Mines of Paris
Encyclopedia
The Mines of Paris comprise a number of abandoned, subterranean mines
under Paris
, France
, connected together by galleries. Three main networks exist; the largest, called the grand réseau sud ("large south network"), lies under the Ve, VIe, XIVe and XVe arrondissements
, a second under the XIIIe arrondissement, and a third under the XVIe, though other minor networks are found under the XIIe, XIVe and XVIe for instance. Together, the mines and galleries run for approximately 280 kilometers.
Exploring the mines is prohibited by the prefecture
and penalised with heavy fines. A limited part of the network (1.7 km) has been used as an underground ossuary
, known as the catacombs of Paris
. The catacombs were temporarily closed between September and 19 December 2009, after which they could be legally visited again from the entrance on Place Denfert-Rochereau. The entire subterranian network is commonly but mistakenly referred to as "the catacombs". Despite restrictions, Paris' former mines are frequently toured by urban explorer
s popularly called cataphile
s.
, a geological bowl-like shape created by millennia of sea immersion and erosion. Much of north-western France spent much of its geological history as a submerged sea water coastline, but towards our era, and the formation of our continents as we know them today, the then relatively flat area that would become the Paris region became increasingly elevated, alternately invaded and sculpted by both sea water, inland sea water "lagoons" and fresh water, in addition to above-water air and river erosion. This cycle resulted a rich and varied geological strata containing many minerals that would become a source of growth and wealth for the Paris region.
The Paris area was a relatively flat sea-bottom In the early Cretaceous
period: first in a deep-sea environment, then under a more agitated near-shoreline sea towards the end of the same period, Paris' largely silicium-based sedimentary deposits became, under the action of pressure and the carbonic acid
content of seawater, a thick deposit of clay
. The invasion of calcium-rich seas then covered this with an even more important layer of chalk
. Paris emerged from the sea towards the end of the Cretaceous
, and Palaeozoic-era continental shifts, particularly the Variscan orogeny
geological upheavals, created a series of hills and valleys throughout the Parisian basin, creating conditions ideal to the mineral deposits that would appear over the next eras.
After a long period above sea level that ended towards the Cenezoic era, Paris began a period of alternation between sea and land environments. Paris was the middle of a shoreline of bays and "lagoons" of still seawater, an environment perfect for the silica-based sea life abundant then. As sea creatures died and settled to the lagoon bottom, their shells would mix with the deposits already present; pressure from additional sea-life sedimentation and the chemical action of the water would transform the result into a sedimentary stone quite particular to the Paris area, "calcaire grossier" (calcaire lutécien in more modern publications). Paris' most important deposits of this stone occurred during the Eocene
epoch's Lutetian
age; in fact, the age itself is named for the sedimentary activity in the Paris era, as Lutèce
was the city's name in Roman times.
Paris' next important mineral deposit came with the Bartonian
age. After a period of land-sea altercation that brought layers of sand and low-quality calcaire grossier, the sea regressed again to return only occasionally to re-fill lagoons with seawater. The result was stagnating pools evaporating seawater: the salts of these, mixed with other organic matter and mineral deposits, crystallised into the calcium sulphate composition that is gypsum
. This evaporation cycle occurred several times over this age, creating several layers of gypsum divided by layers of mineral left by the sea's brief return. In all, Paris' gypsum deposits are divided into four "masses", with the last appearing, the "haute masse", being the most important and most exploited in Parisian history. Gypsum, an "evaporite" mineral, is known for its fragility against freshwater invasion.
The sea returned one last time to the Parisian basin towards the end of the Paleogene
period, leaving several layers of varied sediment capped with a thick layer of clay
. The latter deposit was important for Paris' gypsum deposits when the Paris basin rose, this time definitely, from the sea in the early Neogene
, as they would protect them from erosion from air and the elements.
and Belleville
are the only places where gypsum remained, as the ancestor to today's Seine
once ran as wide, almost along its present path, as half the city, with many arms and tributaries.
, Marne
and Bièvre
rivers exposed many levels of Paris' underlying stratification to open air. Minerals available from the surface, beginning with Paris' highest elevations in the valleys created by this erosion are: the plaster
deposits in the upper reaches of the Right Bank hills of Montmartre
and Belleville
; lower in the valleys are sand
and limestone deposits nearest the surface on Paris' Left Bank. The underlying Clay
strata was accessible from the surface in the lowest points of the river valleys, that is to say in the lowest points of the Seine
, Marne
and Bièvre
valleys.
hill.
Gypsum mines, the origin of the famous Plaster of Paris, used this technique with an added third dimension: as some of northern Paris' gypsum deposits measured 14 meters in some places, miners would create their tunnel grids in the top of the deposit, then begin extracting downwards. A gypsum mine in a particularly thick deposit had almost a cathedral air upon depletion because of the towering columns and arches of mineral remaining. Only one example of this sort of gypsum-mining remains in Paris today, in a renovated "grotto" under the Buttes-Chaumont gardens.
This method of burrowing was effective in the short-term, but over time the solid mineral, subject to the elements and the earth's shifting, could erode or fissure, endangering the solidity of the mine.
The majority of Paris' stone deposits were in its Left Bank, and at the time of the city populace's 10th-century move to the Right Bank, were well to the suburbs of the former Roman
/Merovingian city. As the stone from the abandoned ruins became depleted from the 13th century, new mines began to open further from the city centre. Earlier mines closer to the city centre, when discovered, sometimes served a purpose: when Louis XI donated the former Chateau Vauvert, a property which today forms the northern part of the Luxembourg Gardens, to the Chartreuse order in 1259, the monks renovated the caverns under their property into wine cellars, and continued the exploitation of stone to the ancient mine's extremities.
By the early 16th century, there were stone excavations operating around today's Jardin des Plantes, Boulevard St-Marcel, Val-de-Grâce hospital, southern Luxembourg (by then the Chartreuse Coventry) and in areas around the rue Vaugirard. Paris' then suburban plaster mines remained for the most part to the Right Bank Montmartre and Belleville
hills.
It was only with its expansion past its 13th-century walls that the city began to build on previously-mined land which eventually led to mining disasters. The left bank faubourgs or suburbs were the most at risk: in the 15th century, the largest were the faubourg Saint-Victor (from the eastern extremity of the rue des Écoles and south down the rue Geoffroy St Hilaire); the faubourg St Marcel (rue Descartes, rue Mouffetard) and the faubourg Saint-Jacques (along today’s rue Saint-Jacques below the rue Soufflot); lastly, the faubourg (then bourg) Saint-Germain-des-Prés below today’s church of the same name.
Although seventeenth-century Right Bank Paris had in five centuries expanded past three successive arcs of fortifications, Left Bank Paris was nowhere near as dense in comparison within its unchanged but crumbling 13th-century city walls. Many royal and ecclesiastical institutions came to the area during this period, but it seems that the mined state of the Paris faubourg underground had been forgotten by then: The Val de Grâce coventry and the Observatoire
observatory, built from 1645 and 1672 respectively, were found to be undermined by immense caverns left by long-abandoned stone mines; reinforcing these took most of the budget reserved for both projects.
Growth of the faubourgs continued along the main routes from the city, but began to expand at a faster rate with the rise of traffic along the routes to the Fontainebleau and Versailles castles. The route de Fontainebleau (extending to the south of today's Place Denfert-Rochereau
), then called Rue d'Enfer and now called Avenue Denfert-Rochereau, would be the site of one of Paris' first major mine collapses in 1774, when about 100 feet of the street collapsed to a depth of about a hundred feet.
's decision to create a special division of architects responsible for the inspection, maintenance, and repair of the ground under royal buildings within and around Paris. Another division of inspectors created around the same time, but under the direction of the Ministry of Finance, claimed the role of assuring the safety of the national roadways that were their jurisdiction. Created officially on the 24th of April 1777, the Inspection Générale des Carrières entered service on the same eve after a new collapse of the route de Fontainebleau (Avenue Denfert-Rochereau) outside of the barrière d'Enfer city gateway. Although the Ministry of Finance continued to claim jurisdiction over damaged roadways, this rather inept service was eventually succeeded by the Crown-appointed IGC.
As the centuries of mining under Paris' underground were mostly uncharted and thus largely forgotten, the real extent of former mines was unknown then. All important buildings and roadways were inspected, any signs of shifting were noted, and the ground underneath was sounded for cavities. Roadways were particularly problematic; instead of sounding the ground around the route, inspectors instead tunneled directly under the length of endangered roadway, filling any cavities they found along the way, and reinforcing the walls of their tunnels with solid masonry to eliminate the possibility of any future excavations and disasters. When a length of roadway was consolidated, the date of the work was engraved in the tunnel wall under it, next to the name of the roadway above; Paris' underground tunnel renovations, dating to as early as 1777, are today still a living testimony to Paris' old street names and roadways.
During the 18th century, the growing population
of Paris resulted in the saturation of existing cemeteries, raising public health
concerns. Towards the end of the 18th century, it was decided to create three new large cemeteries and to condemn the existing cemeteries within the city limits. Remains were progressively moved to a renovated section of the abandoned mines that would eventually become a full-fledged ossuary
. The entrance is located on present day Place Denfert-Rochereau.
The ossuary became a tourist attraction on a small scale from the early 19th century and has been open to the public on a regular basis from 1867. Although it is officially called the Ossuaire Municipal, it is widely known as "the catacombs". Though the entire subterranean network of Paris' mines is not a burial place as such, the term 'Catacombs' is commonly used to refer to the whole.
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
under Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, connected together by galleries. Three main networks exist; the largest, called the grand réseau sud ("large south network"), lies under the Ve, VIe, XIVe and XVe arrondissements
Arrondissements of Paris
The city of Paris is divided into twenty arrondissements municipaux administrative districts, more simply referred to as arrondissements . These are not to be confused with departmental arrondissements, which subdivide the 101 French départements...
, a second under the XIIIe arrondissement, and a third under the XVIe, though other minor networks are found under the XIIe, XIVe and XVIe for instance. Together, the mines and galleries run for approximately 280 kilometers.
Exploring the mines is prohibited by the prefecture
Prefecture of Police
The Prefecture of Police , headed by the Prefect of Police , is an agency of the Government of France which provides the police force for the city of Paris and the surrounding three suburban départements of Hauts-de-Seine, Seine-Saint-Denis, and Val-de-Marne...
and penalised with heavy fines. A limited part of the network (1.7 km) has been used as an underground ossuary
Ossuary
An ossuary is a chest, building, well, or site made to serve as the final resting place of human skeletal remains. They are frequently used where burial space is scarce. A body is first buried in a temporary grave, then after some years the skeletal remains are removed and placed in an ossuary...
, known as the catacombs of Paris
Catacombs of Paris
The Catacombs of Paris or Catacombes de Paris are an underground ossuary in Paris, France. Located south of the former city gate , the ossuary holds the remains of about 6 million people and fills a renovated section of caverns and tunnels that are the remains of Paris' stone mines...
. The catacombs were temporarily closed between September and 19 December 2009, after which they could be legally visited again from the entrance on Place Denfert-Rochereau. The entire subterranian network is commonly but mistakenly referred to as "the catacombs". Despite restrictions, Paris' former mines are frequently toured by urban explorer
Urban Explorer
Urban Explorer is a 2011 horror-thriller film directed by Andy Fetscher.-Premise:Four young urban explorers from the USA, South America, Asia and Europe meet up in Berlin via the internet to explore the subterranean relics of Nazi Germany...
s popularly called cataphile
Cataphile
Cataphiles are urban explorers who illegally tour the Paris "catacombs", the term popularly used to describe a series of underground tunnels that were formerly a network of stone mines.-Unauthorized visits:Entrance to the catacombs is restricted...
s.
Paris' sedimentary minerals
Paris lies within the Paris BasinParis Basin (geology)
The Paris Basin is one of the major geological regions of France having developed since the Triassic on a basement formed by the Variscan orogeny.-Extent:...
, a geological bowl-like shape created by millennia of sea immersion and erosion. Much of north-western France spent much of its geological history as a submerged sea water coastline, but towards our era, and the formation of our continents as we know them today, the then relatively flat area that would become the Paris region became increasingly elevated, alternately invaded and sculpted by both sea water, inland sea water "lagoons" and fresh water, in addition to above-water air and river erosion. This cycle resulted a rich and varied geological strata containing many minerals that would become a source of growth and wealth for the Paris region.
Formation
Paris has spent most of its geologic history under water, which is why it has such varied and important accumulations of sedimentary minerals.The Paris area was a relatively flat sea-bottom In the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period: first in a deep-sea environment, then under a more agitated near-shoreline sea towards the end of the same period, Paris' largely silicium-based sedimentary deposits became, under the action of pressure and the carbonic acid
Carbonic acid
Carbonic acid is the inorganic compound with the formula H2CO3 . It is also a name sometimes given to solutions of carbon dioxide in water, because such solutions contain small amounts of H2CO3. Carbonic acid forms two kinds of salts, the carbonates and the bicarbonates...
content of seawater, a thick deposit of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
. The invasion of calcium-rich seas then covered this with an even more important layer of chalk
Chalk
Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
. Paris emerged from the sea towards the end of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
, and Palaeozoic-era continental shifts, particularly the Variscan orogeny
Variscan orogeny
The Variscan orogeny is a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica and Gondwana to form the supercontinent of Pangaea.-Naming:...
geological upheavals, created a series of hills and valleys throughout the Parisian basin, creating conditions ideal to the mineral deposits that would appear over the next eras.
After a long period above sea level that ended towards the Cenezoic era, Paris began a period of alternation between sea and land environments. Paris was the middle of a shoreline of bays and "lagoons" of still seawater, an environment perfect for the silica-based sea life abundant then. As sea creatures died and settled to the lagoon bottom, their shells would mix with the deposits already present; pressure from additional sea-life sedimentation and the chemical action of the water would transform the result into a sedimentary stone quite particular to the Paris area, "calcaire grossier" (calcaire lutécien in more modern publications). Paris' most important deposits of this stone occurred during the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
epoch's Lutetian
Lutetian
The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between and . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Middle Eocene subepoch...
age; in fact, the age itself is named for the sedimentary activity in the Paris era, as Lutèce
Lutetia
Lutetia was a town in pre-Roman and Roman Gaul. The Gallo-Roman city was a forerunner of the re-established Merovingian town that is the ancestor of present-day Paris...
was the city's name in Roman times.
Paris' next important mineral deposit came with the Bartonian
Bartonian
The Bartonian is, in the ICS's geological timescale, a stage or age in the middle Eocene epoch or series. The Bartonian age spans the time between and . It is preceded by the Lutetian and is followed by the Priabonian age.-Stratigraphic definition:...
age. After a period of land-sea altercation that brought layers of sand and low-quality calcaire grossier, the sea regressed again to return only occasionally to re-fill lagoons with seawater. The result was stagnating pools evaporating seawater: the salts of these, mixed with other organic matter and mineral deposits, crystallised into the calcium sulphate composition that is gypsum
Gypsum
Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...
. This evaporation cycle occurred several times over this age, creating several layers of gypsum divided by layers of mineral left by the sea's brief return. In all, Paris' gypsum deposits are divided into four "masses", with the last appearing, the "haute masse", being the most important and most exploited in Parisian history. Gypsum, an "evaporite" mineral, is known for its fragility against freshwater invasion.
The sea returned one last time to the Parisian basin towards the end of the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
period, leaving several layers of varied sediment capped with a thick layer of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
. The latter deposit was important for Paris' gypsum deposits when the Paris basin rose, this time definitely, from the sea in the early Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...
, as they would protect them from erosion from air and the elements.
Erosion
This is when Paris began to take the form we know today: huge rivers resulting from the melting of successive ice ages cut through millions of years of sediment, leaving only formations too high or too resistant to river erosion. Paris' hills of MontmartreMontmartre
Montmartre is a hill which is 130 metres high, giving its name to the surrounding district, in the north of Paris in the 18th arrondissement, a part of the Right Bank. Montmartre is primarily known for the white-domed Basilica of the Sacré Cœur on its summit and as a nightclub district...
and Belleville
Belleville
-Places in North America:Canada*Belleville, Nova Scotia*Belleville, OntarioUnited States of America*Belleville, Arkansas*Belleville, California*Belleville, Illinois, the largest US city named Belleville**Belleville -Places in North America:Canada*Belleville, Nova Scotia*Belleville, OntarioUnited...
are the only places where gypsum remained, as the ancestor to today's Seine
Seine
The Seine is a -long river and an important commercial waterway within the Paris Basin in the north of France. It rises at Saint-Seine near Dijon in northeastern France in the Langres plateau, flowing through Paris and into the English Channel at Le Havre . It is navigable by ocean-going vessels...
once ran as wide, almost along its present path, as half the city, with many arms and tributaries.
Open-air quarries
The most primitive mining technique was to extract a mineral where it could be seen on the surface: many millennia of erosion by the ancestors of the Paris basin's SeineSeine
The Seine is a -long river and an important commercial waterway within the Paris Basin in the north of France. It rises at Saint-Seine near Dijon in northeastern France in the Langres plateau, flowing through Paris and into the English Channel at Le Havre . It is navigable by ocean-going vessels...
, Marne
Marne
Marne is a department in north-eastern France named after the river Marne which flows through the department. The prefecture of Marne is Châlons-en-Champagne...
and Bièvre
Bièvre
Bièvre is a Walloon municipality located in the Belgian province of Namur. On 1 January 2006 the municipality had 3,151 inhabitants. The total area is 109.59 km², giving a population density of 29 inhabitants per km².-External links:*...
rivers exposed many levels of Paris' underlying stratification to open air. Minerals available from the surface, beginning with Paris' highest elevations in the valleys created by this erosion are: the plaster
Plaster
Plaster is a building material used for coating walls and ceilings. Plaster starts as a dry powder similar to mortar or cement and like those materials it is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after setting,...
deposits in the upper reaches of the Right Bank hills of Montmartre
Montmartre
Montmartre is a hill which is 130 metres high, giving its name to the surrounding district, in the north of Paris in the 18th arrondissement, a part of the Right Bank. Montmartre is primarily known for the white-domed Basilica of the Sacré Cœur on its summit and as a nightclub district...
and Belleville
Belleville, Paris
Belleville is a neighbourhood of Paris, France, parts of which lie in four different arrondissements. The major portion of Belleville straddles the borderline between the 20th arrondissement and the 19th along its main street, the Rue de Belleville...
; lower in the valleys are sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
and limestone deposits nearest the surface on Paris' Left Bank. The underlying Clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
strata was accessible from the surface in the lowest points of the river valleys, that is to say in the lowest points of the Seine
Seine
The Seine is a -long river and an important commercial waterway within the Paris Basin in the north of France. It rises at Saint-Seine near Dijon in northeastern France in the Langres plateau, flowing through Paris and into the English Channel at Le Havre . It is navigable by ocean-going vessels...
, Marne
Marne
Marne is a department in north-eastern France named after the river Marne which flows through the department. The prefecture of Marne is Châlons-en-Champagne...
and Bièvre
Bièvre
Bièvre is a Walloon municipality located in the Belgian province of Namur. On 1 January 2006 the municipality had 3,151 inhabitants. The total area is 109.59 km², giving a population density of 29 inhabitants per km².-External links:*...
valleys.
Underground mining
Open-air quarrying became quite difficult and even costly when the desired mineral lay too deep below the surface, as sometimes enormous amounts of earth and other unwanted deposits would have to be removed before it could be extracted. One means of avoiding this problem was to dig horizontally into a hillside along the mineral strata from where it was visible in its flank, but the Paris area had few mineral deposits, save gypsum, whose disposition fulfilled these conditions. There were few open-air stone quarries by the 15th century; instead, miners would access the targeted stone deposit through vertical wells, and dig into it horizontally from there. Although it seems that well-mining method only appeared then, there is evidence that Romans used this technique to mine clay under Paris' Left Bank Montagne Sainte-GenevièveMontagne Sainte-Geneviève
The Montagne Sainte-Geneviève is a hill on the left Bank of the Seine in the 5th arrondissement of Paris.On the top of the Montagne, one can visit the Panthéon or the Bibliothèque Sainte-Geneviève, which is often full of students from La Sorbonne and other nearby universities...
hill.
Piliers tournés
No matter the means they used to access the underground mineral, miners had to provide a means of maintaining the enormous weight of the ceiling over their horizontally-burrowed excavations. The earliest means to this end, in a technique called piliers tournés, became common from the late 10th century: a tunnel would be dug horizontally along the deposit; tunnels bisecting the first were opened along the way, and tunnels parallel to the initial tunnel would be opened through these. The result was a grid of columns of untouched mineral deposit, or "piliers tournés", that prevented a mine's collapse. In areas where a mineral was removed in a wider swath than the rest of the mine, usually towards the edge of the exploitation, miners would complement the natural stone columns with piliers à bras, or stacks of stone creating a supporting column between floor and ceiling.Gypsum mines, the origin of the famous Plaster of Paris, used this technique with an added third dimension: as some of northern Paris' gypsum deposits measured 14 meters in some places, miners would create their tunnel grids in the top of the deposit, then begin extracting downwards. A gypsum mine in a particularly thick deposit had almost a cathedral air upon depletion because of the towering columns and arches of mineral remaining. Only one example of this sort of gypsum-mining remains in Paris today, in a renovated "grotto" under the Buttes-Chaumont gardens.
This method of burrowing was effective in the short-term, but over time the solid mineral, subject to the elements and the earth's shifting, could erode or fissure, endangering the solidity of the mine.
Hagues et Bourrages
Another technique appearing towards the early 18th century, hagues et bourrages, was both more economically and structurally sound. Instead of tunnelling into the exploitable mineral, miners would begin at a central point and extract stone progressively outwards; when they had mined to a point that left a wide area of the ceiling unsupported, they would erect a line of piliers à bras, continue their extraction beyond that line, then return to build a second parallel line of stone columns. The space along both lines of columns were then transformed into walls with stone blocks, or hagues, and the space between filled with packed rubble and other mineral detritus (or bourrage). This technique allowed much more of the targeted mineral to be extracted, and provided a support that could both settle and shift with the mine ceiling it supported.Growth over abandoned mines
There is no concrete proof of any mining activity before the late thirteenth century. The earliest known text is a brief mention in the town commerce register: Paris had 18 "quarriers" in 1292. The first written act concerning any mine dates from almost a century later, 1373, in an authorisation that a certain Dame Perrenelle be permitted to operate the plaster mine already existing in her property to the lower flank of Montmartre.The majority of Paris' stone deposits were in its Left Bank, and at the time of the city populace's 10th-century move to the Right Bank, were well to the suburbs of the former Roman
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....
/Merovingian city. As the stone from the abandoned ruins became depleted from the 13th century, new mines began to open further from the city centre. Earlier mines closer to the city centre, when discovered, sometimes served a purpose: when Louis XI donated the former Chateau Vauvert, a property which today forms the northern part of the Luxembourg Gardens, to the Chartreuse order in 1259, the monks renovated the caverns under their property into wine cellars, and continued the exploitation of stone to the ancient mine's extremities.
By the early 16th century, there were stone excavations operating around today's Jardin des Plantes, Boulevard St-Marcel, Val-de-Grâce hospital, southern Luxembourg (by then the Chartreuse Coventry) and in areas around the rue Vaugirard. Paris' then suburban plaster mines remained for the most part to the Right Bank Montmartre and Belleville
Belleville
-Places in North America:Canada*Belleville, Nova Scotia*Belleville, OntarioUnited States of America*Belleville, Arkansas*Belleville, California*Belleville, Illinois, the largest US city named Belleville**Belleville -Places in North America:Canada*Belleville, Nova Scotia*Belleville, OntarioUnited...
hills.
It was only with its expansion past its 13th-century walls that the city began to build on previously-mined land which eventually led to mining disasters. The left bank faubourgs or suburbs were the most at risk: in the 15th century, the largest were the faubourg Saint-Victor (from the eastern extremity of the rue des Écoles and south down the rue Geoffroy St Hilaire); the faubourg St Marcel (rue Descartes, rue Mouffetard) and the faubourg Saint-Jacques (along today’s rue Saint-Jacques below the rue Soufflot); lastly, the faubourg (then bourg) Saint-Germain-des-Prés below today’s church of the same name.
Although seventeenth-century Right Bank Paris had in five centuries expanded past three successive arcs of fortifications, Left Bank Paris was nowhere near as dense in comparison within its unchanged but crumbling 13th-century city walls. Many royal and ecclesiastical institutions came to the area during this period, but it seems that the mined state of the Paris faubourg underground had been forgotten by then: The Val de Grâce coventry and the Observatoire
Paris Observatory
The Paris Observatory is the foremost astronomical observatory of France, and one of the largest astronomical centres in the world...
observatory, built from 1645 and 1672 respectively, were found to be undermined by immense caverns left by long-abandoned stone mines; reinforcing these took most of the budget reserved for both projects.
Growth of the faubourgs continued along the main routes from the city, but began to expand at a faster rate with the rise of traffic along the routes to the Fontainebleau and Versailles castles. The route de Fontainebleau (extending to the south of today's Place Denfert-Rochereau
Place Denfert-Rochereau
Place Denfert-Rochereau, previously known as Place d'Enfer, is a public square located in the 14th arrondissement of Paris, France, in the Montparnasse district, at the intersection of the boulevards Raspail, Arago, and Saint-Jacques, and the avenues René Coty, Général Leclerc, and , as well as the...
), then called Rue d'Enfer and now called Avenue Denfert-Rochereau, would be the site of one of Paris' first major mine collapses in 1774, when about 100 feet of the street collapsed to a depth of about a hundred feet.
The consolidation period
The above disaster was in part responsible for the Conseil du RoiConseil du Roi
The Conseil du Roi or King's Council is a general term for the administrative and governmental apparatus around the king of France during the Ancien Régime designed to prepare his decisions and give him advice...
's decision to create a special division of architects responsible for the inspection, maintenance, and repair of the ground under royal buildings within and around Paris. Another division of inspectors created around the same time, but under the direction of the Ministry of Finance, claimed the role of assuring the safety of the national roadways that were their jurisdiction. Created officially on the 24th of April 1777, the Inspection Générale des Carrières entered service on the same eve after a new collapse of the route de Fontainebleau (Avenue Denfert-Rochereau) outside of the barrière d'Enfer city gateway. Although the Ministry of Finance continued to claim jurisdiction over damaged roadways, this rather inept service was eventually succeeded by the Crown-appointed IGC.
As the centuries of mining under Paris' underground were mostly uncharted and thus largely forgotten, the real extent of former mines was unknown then. All important buildings and roadways were inspected, any signs of shifting were noted, and the ground underneath was sounded for cavities. Roadways were particularly problematic; instead of sounding the ground around the route, inspectors instead tunneled directly under the length of endangered roadway, filling any cavities they found along the way, and reinforcing the walls of their tunnels with solid masonry to eliminate the possibility of any future excavations and disasters. When a length of roadway was consolidated, the date of the work was engraved in the tunnel wall under it, next to the name of the roadway above; Paris' underground tunnel renovations, dating to as early as 1777, are today still a living testimony to Paris' old street names and roadways.
Ossuary
Population growth
Population growth is the change in a population over time, and can be quantified as the change in the number of individuals of any species in a population using "per unit time" for measurement....
of Paris resulted in the saturation of existing cemeteries, raising public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
concerns. Towards the end of the 18th century, it was decided to create three new large cemeteries and to condemn the existing cemeteries within the city limits. Remains were progressively moved to a renovated section of the abandoned mines that would eventually become a full-fledged ossuary
Ossuary
An ossuary is a chest, building, well, or site made to serve as the final resting place of human skeletal remains. They are frequently used where burial space is scarce. A body is first buried in a temporary grave, then after some years the skeletal remains are removed and placed in an ossuary...
. The entrance is located on present day Place Denfert-Rochereau.
The ossuary became a tourist attraction on a small scale from the early 19th century and has been open to the public on a regular basis from 1867. Although it is officially called the Ossuaire Municipal, it is widely known as "the catacombs". Though the entire subterranean network of Paris' mines is not a burial place as such, the term 'Catacombs' is commonly used to refer to the whole.