Chalk Mines

Chalk Mines

Chalk is one of the most common rocks in Kent and Sussex but, to most people, the only known use has been where it was quarried to make cement. it has had other uses, however, for brick making, building and lime burning, and there were a number of quite extensive mines for this purpose. The dimensions of these mines were impressive, with passages up to 25ft high and a width of 15ft tapering to 6ft at the top. In cross-section they resembled a Norman arch and the practice of leaving solid pillars of chalk for support gave them the name of ‘pillar and stall’ mines. Since chalk is relatively soft, the passage ends were excavated by pick and shovel with the spoil being removed in baskets or wheelbarrows. Rather than excavate a 25ft high face, the technique was to drive a series of stepped ‘benches’ about 6ft high which allowed several men to work at the same time. The excavated chalk was thrown back onto the lower benches and so to the floor for collection. One departure from this method was to drive a face sloping at 45 degrees so that the chalk fell to the floor under its own weight. The chalk was stable enough to require no props but, if loose areas were encountered, the face was simply abandoned and carried on elsewhere. There was no problem from explosive gases and lighting was by candle or, at a later date, paraffin lamp.

Mines for Brickmaking

In the 19th century, Britain’s economic expansion led to the creation of suburban London and an unprecedented demand for the supply of building materials to the capital. Northwest Kent was admirably positioned to meet this demand and the Dover Road, the Medway and Thames Rivers and the expanding rail network provided an easy route for movement of materials. The area between Lewisham and Sittingbourne was subjected to massive opencast excavation of chalk for cement as well as clay for the yellow stock bricks that built most of Victorian London. A look at 19th century Ordnance Survey maps will show brickfields and clay pits in abundance and much of the area was lowered 6ft as the surface clay was stripped away.

There is no space to describe brick making operations in detail but several publications are included in the bibliography for those interested. The industry declined rapidly in the 1900s as clay deposits became depleted and cheaper bricks came on the market from around Fletton in Bedfordshire. Today there are only two working brickfields left and most of the others have been built upon. The yellow colour in the bricks came from adding about 15% chalk to the mixture and, although some brickfields had associated chalk quarries, many could not afford the space. The answer was to sink shafts on site and mine the chalk in situ. Some had inclined drift entrances to permit horse drawn trucks to enter the mine.

Plumstead Chalk Mines

These are situated under Alliance Road, Grasclene Road, Villacourt Road and Sutherland Road. Between 1937 and 1950 the major topic of discussion for the inhabitants of the houses in these roads was the instability of the ground, which collapsed frequently in the roads, gardens and under houses! In September 1937 a collapse occurred at Rockcliffe Gardens in a children’s playground, leaving a crater measuring 80ft x 60ft x 30ft deep. More collapses occurred in 1938 and Woolwich Borough Council employed consultants to carry out a series of bores to determine the extent of any cavities.

On 2nd June 1939, a party of Council workmen were filling in one of the boreholes. One of them, Samuel Gardner, was walking 10ft from the borehole when the ground suddenly subsided beneath him. At first, his head could be seen above the earth at the bottom of the crater but then the sides collapsed on him and he suffocated. The body was recovered from a depth of 30ft the following day. Collapses continued throughout the next decade but remedial action was prevented by the Second World War. The London County Council finally put through Parliament the LCC (Woolwich Subsidences) Act in 1950 and this empowered them to take whatever action was necessary to remedy the subsidences. Bores, headings and shafts were driven and surveys made, revealing the presence of a massive chalkmine. This was gradually filled by floating in pulverised fuel ash and, following this expensive operation, the ground stabilised.

The mines dated from the 19th century and were working up to 1920, being recorded by HM Inspector of Mines as South Metropolitan Mine, Gregory’s Mine, King’s Highway Mine and Cemetery Mine. They have also had other names at various times and may well be linked underground. We can get an idea of conditions from a report dated 1903:

‘…Following the descent of the shaft on a hand-cranked winch … a lofty gallery runs through the dead white chalk to a working face 300-400 yards away, where the miners are busy with picks and shovels. Down the centre of the main galleries are two rows of flat metals on which run the small trolleys used to convey the chalk from the working face to the shaft. The mine manager himself superintends the driving of all new headings, shapes the roof and trims the corners; the workmen do the rough cutting after the roof has been secured. Throughout the mine the same bed of hard chalk forms a remarkably flat roof.’ Another report in 1906 says:

‘…The brickyards, four in number, obtain chalk by shafts 120ft, 80ft and 150ft deep; the South Metropolitan Mine is entered by a sloping tunnel. Below Gregory’s Brickyard, the aggregate length of the galleries is stated to be at least two miles. The tunnels are, as a rule, 9ft wide at floor level, diminishing to 3ft at the roof, and 25ft high; but these proportions are modified according to the harder or softer nature of the chalk, the presence of joints, etc. The mine was opened about 50 years ago.’ A further report in 1909 says:

‘…the party, including the owner of the mine, became hopelessly lost while exploring the more remote disused galleries. Our guide was a man who had worked in the mine most of his life but we wandered in vain for over an hour, till reduced to our last candle, when, by a lucky mischance, one of the party, owing to the darkness, fell a distance of about 6ft. Happily he escaped without injury and discovered that he was in the newer workings and was able to direct us until an easier way out was found.’

Crayford Chalk Mines

These were similar in extent and old Ordnance Survey maps show a string of workings for clay and chalk between Erith and Crayford in the Slade Green area. The area was investigated by the archaeologist F.Q. Spurrell at the turn of the century whilst looking for flint mines:

‘…All of these caves formed part of a series … and one has been worked for chalk up to within the last 50 years, presenting a very interesting labyrinth of modern galleries, which have united several old shafts once separate. The great chalk pit was once a denehole in my recollection. The modern workings are for brickmaking purposes.’

The pit, is now filled and overgrown. It was some 150ft in diameter and 49ft deep to the west of Maiden Lane. The 1862 Ordnance Survey map shows a rail track entering the pit and running up to what might have been a mine entrance. There was also an air shaft shown.

Dartford Chalk Mine

This is off Shepherds Lane and the associated brickfield was owned by C.N. Kidd, who had several local businesses including a brewery. The brickfield itself is believed to date from 1886 and finally ceased just before the First World War. The older brickfield and the mine were to the north of the road and clay was excavated from an open pit to a depth of 13ft. This was connected to a smaller pit on the south side via a tunnel running under the road. Building development stopped expansion of the northern pit by 1890 and, although operations were transferred to the other one, it was decided to continue with the mine rather than sink a new one. Graffiti in the mine indicates that it ceased in 1911. The mine workings were underneath the eastern part of the pit and it was here that the crushing, etc. plant was situated. The washbacks (settling ponds) were wisely situated further away in view of the danger of leaks which could have flooded the mine. Perhaps this was a lesson learnt from the Cemetery Mine at Plumstead where such a leak caused a disastrous collapse.

There was a well near the mineshaft and, around 1920, a surface drain was diverted into it, a short tunnel being driven to connect it with the mine workings that acted as a soakaway. The original shaft was capped over about this time but it is not known why the drain wasn’t diverted into this to save all the extra work! The area was used as a tip, mainly by Kidd’s brewery for disposal of clinker and broken bottles, and the site of the shaft was lost under the fill.

The mine was re-entered in 1980 by members of Kent Underground Research Group, who used a wire ladder to gain access via the well. The workings were in good condition and there had been little change since the mine had ceased working. The ‘tide marks’ on the walls, however, showed that the drain had sometimes flooded the mine to a height of 5ft. There was a natural fissure in the floor which drained the water away but it obviously could not cope with sudden inflows. The galleries were on average 9ft wide at the base, tapering to 1ft 6in at roof level which was 20-30ft high.

The method of working in this mine was quite unusual. Instead of excavating the chalk in a series of benches up to 5ft high, here the benches were only a few inches high and less than 3ft deep. As the chalk from the face above fell down onto the floor, the benches broke up to leave a steep, slippery slope. This must have meant an awkward climb up to the face and difficult working conditions. A mine of this size rarely employed more than 2-3 men underground and it is likely that wheelbarrows were used to take the chalk to the shaft. Near the shaft is an interesting feature where a small room has been cut out with a flight of 4 steps up to it. This was probably a place where tools were stored and men had their meal breaks.

The shaft bottom was always a busy place in a mine and there are several deep rope grooves in the chalk where heavy loads were hauled up. A number of ‘tally boards’ were also cut into the walls to count the number of loads being taken out of a particular part of the mine. There are interesting graffiti here cut into the walls such as ‘COME UNTO ME ALL THAT LABOUR’, ‘GOD IS LOVE’ and the owner’s name ‘C.N. KIDD DARTFORD’. At one point in the mine, a miner’s progress along a pilot side gallery can be traced from patches of soot on the roof. As he advanced the face 3ft or so, he moved his candle to a new position and there is a row of these patches leading back towards the main gallery. The candleholder was actually found still in place at the last position.

At some of the faces, miners had either carved their name on the walls or smoked it on the roof with a candle. Most of these were dated between 1901 -1911 and a later one, ‘A.E.J. Price 28.11.31’, was probably a council official inspecting the drain. Even the mine engineman, R. Fulker, had found time to go down and leave his name carved for posterity. In 1988 the site was taken over to build houses and work was carried out to rock bolt and concrete some parts of the mine roof for stability. A ladder was installed in the well shaft and a manhole at the surface is situated in one of the access roads. Access is strictly controlled.

Frindsbury Chalk Mine

This was sited underneath Bill Street and there was a shaft on either side of the road. It was commenced in the 19th century by the West family, who ran a large building and brickmaking business in the Medway Towns. Official figures give an annual output of around 400 tons of chalk and it is believed to have ceased around the late 1920s. Like many of this type of mine, it was operated on a shoestring budget and a traction engine pumped out the well and wound in the shaft using flat belts in the latter part of its life. There are no visible remains today, since the whole area has been built upon, but a number of subsidences have occurred. The history has already been published in some detail (see bibliography).

Mines for Building Material

Chalk is not a good building stone since it is very susceptible to erosion. It can, however, be used in house footings or road foundations since it is not so exposed to the atmosphere. Since the cost of purchasing and transporting chalk from nearby quarries could be prohibitive, there were occasions when it was mined in situ.

Bostall Estate Chalk Mine

In 1899 the Royal Arsenal Co-operative Society embarked on an ambitious project – the building of an entire housing estate from scratch. The site chosen was at Abbey Wood where they held land that had been used for market gardening. The RACS Works Dept moved from Woolwich to set up operations on the site with workshops and a light tramway to move materials around the area. To utilise local resources, a mine was excavated to provide chalk for the road foundations and lime for the internal plasterwork. Although it is generally referred to by the above name, it has also been known in the past as Suffolk Place Mine.

The 8ft diameter shaft was sunk in January 1900 to a depth of 6Oft and headings were driven out to develop the mine. The floor was at the water table but this had been planned on purpose so that mortar could be mixed at surface with water pumped from the mine. The hardworked engine which operated the pumps also drove the winding hoist in the shaft as well as machinery in the workshops via a system of shaft drives. By use of a dynamo it produced electric power and this mine was unique in being lit completely by electric light. The galleries average 10ft wide x 18ft high and the traditional method of benches was used to extract the chalk. The mine only had a short life and was abandoned in 1906, the building phase above ending eventually in 1914 after 1,052 houses had been built.

During the First World War, the mine was adapted as an air raid shelter and an inclined tunnel was driven down from surface. This subsequently suffered roof fails and, despite local protests, it was not reused again in 1939. It was next re-entered in 1967 by members of Kent Underground Research Group when an updated survey was carried out. The shaft was then resealed and access is restricted. The only thing remaining of the site today is the old works canteen which is now used by the council social services department.

Mines for Limeburning

The process of limeburning was carried out in kilns where chalk was burnt to produce quicklime (commonly called lime). When water was added to this, it became slaked lime which could be used for various purposes. As a fertiliser, it was much more efficient than spreading chalk alone since it could be absorbed into the soil straight away. In the building industry it was used to make plaster and, by adding sand produced mortar. There were many small limekilns in Kent and Sussex and these were supplied from open pits or sometimes a denehole. When large quantities were required, however, it was not always practicable to excavate a quarry and sometimes associated chalk mines were excavated.

Chislehurst Chalk Mine

One of the largest of such mines was at Chislehurst and it is now open to the public as Chislehurst Caves. The chalk was first excavated and probably dates from medieval times. A document of that time refers to the ‘Marlera at the Swellinde Pette in the Villa of Chislehurst’ which has been translated as a marl pit in a hollow for burning chalk. A 17th century map refers to the woodland above the mine as Well Wood and this possibly refers to a denehole-type shaft for supplying chalk to the kilns.

The mine itself consists of three separate sets of galleries known as the Inner, Middle and Outer Series. The Outer Series was dug horizontally into the hill from the original chalk pit and is possibly the oldest of all, being less stable than the others and having suffered several roof fails in the past. it is the smallest mine and ceased operations before the aalleries penetrated very far, probably around 1800.

The Inner Series was driven from a separate chalk pit to the South and an extensive set of galleries was worked.from the Fast of the pit which contained the limekilns. In 1840 five kilns were being supplied fromthese workings but severe flooding caused weakening of the galleries between 1855 and 1860 and several roof fails occurred.

The Middle Series dates from the same time, or perhaps slightly later, but was worked from an 85ft shaft further up the hill. The workings extended in all directions except to the South West because the mine manager knew of the proximity of the other two mines and of the property boundary at surface. Chalk was brought out of the shaft and either burnt at adjacent kilns or used in brickmaking. The will of James Taggart dated 1834 states: ‘…including the brickfields containing seven acres more or less and my freehold wood called Susan Wood, with lime kilns, brick kilns and chalk pit’ (the word ‘pit’ in those days referred to a shaft).

Taggart left the business to his brother-in-law George Bascombe who continued to produce ‘bricks, pots, lime and chalk’ and intended to extend the mine workings further under the common to the North East. For this purpose, another shaft was sunk to avoid transporting the chalk a long way underground. Unlike the other two mines (which were driven horizontally and could use horse transport), wheelbarrows had to be used to transport the chalk to the shaft bottom. The ruts in the floor caused by these wheelbarrows were noted during an investigation of the workings in 1904. Despite the plans, the area around the second shaft was not fully developed and mining ceased around 1866. This was mainly due to the invention of the steam shovel because this machine could quickly remove large quantities of overburden. Large quarries were developed at Swanscombe, Northfleet and Gravesend that could produce chalk very cheaply. With the introduction of water transport and better roads, the local mines found it impossible to compete.

At some time prior to abandonment, two tunnels were driven to connect up with both the Outer and Inner Series which had already ceased. It seems likely that Bascombe wanted to check on the exact position of the other mines with a view to mining any unworked areas. Since Bascombe was a keen gardener, he adapted part of the Middle Series to grow celery and other vegetables and sunk a well in the mine to obtain water for the plants. A spiral passage was excavated into this section from his property on the surface and this is now known as ‘Cavaliers Passage’. Bascombe was also a keen amateur archaeologist and it is perhaps significant that he did not consider any of the chalk workings to be ancient or mysterious.

In 1885, when mining had long since ceased, a great controversy arose as to the origins of the great chalk caverns. Almost as much correspondence was generated as in the argument about deneholes! At the turn of the century the owner of the Bickley Arms Hotel began to clear out parts of the mine and installed ‘electric glowlamps’. He allowed members of the public to explore the mine and there was a visit in 1903 by a party of ‘scientific men’, including a Mr Nichols who was the Vice-President of the British Archaeological Association (the same organisation that Bascombe had belonged to!). Nichols published his opinions and concluded that the three sets of tunnels belonged to different periods, viz. Roman, Saxon and Druid. He dated Bascombe’s well to the Roman period, called the stepped benches Druids’ altars and interpreted the two haulage shafts as ancient deneholes of Celtic origin!

A further visit to the mine in 1904 included two mining engineers called T.E. and R.H. Forster. They stated that the caves were simply three chalk mines whose main excavations had been made in the 17th-18th centuries. From then on, everyone joined in the argument with correspondence in the newspapers and heated debates at meetings. The advocates of the Druids theory’ shouted down the chalk mine theorists and vice versa.

In the First World War the mines were used by the Government to store explosives and a light tramway was installed. It is said that the picric acid from the explosives turned the chalk yellow in some places. The wooden hut which is now the office dates from this time. In 1920 the present owner acquired the site and attempted to grow mushrooms. During the Second World War the mines became the largest air raid shelter in the Greater London area with up to 8,000 people using it in 1940 at 1d per night. A new ventilation shaft was sunk together with powerful fans to keep the airflow circulating. New tunnels were driven to the surface to act as exits and a great deal of brickwork installed for toilets, washrooms, canteens and a first aid post. It was the wartime nurses, in fact, who drew the plan of the mines on the wall in the ‘map room’, through which visitors pass today.

Since the war, the mines have been open to the public as a show cave and the guides seem to have adopted Mr Nichols’ version of the history as being more entertaining. Visitors are now shown Romans digging out chalk, Druids’ sacrificial altars, a witch’s cave and many other delights, including a ghost or two! Modern researchers, however, are convinced that the Victorian mining engineers were nearer the truth and that the main development of the mines took place in the late 18th to early 19th centuries. There were also similar chalk mines in the vicinity at logs Hill and Camden Park.

Eastry Chalk Mine

A lime burning business was carried on by the Foord family at Eastry from 1811 -1914 and a chalk mine was developed on several levels. The workings resemble a three-dimensional maze and demonstrate the effect of mining without any forward planning. Access was originally by shaft but an inclined tunnel was later driven to the surface to emerge by the limekiln. The mine was abandoned following pressure from villagers who were worried that their houses were being undermined. It was subsequently turned into a folly and village festivities were held underground. It was the practice during these events to nail patterns of branches to the wall and the old nails still remain to puzzle visitors.

During the Second World War the long gallery was used by the Home Guard as a rifle range and the workings were later opened to the public as a show cave for a short time. It was during this period that two elaborate paintings resembling stained glass windows were placed on the walls. The mine is now on private property and access is strictly controlled but the owners have preserved the workings.

Kent Underground Research Group