archaeological survey june 2013

CORRANTREE LEAD MINE

ARCHAEOLOGICAL SURVEY

JUNE 2013

Report by

John Pickin

for

Forestry Commission

Scotland

Archaeological survey: Corrantree lead mine

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ARCHAEOLOGICAL SURVEY

JUNE 2013

Contents

Introduction: 2

History: 2

Site description and condition: 4

Historic maps: 15

Extent of site: 17

Health and Safety: 17

Management: 17

References: 18

Appendix 1 – list of photographs: 18

Report prepared for Forestry Commission Scotland

by

John Pickin

High Weirston House, Leswalt, Stranraer, Dumfries and Galloway DG9 0RQ

Email: [email protected] Tel: 01776 870270


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NGR: NM 8000 6590

Parish: Ardnamurchan

Area: Lochaber

Region: Highland

NMR: NM86NW4

HER: MHG 133

Scheduled monument: 5513

Survey photographs: CR 1- 24 (see Appendix 1 for details)

Introduction

In May 2013 Forestry Commission Scotland commissioned a survey of the Ccorrantree lead mine.

The aim of the survey was to locate and describe the principal archaeological features and provide

information on their condition and any associated health and safety issues. The survey was carried

out in June 2013.

The Corrantree lead mine, which is a Scheduled Ancient Monument, was worked intensively from

1722 to 1815 and reworked in the mid-nineteenth century; the site was examined in the 1950s but

no development took place. Features survive from all these periods and include opencasts, levels

and shafts, dressing floors, spoil tips, a mine office and associated building, a wheel pit and crushing

mill and a self-acting incline tramway.

All archaeological features were photographed and given a ten-figure grid reference and measured

sketches were also made of selected features.

A Monument Management Plan for the site was produced by Forestry Commission Scotland in 2009

and runs from 2011 to 2016.

History

Corrantree lead mine is the most westerly of the Strontian mines. The Strontian mines were

discovered in 1722 and worked as an integrated group by the proprietor of the estate, Sir Alexander

Murray of Stanhope. In 1729 the lease for the mines was given to the Duke of Norfolk and Company

who erected a four-hearth smelting mill at Strontian village. A few years later the lease was taken

up by the York Buildings Company who worked the mines continuously until 1815. Between 1817

and 1836 the mines were worked on a small scale by the owner and then leased again to a number

of companies with the final phase of operation being between 1850 and 1872. In 1901 a proposal


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Plan of Corrantree lead mine. The numbers relate to the principal archaeological features recorded

during the survey.


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was made to reopen the mines but work was confined to the Bellsgrove mine and no development

took place at Corrantree (Wilson 1921: 83).

The mine was resampled but not developed in the 1950s (Flett 1959: 108). In 1968 the Scottish

Canadian Company carried out a programme of drilling at Corrantree to establish the extent and

type of the remaining mineral deposits but no mining was undertaken (Kimbell 1986: 3). During the

1980s some of the other mines at Strontian were reopened for barite but the Corrnatree mine was

not part of this development.

Description and condition

The Corrantree mine worked a lead vein which outcrops at the surface between NM 8006 6560 and

NM 8048 6585. Mining consisted of a series of shallow opencast excavations (1, 9-11 below) and the

more westerly opencasts (9-11) were drained by a level (13) driven from the north bank of the Allt

Tarsuin. The opencast workings and their associated hand-dressing floors for ore treatment (2, 3, 6-

8) probably relate to the first phase of operation between 1722 and 1815. The manager’s house and

office (16) are likely to date to the same period but may have continued in use until the mine closed

in the 1870s.

A 122m long level (17), known as Deep Level, was driven beneath the opencast workings to explore

the vein at depth (Wilson 1921: 86). Ore from Deep Level was taken to a rope-operated incline (21-

22) and delivered to a water-powered crushing mill (23) at the bottom of the hill; given the large size

of the wheel pit, this phase of mining is probably 19th century and is liekely to belong to the 1850-

1872 period. The only evidence for 20th century working is the collapsed wooden shed or bothy with

broken drill cores (15) which probably was in use during the 1950s or 1968 drilling programme.

The individual features at the mine are described below:

1. Opencast mine working, NM 80408 65843 – 80478 65849 (Photos CR 1.1-7)

The mineral vein has been worked as an opencast vein for a distance of approximately 75m. The

dimensions of the opencast vary but average 6m deep and 3m wide. At NM 80438 65843 there is a

4m high rise; there is a good exposure of the mineral vein at this point.

Condition: fair.

2. Spoil tip and dressing floor, NM 80436 65 822 (Photos CR 2.1-5)

On the hill slope above and immediately S of opencast 1 is a level area of mine spoil, 20m x 22m. It

comprises two areas of finely broken quartz with a central section of broken unmineralised rock. In

the N part of the spoil heap is a low stone structure defining a space 2.5m x 3m; this is probably a

bench for the manual crushing (hand-dressing) of lead ore.

Condition: fair. Some erosion of tip material.


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Sketch plan of dressing floor 2.

3. Mine level NM 80358 65840 (Photos CR 3.1-2)

Level, 1.6 m wide x 1.3m high, in a rock outcrop on N side of burn and partly concealed by mine

spoil. Immediately E of the level are some shallow rock- cut surface excavations on a quartz vein.

Condition; good. In competent rock. Entrance covered with modern grill.

4. Ore crushing bench, NM 80354 65828 (Photos CR 4.1-2)

A flat topped stone-built structure, approx. 2m x 2m, constructed against the natural slope on the S

side of the burn. Surrounded by finely crushed quartz. Probably a bench for the manual crushing

(hand-dressing) of lead ore.

Condition: fair.

5. Mine shaft, NM 80335 65839. (Photos CR 5)

A rectangular rock-cut shaft, 1.4m x 2.3m, in-filled with mine spoil on the N side. Flooded.

Condition: fair. Risk of infill from spoil tip above.

6. Mine level and dressing floor, NM 80 285 65863. (Photos CR 6.1-2)


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Entrance to small mine level, 0.50m x 0.70m, excavated on an exposed mineral vein. Some 6m SW is

a flat-topped stone-built structure, 2m x 4m, constructed against the S bank of a gully; probably a

bench for the manual crushing (hand-dressing) of lead ore. On the opposite side of the gully is a 5m

length of dry stone retaining wall.

Condition: fair. Structures appear stable.

Sketch plan of mine level and dressing floor 6.

7. Building (possible), NM 80252 868. (Photos CR 7.1-2)

A series of discontinuous lengths of coursed stone define the foundations of an L-shaped structure,

6m x 12m, possibly a building or small enclosure. The ground inside and around the structure is

uneven, perhaps from shallow surface mining.

Condition: poor. Structures reduced to foundation course in places. Covered with vegetation

(mainly heather).

8. Ore crushing bench, NM 80253 80877. (Photos CR 8)

A flat-topped stone-built platform, 3m x 5m, constructed against the natural slope with a coursed

face on the S side. Probably a bench for the manual crushing (hand-dressing) of lead ore.

Condition: fair. Stable structure, no threat.


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Opencast 1, view east. Opencast 1, mineral vein exposure

at NM 40438 65843.

Dressing floor 2, view west. Level 3 with vein working to right, view north east.

Hand-dressing bench 5, view south east . Shaft 6.


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Level 6, view east . Dressing bench and retaining walls in front of level 6.

Ore dressing bench 8, view north. Opencast working 9, view east.

Opencast working 10, view east. Opencast working 11, view east.

.


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9. Opencast working, NM 80221 65880. (Photos CR 9.1-2)

An opencast mine working, 2.5m x 8m, excavated on the ore vein and known as Allen Cameron’s

Sump (Wilson 1921, Fig. 13). The vein itself is exposed on the E face of the excavation and the

working is flooded. To the SW of the opencast is a short length of dry stone walling built against the

bank. E of the opencast a shallow rock-sided gully, 50m long, marks the line of the mineral vein and

may be a prospecting trench

Condition: fair. Rock appears stable. Fenced.

10. Opencast working, NM 80198 65888. (Photo CR 10)

A flooded opencast mine working, 3m x 10m, with a linear spoil tip on the S side. Known as Windlass

Stope (Wilson 1921, Fig. 13).


11. Opencast working, NM 80165 65899. (Photo CR 11)

Large opencast mine working, approximately 2m wide and 30m long, with a sloping entrance at the

W end. On the s side is a low, linear spoil tip and to the W is a narrow, low spoil tip, 4m x 15m, with a

partial revetment wall.


12. Structure (?) and spoil tip, NM 80133 65905. (Photo CR 12)

An area of crushed spoil, 3m x 6m, with a short length of stone walling to the E. Thick heather

obscures the full extent of this feature.

Condition; poor. Partly covered with vegetation.

13. Mine level, NM 80120 65859. (Photo CR 13)

A rock-cut mine level, 1.10 m wide x 0.50m wide, on the N bank of the Allt Tarsuinn. Entrance

covered with a modern metal grill.

Condition: good. In competent rock. Metal grill across entrance.

14 Building, NM 80079 65855. (Photo CR 14)

On the S bank of the Allt Tarsuinn and downstream of level 13 are the degraded stone foundations

of a rectangular building, 3m x 8m. The NE corner of the structure has an angled buttress, probably

to prevent flood damage from the adjacent stream. The structure is partly covered with corrugated

iron sheets, presumably collapsed roofing material.

Condition: poor. Risk of flood damage


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15 Building, NM 80056 65878. (Photos CR 15.1-3)

The collapsed remains of a timber-framed wooden shed built on a level terrace, 7m x 12m. Within

the structure are two iron bed frames and to the SE, in an annexe defined by three large floor

timbers, are a considerable number of broken drill cores. An earlier roofed building is shown at this

location on the First Edition edition OS map.

Condition: poor. The structure has collapsed.

16 Buildings, NM 800028 65914

Two adjacent buildings, probably the mine’s offices, stores and lodgings.

Building A is rectangular, 5.40m x 13.60m with a gable at the W end standing to 3.60m; it is divided

into two units. The larger unit is in the W section and has a central door and two side windows in

the S wall and central fireplaces in the gable and dividing walls. The smaller unit has a fireplace

against the dividing wall and a single opening or entrance in the S wall. The E end of the building is

constructed against the natural slope and is surrounded by a stone faced channel with a buttress

close to the NE corner on the N wall.

Building B is rectangular, 5.20m x 9.60m, and located SW of Building A. It is divided into two units of

similar size with openings in the S and E walls and a blocked doorway in the internal wall. There is a

fireplace against the W wall of the W unit.

Both buildings are shown as roofed structures on the First Edition OS map; the map also depicts a

rectangular enclosure is depicted on the N side of Building B.

Condition: good. Fallen rubble has been cleared from the around Building 16a and the wall heads are

clear of vegetation. The E room in Building 16b has also been cleared but the W room is partly

obscured with collapsed masonry; the wall heads are vegetation free. Saplings and heather have

been removed from within the fence enclosing the two buildings.

Sketch plan of Buildings 16a and 16b


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Level 13, view north. Building 14, view east.

Building 15, view north west. Buildings 16, view west.

Level 17 (Deep Level), view east. Spoil tip 20 and incline wheel structure 21, view

east.


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17. Mine level, NM 80058 65964

At the E end of a 20m long linear cutting is the entrance to a rock-cut mine level, 1.20m high x 1.40m

wide. There are some stretches of dry stone retaining wall along the sides of the trench.

Condition: good. The level has been driven in competent rock and is gated with a modern metal

grill.

18. Building (?), NM 80043 65973

At the NW end of the trench leading to mine level 17 are the stone foundations of a possible

structure, 2.50m x 2.50m, built against the natural slope and open on the S side.

Condition: poor. Reduced to foundation course.

19. Drain(?), NM 80035 65974.

W of the cutting leading to mine level 17 is a linear gully, 5m long, with slight stone banks along

either side which join at the W end. To the E the gully may continue upslope.

Condition: poor. The possible continuation to the E is masked with vegetation.

20. Spoil tip, NM 80031 65979

A large flat topped spoil tip, 9m x 24m, associated with mine level 17.

Condition: fair.

Sketch plan showing entrance to level 17, spoilt tip 20 and the top of the incline (21, 22).


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21. Inclined plane wheel house, NM 80018 65985

Constructed against the W end of spoil tip 21 are the remains of a stone-built structure associated

with the top of a self-acting inclined plane tramway (22). A sloping section of coursed stone,

probably the base for a hopper or an ore chute, is a set above a timer-braced rectangular recess,

2.40m x 5.40m, which contains a cast iron pulley wheel, 2.06m diameter, set horizontally on the

floor. The pulley wheel appears to be in situ. Directly in front of the wheel house is a level area, 4m

x 7m, with retaining walls to the N, S and W; in the centre is a low stone wall aligned on the central

axis of the inclined plane.

Condition: fair. The masonry retaining walls appear stable but the horizontal timber brace above the

pulley chamber is decayed.

22. Inclined plane, NM 80016 65992 – NM 79874 66050

The inclined plane survives as a linear earthwork which runs downslope between the wheel house

(21) and the water wheel pit (22). For most of its length it is an angled embankment, 4m wide, with

a central axial bank but in the lower section it forms a linear gully. It terminates at the W end in a flat

topped mound which is connected to the NE corner of the wheel pit by raised tramway bank.

Condition: poor. The earthwork appears intact and stable but is masked by thick vegetation (mainly

heather).

Sketch plan showing the western end of the incline (22), the water wheel and crusher (23) and spoil

tip 24.


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View down incline 22 with pulley in foreground. View up incline 22.

Water wheel structure 23– launder pillar . Water wheel structure 23, view west. Bank from

incline base at bottom right.

Water wheel structure 23, view north east Spoil tip 24.

with the crusher platform to the right.


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23. Wheel pit, NM 79822 66040

A massive rectangular, stone-built structure, 15m x 4.50m x 3.75m high. Built against the natural

slope, its N, S and W faces are free-standing. A raised embankment connects the NE corner of the

wheel pit with the mound at the base of the incline. A recess in the central section of the S wall head

corresponds to the wheel’s axel. A terraced platform against the S wall , 3.25m x 7m, marks the

position of the crushing mill. Close to the W end of the wheel pit are a number of cast iron fittings

from the crusher including cogs and rollers.

At the E end of the wheel pit are three free standing stone pillars, 2.50m x 0.80m x 1.60m high (only

the W pillar survives intact); these pillars supported a wooden launder or trough taking water to the

wheel. The downslope end of the wheel lade is at NM 79865 66037.

Condition: poor. The condition of this structure was highlighted in the recent Monument

Management Plan and it is still an area of concern. As described in the MMP the W end of the wheel

pit has collapsed, the inner core of the two side walls is exposed and the roots of a rowan tree

growing within the interior wheel pit threatens the stability of the whole structure. Collapsed

masonry partly obscures the crusher base on the S side. There is thick ground cover within the

fenced area surrounding the wheel pit and this obscures the three launder pillars and the line of the

lade.

24. Spoil tip, NM 79797 66062

A large flat-topped spoil tip, 11m x 35m, W of the wheel pit. The tip, which is crossed by a burn in its

s section, is composed of finely crushed waste derived from the crushing mill.

Condition: poor. A stream cuts through the S section of the tip and is causing erosion.

Historic maps

OS First Edition six-inch. Argyllshire, Sheet XVII, survey date: 1872

The First Edition OS six-inch map shows the layout of the mine in 1872 just before final closure. It

depicts the entrance to Deep Level (17), the mine office and associated building 16a and 16b (the

latter with a garden(?) enclosure), a roofed building on Allt Tarsuinn (15), the line of the incline (22)

with a square structure at its base and the crushing mill and wheel pit (23). The map also shows a

reservoir and ‘sluice’ south east of the eastern opencast and two more reservoirs, ‘sluices’ and a

lade system associated with the water supply for the crushing mill; these features are now masked

by heather or within forestry plantations.


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OS First Edition six-inch 1872.

OS Revised six-inch. Argyll and Bute sheet XVII.SE, revised 1897.

The Second or Revised edition, surveyed in 1897, marks the mine as disused and shows three roofed

structures (buildings 15, 16a and 16b), the wheel pit (23) and the entrance gully for Deep Level (17).

Mine plan and section 1871

Wilson (1921: Fig.13) includes a simplified plan and section of the mine in 1871. In addition to

surface features like ‘old water wheel’ and ‘old office’ it shows the extent of the underground mine

including the ‘stoped areas’ which are the actual workings on the mineral vein. The ‘shallow adit’

shown on the north bank of the Allt Tarsuin west of the top opencast was not located during the

present survey. It is apparent from the section that the mine was comparatively shallow.

A mine abandonment plan dated 1871 is held by the British Geological Survey (ref.: SP 1050) and is

likely to be the source of Wilson’s plan and section.


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Plan and section of the mine (Wilson 1921: Fig. 13)

Extent of site

The area of the existing Scheduled Ancient monument includes all the key features with the

exception of the eastern end of opencast 1 and dressing floor 2. Extending the SE corner of the SAM

to NM 80451 65830 would incorporate all the known industrial features.

Health and safety

All the deep opencast workings and the mine levels are securely fenced and gated and the standing

structures (buildings 16 and the wheel pit) are within securely fenced enclosures. The poor

structural condition of the wheel pit poses a potential risk but the fence reduces this to an

acceptable level.

Management recommendations

With the exception of the wheel pit and buildings 14 and 15 most of the archaeological features are

in a fair condition and under no direct threat; these features should be monitored on a regular basis.

No evidence was seen during the present survey of disturbance to the tips by mineral collectors – as

noted in the MMP report – but the tips should be monitored to establish the degree of future

disturbance from this activity.

Much of the site is covered with thick heather which masks some known features and may be

concealing others. The previously unrecorded hand- dressing floors and shallow surface works (6-

10) in the E section of the site are in an area of particularly thick ground cover and more detailed

field survey here would aid interpretation and possibly lead to the recognition of new features.


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Thick heather and mature plantations in the W section of the site conceal the systems of lades which

are shown on the First Edition OS map taking water to the wheel pit; this area would also benefit

form more detailed survey and interpretation. The lade system should be relocated and assessed

during future clearance work.

Building 14 is at risk from flood damage but the masonry buttress at the E end may be providing

adequate protection. The site should be monitored, ideally during flood conditions. If necessary a

realignment of boulders in the stream could provide an adequate barrier or diversion.

Building 15 has collapsed and the timber cladding and framework are at risk of decay. A

photographic survey would provide an adequate record.

The large rowan tree in the wheel pit appears to have been pruned or cut – as recommended in the

FCS MMP – but it is still alive and the roots continue to threaten the stability of the structure. If

possible the tree should be poisoned. Scrubby undergrowth within the wheel pit enclosure fence

should also be removed. Given the poor condition of the wheel pit it might be appropriate to

undertake a detailed measured survey in advance of further deterioration.

References

Flett, W. R. 1959. Problems Affecting the Exploitation of minerals in Scotland. In The future of non-

Ferrous mining in Britain and Ireland, 101-111. London: Institute of Mining and Metallurgy.

Kimbell, G. S. 1986. Geophysical surveys near Strontian. British Geological Survey: mineral

reconnaissance programme, report no.6. Keyworth.

Wilson, G. V. 1921. The Lead, Zinc, Copper and Nickel Ores of Scotland. Special Report on the Mineral

Resources of Great Britain, Vol. XVII. HMSO: Edinburgh.

APPENDIX 1

List of photographs (on disc).

Photo number Feature Description

CR 1.1 1 W end of opencast 1, view E.

CR 1.2 1 Detail of vein.

CR 1.3 1 Detail of vein.

CR 1.4 1 Detail of vein showing galena cubes in barite.

CR 1.5 1 Central section of opencast 1.

CR 1.6 1 View E to w end of opencast 1.

CR 1.7 1 View E to e end of opencast 1.


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CR 2.1 2 Ore-dressing bench, view E.

CR 2.2 2 Ore-dressing bench, view N.

CR 2.3 2 Tip 2, view W

CR 2.4 2 Tip 2, view W

CR 2.5 2 Detail of ore-dressing bench, view S.

CR 3.1 3 Level and vein working, view NE.

CR 3.2 3 Detail of level entrance.

CR 4.1 4 Ore-dressing bench, view S.

CR 4.2 4 Detail of ore-dressing bench.

CR 5 5 View of shaft top.

CR 6.1 6 Level entrance with vein exposure above.

CR 6.2 6 Ore-dressing bench.

CR 6.3 6 View E showing level, dressing bench and revetment walls.

CR 7.1 7 Wall footings, view W.

CR 7.2 7 Length of isolated coursed walling, view E. Built over shallow excavation?

CR 8 8 Ore-dressing bench, view N.

CR 9.1 9 Opencast, view E.

CR 9.2 9 Shallow vein workings e of opencast 9.

CR 10 10 Opencast, view E.

CR 11 11 Opencast, view E.

CR 12 12 View W of wall and spoil tip.

CR 13 13 Level entrance, view N.

CR 14.1 14 General view of building.

CR 14.2 14 General view showing buttress atEe end.

CR 15.1 15 General view W.

CR 15.2 15 General view NW.

CR 15.3 15 Detail of drill cores.

CR 16.1 16 General view SW.

CR 16.2 16 16a, W gable fireplace

CR 16.3 16 16b, view W.

CR 16.4 16 16a, S face.

CR 16.5 16 16a, S face.

CR 16.6 16 16a, S face.


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CR 16.7 16 16a, S face.

CR 16.8 16 16a E fireplace.

CR 16.9 16 16a E fireplace.

CR 16.10 16 16a W gable.

CR 16.11 16 16b, fireplace.

CR 16.12 16 16a, E gable.

CR 17 17 Level entrance, view E.

CR 18 18 General view N.

CR 19.1 19 General view E.

CR 19.2 19 General view S.

CR 19.3 19 General view W.

CR 20 20 View E across tip with level 17 in background.

CR 21.1 21 Wheel house, view E.

CR 21.2 21 View W down incline 22, pulley wheel in foreground.

CR 21.3 21 Wheel house, detailed view E.

CR 21.4 21 Wheel house, view NW.

CR 21.5 21 Detail of pulley wheel.

CR 21.6 21 Detail of pulley wheel.

CR 21.7 21 Top face of wheel house, view E.

CR 21.8 21 Wheel house, view E.

CR 21.9 21 Structure above hopper.

Cr 21.10 21 Pulley wheel, vertical view.

CR 22.1 22 View W down incline.

CR 22.2 22 View E up incline showing sunken section.

CR 23.1 23 View W with launder pillar and tramway bank.

CR 23.2 23 View of S face of wheel pit and crusher platform.

CR 23.3 23 Detail of cast iron crusher gearing.

CR 23.4 23 Detail of launder pillar, view E.

CR 23.5 23 Wheel pit wall head, view W.

CR 23.6 23 S face of wheel pit showing housing for water wheel axel.

CR 23.7 23 Crusher platform, view E.

CR 23.8 23 Detail of counter-weight from crusher.

CR 23.9 23 Cast iron crusher fittings.

CR 23.10 23 View E inside pit showing rowan tree.

CR 23.11 23 N and w faces of wheel pit.

CR 23.12 23 View E showing collapse of W wall.

CR 24.1 24 View SE.

CR 24.2 24 View e across tip.

archaeological survey june 2013

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