Details

The monument includes the best surviving remains of the limestone quarrying,
mining and processing industry in Dudley. It includes the remains of the
quarries, mines and caverns, the lime kilns, the horseshoe kilns, the lime
pyes and part of the canal transport network at Wren's Nest, Mon's Hill,
Castle Hill and the Black Country Museum. Most of the remains are located
upon two parallel outcrops of Much Wenlock Limestone, deposited in the
Silurian Period, forming steep-sided ridges oriented approximately
north-south and standing north of Dudley town centre.

Lime has been mined here for centuries; the stone for the 11th century Dudley
Castle and 12th century St James Priory was obtained from quarries on Castle
Hill. From an early date most lime was, however, used in the production of
lime mortar and lime washes, and from the 17th century in agriculture to
improve soil conditions. These early uses involved surface quarries and
simple processing, including burning to produce quicklime by means of kilns
constructed close to the source of the lime. These kilns or `lime pyes' were
often temporary structures, dug into the ground and filled with layers of
limestone and charcoal. Once sealed and fired, they burned for a week until
quicklime was produced. They continued in use from the late medieval period
until the Industrial Revolution. The earliest record of a grant for lime
works on the Wren's Nest outcrop dates from 1634, and throughout the 17th
century references are made to lime works, including a 25 year farm on lime
works at the Old Park, taken out by John Darby father of Abraham Darby.

Following the discovery, in the 18th century, that limestone could be used as
a flux when smelting iron, demand increased and limestone quarries were
widely established. In 1725 Lord Dudley's bailiff estimated the value of the
Wren's Nest lime workings to be £250 per annum. John Snape's map of 1785
illustrates a quarry on Castle Hill. The Dudley Estate ran the quarries for
most of their history, leasing them out only for a short time during the
slump of the 1790s to early 1800s.

By 1796 Charles Norton was extracting 60,000 tonnes per annum from the Wren's
Nest and Castle Hill quarries, although surface limestone was exhausted the
miners began to excavate huge caverns, later given exotic names such as
Singing Cavern, Dark Cavern and Mud Hole Cavern.

As well as using steam winding engines to bring limestone up to the surface
via shafts, subterranean canals were built to provide the simplest means of
transport for extracted material. The first canal, known as `Lord Ward's
Arm', and constructed in 1776, linked works on the east side of Castle Hill
to the Birmingham Canal Navigation, with an underground terminus at Castle
Mill Basin. From here other canals were constructed. The Dudley Tunnel, which
linked the canal networks on both sides of the watershed was the second
longest canal tunnel in Britain. This network of subterranean canals joined
the caverns and scattered lime works and included several underground basins
and wharves. Plate railways were installed for wagons to carry limestone from
the quarry faces down to the basins and wharves. The hub of the system was
the huge Castle Mill Basin, which, in common with several other basins, later
had the roof removed to allow better access and lighting. A group of
horseshoe-shaped lime kilns was constructed at the entrance to the tunnels
outside the Tipton Portal.

By the mid-19th century the limestone in the underground workings beneath
Castle Hill was starting to run out, and is shown as a wooded area called
`the wilderness' on a map of 1839, with a number of leisure walks and
carriage drives running north-south along the ridge. Some of the abandoned
caverns were used as tourist features; Lord Dudley installed gas lighting in
Dark Cavern and used it for concerts, balls and lectures. Limestone working
continued at greater depth away from Castle Hill, most being transported to
Lord Dudley's lime works by the Tipton Portal. In 1842 a bank of massive,
continuous feed draw kilns, with their own canal basin, was erected behind
the horseshoe kilns. With the advent of the railway in the 1850s, a further
series of kilns was built at the East Castle Works, and sidings and a goods
station had been constructed there by the 1880s. Although the location of
these works is well documented, the level of archaeological survival at the
site is uncertain and at present the East Castle Works is not included in the
scheduling. Mining continued at Wren's Nest until 1924 and the Wren's Nest
lime works continued to work until 1935, with small amounts of limestone
being fired until the wartime blackout restrictions led to the closure of the
kilns in 1939.

Both the Castle Hill and Wren's Nest/Mon's Hill outcrops preserve evidence of
surface workings including numerous small pits representing smaller, earlier
quarries and crown holes, caused by collapses into later underground
workings. Later surface workings were characterised, on both outcrops, by
deep linear excavations, often in the form of steep-sided trenches running
along the sides of the hill, following the most accessible outcrops of
limestone. Other surface features include the line of the subterranean canal
at Mons Hill, visible as a series of breather shafts dug along its course. At
least four lime pyes have been located on the Wren's Nest/Mons Hill outcrop
and a further two on the Castle Hill outcrop. A pair of later draw kilns is
located on the western slope of Wren's Nest, constructed in 1902 of brick and
stone and surviving to a height of approximately 6m. Remains of four
horseshoe kilns surviving up to a height of approximately 2.5m are also
visible.

A second group of kilns stands at Tipton Portal. These include three
different types of kiln. A later 18th century draw kiln is situated on the
south side of the Portal, which retains its draw arch and internal details.
East of this, also on the south side of the canal, are the remains of three
early 19th century horseshoe or flare kilns. To the south of these stands a
bank of four massive mid-19th century draw kilns, accessed by a separate
canal arm with a large basin. These large draw kilns were originally
constructed in the 1840s as a set of three with vertical brick shafts
accessed by tunnels separating them. These tunnels may have been used for
transferring material from different levels. A fourth kiln was built on to
the east side of the bank and is apparently of a larger volume than the
others. A mineral railway provided access to the top of the bank from which
the kilns were loaded, and a loading crane was installed on the top of the
bank in 1910.

Although many of the subterranean caverns have been infilled, or their
entrances have been blocked for health and safety reasons, several of the
larger examples associated with the underground canal network survive. The
entrance to the Seven Sisters Cavern at Wren's Nest survives on the west of
the hillside, with huge columns of rock left intact to support the roof,
while on the Castle Hill outcrop, Singing Cavern and Stores Cavern survive.
The remains of shot holes drilled into the limestone, which filled with
gunpowder, stopped with clay then fired to break-up the limestone, can be
seen in the walls and roofs of some of the surviving caverns. In 1998
archaeological observation undertaken in Wren's Nest basin recorded at least
three layers of L-shaped plate rails on metal sleepers surviving beneath the
wharf area, with a single set of flanged wrought iron rails, dating from
modernisation in the 1830s, lying above them.

Within the subterranean canal network several wharves survive. These appear
to have been fronted by baulks of timber adjacent to brick-built retaining
walls. Chains and rails used to secure boats for tipping survive, as do
miners' walkways constructed of thick planks 12 inches wide supported by
metal spikes hammered into the walls with iron rings, possibly used for rope
handrails. Spikes in the roof of the Wren's Nest East Basin are believed to
have held a hanging bridge giving access to both sides of the basin.

A number of features are excluded from the scheduling: the small two-storey
brick cottage adjacent to the kilns, remains of the stone-built single-story
stable block, all modern paths, roads, surfaces, fences, walls, street, park
and garden furniture; all modern dwellings, buildings, the housing estates
centred on Priory Road, the college buildings on Wren's Nest and the animal
shelters and enclosures of Dudley Zoo; the modern sections of the Dudley
canal tunnel driven to provide boat trip access and the modern fixtures and
fittings associated with the boat trip, however, the ground beneath all these
features is included.

The ground beneath the housing estates centred on Priory Road is excluded
from the scheduling to a depth of 4m, although the subterranean remains of
the lime industry and canals further below are included.

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

Source: Historic England

Reasons for Scheduling

Limestone or chalk has been the basic ingredient for lime mortar from at
least Roman times. Since the medieval period, lime has also been used as
agricultural fertiliser and, since the early 19th century, widely used in
a variety of other industries: as a flux in blast furnaces, in the
production of gas and oil, and in the chemical, pharmaceutical and food
industries.
The lime industry is defined as the processes of preparing and producing
lime by burning and slaking. The basic raw material for producing lime is
limestone or chalk: when burnt at high temperature (roasted or calcined),
these rocks release carbon dioxide, leaving `quicklime' which, by chemical
reaction when mixed with water (`slaking'), can be turned into a stable
powder - lime. Lime burning sites varied in scale from individual small
lime kilns adjacent to a quarry, to large-scale works designed to operate
commercially for an extended market and often associated with long
distance water or rail transport. Lime burning as an industry displays
well-developed regional characteristics, borne out by the regional styles
of East Anglia, West Gloucestershire or Derbyshire.
The form of kilns used for lime burning evolved throughout the history of
the industry, from small intermittent clamp and flare kilns, to large
continuously fired draw kilns that could satisfy increased demand from
urban development, industrial growth and agricultural improvement.
Small-scale rural lime production continued in the later 19th and 20th
centuries, but this period of the industry is mainly characterised by
large-scale production and the transfer of technologies from the cement
and other industries. The demand for mortars grew steadily during the 19th
and 20th centuries. The successful production of mortars made with
artificial cement represented an economic challenge to lime production and
gradually replaced the use of lime mortars in major construction and
engineering projects.
From a highly selective sample made at national level, around 200 lime
industry sites have been defined as being of national importance. These
have been defined to represent the industry's chronological depth,
technological breadth and regional diversity.

The lime working remains in Dudley include a well-preserved limestone
quarrying landscape with evidence of both surface and underground working
with associated canals, lime kilns and other structures dating from the late
medieval period throughout the Industrial Revolution until the modern era.
Excavation has demonstrated the survival of several phases of features within
the caverns, including the survival of wood and iron implements, the fixtures
and fittings associated with railway and canal transportation, as well as
evidence of shot holes and tool marks preserved on the cavern faces. Together
these provide evidence for the history and technological development of lime
working from its earliest days until the modern period, demonstrating
developments in tools, extraction methods and transportation. Survival of
excellent documentary and cartographic sources combined with physical
archaeological remains illustrates the economic importance of the lime
industry in Dudley, including details of the working conditions endured by
the workforce over a considerable period of time.

Source: Historic England