This is not a page about a place, but it is one about the funniest accident we know of, which is based on karst geology.
During the 19th and the beginning of the 20th century a drink called absinthe was very famous in France. It was produced at the Pernod Fils factory from 1805 until 1938. Like all those anise liquors (e.g. Ouzo, Raki,...) it is a clear liquid until it is mixed with water, then it becomes milky.
Absinthe was quite similar to today's Pernod, which contains star anise, fennel, coriander, mint and 12 other herbs. But the original version, absinthe, included also the flowers and leaves of grand wormwood (Artemisia absinthium) making it bitter. It was actually named absinthe after this ingredient, but was also called la fée verte ("the green fairy") because of the green colour. Wormwood was rumoured of being poisonous, destroying the brain, making impotent, and being an aphrodisiac. The poisonous touch was part of the Absinth myth and was probably one of the reasons why it was popular. Unfortunately those peculiarities where also the base of public accusations and a campaign by social conservatives and prohibitionists. They chose this drink partly due to its association with bohemian culture, which they despised, the whole campaign was political and not based on facts. The chemical compound thujone, which is present in the spirit in trace amounts, was blamed for being a dangerously addictive psychoactive drug and hallucinogen. It would have been hard to get a lethal dose, or even hallucinations, without being killed by the alcohol much earlier, but the discussion was not based on facts. This was the era of prohibition and grumpy killjoys were the order of the day, not objectivity.
As a result absinthe was outlawed in France and subsequently in many other countries of the world until 1915. The Pernod liqueur of today was created as a replacement in 1938, avoiding all the "unhealthy" stuff, which fortunately did not include anise and alcohol. A revival of absinthe began in the 1990s, following the adoption of modern European Union food and beverage laws that removed long-standing barriers to its production and sale. A reformulated absinthe based on the original recipe was released by Pernod in 2005. But back to the story, it happened almost 15 years before absinthe was outlawed.
On 11-AUG-1901 a lightning hit the plant of the Pernod company in Pontarlier. It was set on fire, and the high temperature made the huge tanks with alcohol explode. About one Million litres of Absinth poured across the plant, down the sewer system and straight into the river Doubs. The river turned white and smelled of anise.
Two days later, André Berthelot visited the Source de la Loue more than 15 km from Pontarlier, on the other side of a high mountain ridge. While enjoying the romantic atmosphere at the clear spring, he suddenly noticed a change. The water turned milky, and a smell of anise filled the air. He knew this smell from the pub, but he had to take a mouthfull, to believe it: The water of the big spring turned into a free apéritiv! It is not handed down, if he filled his water-bottle...
This story was heard by the founder of modern speleology, E. A. Martel, and nine years later he made a dye tracing experiment. He found a swallow hole in the bed of river Doubs and added a strong, non-toxic, green colour. 64 hours later, the Source de la Loue turned green. The connection of the Loue and the Doubs across the mountain ridge was proven and the dye tracing of groundwater invented.
But now the next act in this play started: the owners of some small mills along the Doubs had problems with a strange lack of water for many years now. When the water level was low there was not enough water to operate the mills, although the river had enough water above Pontarlier. And the situation worsened every year. But as they learned of the Ponors, they had an idea. They searched for the swallow holes at low water and simply filled them with concrete. So they blocked them successfully and the water stayed in the Doubs.
But now the residents along the Loue had problems with missing water. And so the case came before the court and a Solomonic decision was made: The already sealed ponors may remain as they are, but new changes to the water course will be penalised. Obviously a fair solution because both parties were equally unhappy with it.
This kind of story happened in many karst areas all over the world. Another famous one is the Donauversickerung (Danube Sink), where the water of the young Danube sinks to reappear in the Aachtopf (Aach spring). But Pernod was never used for dye tracing experiments again!