The Blautopf (German for ''Blue pot'') is a spring that is considered the source of the river Blau in the

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

landscape on the

Swabian Jura The Swabian Jura ( , more rarely ), sometimes also named Swabian Alps in English, is a mountain range in Baden-Württemberg, Germany, extending from southwest to northeast and in width. It is named after the region of Swabia. It is part of th ...

's southern edge. It is located in Blaubeuren,

Alb-Donau-Kreis Alb-Donau-Kreis is a (district) in Baden-Württemberg, Germany. It is bounded by (from the south and clockwise) the districts of Biberach, Reutlingen, Göppingen and Heidenheim, the two Bavarian districts Günzburg and Neu-Ulm, and the city ...

Baden-Württemberg Baden-Württemberg ( ; ), commonly shortened to BW or BaWü, is a states of Germany, German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million i ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

(approximately west of

Ulm Ulm () is the sixth-largest city of the southwestern German state of Baden-Württemberg, and with around 129,000 inhabitants, it is Germany's 60th-largest city. Ulm is located on the eastern edges of the Swabian Jura mountain range, on the up ...

Description

It forms the drain for the Blau

cave Caves or caverns are natural voids under the Earth's Planetary surface, surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance undergrou ...

system; the river Blau after flows into the river

Danube The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...

in the city of Ulm. Because of its high water pressure, the spring has developed a funnel-like shape with a depth of 21 metres (69 ft). The water's peculiarly blue color, varying in intensity depending on weather and flow, is the result of physical properties of the nanoscale

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

particles densely distributed in the water. They cause

Rayleigh scattering Rayleigh scattering ( ) is the scattering or deflection of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation. For light frequencies well below the resonance frequency of the scat ...

of light, preferentially scattering the blue color of the visible light. A similar effect is observed at the Blue Lagoon near

Reykjavík Reykjavík is the Capital city, capital and largest city in Iceland. It is located in southwestern Iceland on the southern shore of Faxaflói, the Faxaflói Bay. With a latitude of 64°08′ N, the city is List of northernmost items, the worl ...

, where the color originates from nanoscale

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

particles.Lonely Planet Best of Germany (Travel Guide), 2019. Benedict Walker, Kerry Christiani, Marc Di Duca. 324 pag. , On the banks of the Blautopf is located a hammer mill driven by the water of the spring. A film documenting the exploration of the cave is shown at the same location.

Geology

The Blautopf is a spring in a

environment. One characteristic of a karst environment is that water, which drains quickly through the limestone in one area, surfaces in another. Karst environments only have subterranean drainage, and there are no bodies of water above ground. Therefore, the size of the Blautopf depends greatly on the level of rainfall, though it never entirely dries out. The Blautopf is the second largest spring in

, after the

Aachtopf The Aachtopf () is Germany's biggest karst spring, south of the western end of the Swabian Jura near the town of Aach, Baden-Württemberg, Aach. It produces an average of 8,500 litres per second. Most of the water stems from the River Danube whe ...

. Over millennia, subterranean water has created a huge system of caves in the area. Prominent examples are the '' Blauhöhle'' (Blau-cave), discovered by Jochen Hasenmayer in 1985, and the ''Apokalypse'' (Apocalypse), discovered on 23 September 2006 by Jochen Malmann and Andreas Kücha, members of the ''Arbeitsgemeinschaft Blautopf'', a club dedicated to the exploration of the Blautopf's cave system. While the Blauhöhle is completely filled with water for a length of about 1,500 metres (approximately 4,935 ft), the Apokalypse is dry; because of its dimensions—170 metres long, 50 metres wide, 50 metres high—it is a special feature of the region.

Diving

The entry to the Blauhöhle lies at a depth of about 22 meters (about 70 ft). Therefore, access is restricted to experienced and well-trained divers. In the 1980s, city authorities were forced to prohibit diving in the Blautopf after several accidents, including some fatal ones. Permission to dive in the Blautopf has only been granted to a few organizations: among them, the ''Arbeitsgemeinschaft Blautopf'', a group of scientific speleologists led by Jochen Hasenmayer, and rescue services. The most recent fatal accident occurred in 2003, killing Bernd Aspacher, a member of Hasenmayer's team.

Legends

Numerous

legend A legend is a genre of folklore that consists of a narrative featuring human actions, believed or perceived to have taken place in human history. Narratives in this genre may demonstrate human values, and possess certain qualities that give the ...

s and

folk tale Oral literature, orature, or folk literature is a genre of literature that is spoken or sung in contrast to that which is written, though much oral literature has been transcribed. There is no standard definition, as anthropologists have used va ...

s refer to the Blautopf. Its characteristic colour was explained by the account that every day someone would pour a vat of ink into the Blautopf. Another myth stated that every time someone tried to measure the Blautopf's depth with a leaden sounding line, a water nix stole the sounding line. Therefore, it was not possible to determine the depth of the Blautopf. Because of this tale, there is a rock called ''Klötzle Blei'' ("little block of lead" in the local dialect) in the vicinity of the Blautopf. A well-known

tongue-twister A tongue twister is a phrase that is designed to be difficult to articulate properly, and can be used as a type of spoken (or sung) word game. Additionally, they can be used as exercises to improve pronunciation and fluency. Some tongue twisters p ...

in the Swabian dialect told to local children, refers to this rock: :''Glei bei Blaubeira leit a Kletzle Blei'' – :''´s leit a Kletzle Blei glei bei Blaubeira'' Standard High German: :''Gleich bei Blaubeuren liegt ein Klötzchen Blei'' – :''Es liegt ein Klötzchen Blei gleich bei Blaubeuren'' English Translation: :''Near Blaubeuren, there lies a block of lead'' – :''There lies a block of lead near Blaubeuren'' The novelist and poet

Eduard Mörike Eduard Friedrich Mörike (; 8 September 18044 June 1875) was a German Lutheran pastor who was also a Romantic poet and writer of novellas and novels. Many of his poems were set to music and became established folk songs, while others were used b ...

incorporated this

folklore Folklore is the body of expressive culture shared by a particular group of people, culture or subculture. This includes oral traditions such as Narrative, tales, myths, legends, proverbs, Poetry, poems, jokes, and other oral traditions. This also ...

and other tales into the romantic

novella A novella is a narrative prose fiction whose length is shorter than most novels, but longer than most novelettes and short stories. The English word ''novella'' derives from the Italian meaning a short story related to true (or apparently so) ...

''Das Stuttgarter Hutzelmännlein''. They were woven into the background story of a journeyman travelling from

Stuttgart Stuttgart (; ; Swabian German, Swabian: ; Alemannic German, Alemannic: ; Italian language, Italian: ; ) is the capital city, capital and List of cities in Baden-Württemberg by population, largest city of the States of Germany, German state of ...

to Blaubeuren. In particular, the story of the ''Schöne Lau'', a

mermaid In folklore, a mermaid is an aquatic creature with the head and upper body of a female human and the tail of a fish. Mermaids appear in the folklore of many cultures worldwide, including Europe, Latin America, Asia, and Africa. Mermaids are ...

, and her husband, a male water-nix from the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

, is told in great detail. Because the Schöne Lau could not laugh, the nix punished her by confining her to the Blautopf, and only allowing her to have still-born children. He would only allow her to return and give birth to a living child once she had laughed five times. In the end, the landlady of the

inn Inns are generally establishments or buildings where travelers can seek lodging, and usually, food and drink. Inns are typically located in the country or along a highway. Before the advent of motorized transportation, they also provided accomm ...

''Nonnenhof'' came to her aid. ''(The complete

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

text is available a
Eduard Mörike: Die Schöne Lau
)''

References

Bibliography

External links

Homepage of the Arbeitsgemeinschaft Blautopf (English version available)

Homepage of the city of Blaubeuren (in German)

Film taken at Blautopf
{{Authority control Springs of Germany Karst springs Karst formations of Germany Lakes of Baden-Württemberg Landforms of Baden-Württemberg Caves of Germany Alb-Donau-Kreis