kimmeridge Bay, (1996)
Cox, P, Archaeological Recording in Kimmeridge Bay, (1996)
Crossley, D W, 'Arch Journal' in Excavation of a 17th Century Glasshouse at Kimmeridge, 1980, , Vol. 144, (1987), 340-384
Farrar, R A H, 'Salt - The Study of an Ancient Industry' in Prehistoric And Roman Saltworks In Dorset, (1975)
Field survey,


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 Digital, Culture, Media and Sport.

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