Reasons for Designation
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. 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 early sites are known on the
south coast, particularly in Dorset and Hampshire.
Alum works comprise two main monument types: the quarry where extraction and
initial processing took place, and the alum house where final processing took
place. Alum shale was extracted from quarries sited on steep inland hillsides
or coastal cliffs. Initial processing on the quarry floor consisted of
calcination 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 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 offers important 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.
The alum works at Ash Holm still survive and significant remains of the
technological processes are preserved. As an early and relatively short lived
inland alum works, important evidence of early processes will be preserved,
together with evidence for cement stone exploitation. The importance of the
monument is enhanced by the considerable amount of documentary evidence which
survives. The early date of the site and the fact that it was short-lived is
particularly noteworthy. Few comparable sites survive and consequently this
example preserves significant information on the technology of the early alum
industry.
Details
The monument includes the remains of the alum quarries and associated features
in the south face of East Row Beck valley in Mulgrave Woods, 350m south east
of Mulgrave Castle. As well as the quarries, the monument also includes
structures used for the initial processing and transportation of the alum.
The Ash Holm works was established by 1609 and was one of the first group of
alum works opened in the area. The works closed in the 1730s, partly because
the inland location and falling prices made the works unprofitable and also
because Mulgrave Woods was being landscaped as a formal park.
The quarry includes a massive scoop cut into the south face of the river
valley. At the south face there is a near vertical quarry face above a series
of terraces which represent the working platforms for extracting the alum
shale. Below the face is a steep scarp slope partly obscuring the terraces
with large stone and boulders strewn around. To the east and west sides of the
scoop the sides slope to the central quarry floor. At the base of the quarry
face, extending northward, is a confused series of spoil tips. These tips are
of both quarry waste and spent shale, discarded after the process known as
steeping. There are a number of waterlogged ponds adjacent to the tips which
are interpreted as the remains of steeping pits which produced a liquid known
as alum liqour, one of the initial processes. Further north on lower ground
are more spoil tips and earthworks from features associated with the later
stages of processing. The alum works utilised the natural slope of the land in
order to have easy movement of alum liquor from one process to another. There
is a clearly defined tramway extending northward from the area of processing
works. Further remains of structures such as the alum house where final
processing took place as well as workshops, a laboratory, offices and stores
are thought to survive below ground level.
The site was also exploited for cement stone mining, using calcereous nodules
mined from the alum shales. The mining for cement stone has partly obscured
the remains of the alum works. The production of cement may also have stopped
when the Mulgrave Woods was formally emparked in the 18th century.
The footbridge is excluded from the scheduling, although the ground beneath it
is included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
