The Feldsee (also ''Feldbergsee'') is a

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

in southern

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 ...

at the foot of the Feldberg east of

Freiburg im Breisgau Freiburg im Breisgau or simply Freiburg is the List of cities in Baden-Württemberg by population, fourth-largest city of the German state of Baden-Württemberg after Stuttgart, Mannheim and Karlsruhe. Its built-up area has a population of abou ...

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 ...

. It is part of the

Southern Black Forest Nature Park The Southern Black Forest Nature Park () is located in Baden-Württemberg in Germany and covers an area of . As of 2018, it is Germany's largest nature park. History The Southern Black Forest Nature Park was established on February 1, 1999. The ...

Geology and earth history

The Feldsee is a tarn, around 97,500 m² in area and up to 32 metres deep. It was formed by

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

s of the last ice age. The largest tarn in the Black Forest, it is hemmed in on three sides by steep mountainsides up to 300 metres high. It is almost circular and has a diameter of between 350 and 370 metres. This area of highland at a height of , which is open to the northeast, enabled it to amass and retain the huge quantities of snow that were the cause of this armchair-shaped terrain with its steep back face, level floor and embankment of

moraine A moraine is any accumulation of unconsolidated debris (regolith and Rock (geology), rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a gla ...

at the front. The lake formed after the melting of the ice sheet behind the lines of heaped-up glacial debris.Dr. Wolfgang Fleck, Landesamt für Geologie, Rohstoffe und Bergbau
The Seebach stream, which rises between the Feldberg and Seebuck in the ''Grüble'', flows through the Feldsee, tumbling over the Feldsee Waterfall on the wall of the cirque, eventually becoming the '' Gutach'' at the far side of the Titisee. For several hundred thousand years this was the upper course of the ancient Danube (''Urdonau''), which flowed into the present-day

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 ...

near

Immendingen Immendingen is a municipality in the district of Tuttlingen (district), Tuttlingen in Baden-Württemberg in Germany located on the Upper Danube Nature Park, Upper Danube. It is famous for the Danube Sinkhole. Geography Immendingen is located on ...

and, for the last several ten thousand years has formed a headstream of the Wutach, which flows into the

Rhine The Rhine ( ) is one of the List of rivers of Europe, major rivers in Europe. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps. It forms part of the Swiss-Liechtenstein border, then part of the Austria–Swit ...

. Below the Feldsee, between the heaps of

, used to be another, smaller lake that, through the formation of

peat Peat is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. ''Sphagnum'' moss, also called peat moss, is one of the most ...

has silted up to become the present-day, botanically valuable bog of ''Feldseemoor''.

Nature conservation

Currently there is a general ban on bathing in the Feldsee. This is in order to protect a rare underwater fern, the spiny quillwort (''Isoetes echinospora''), that thrives in water 1–2 metres deep and only occurs in Germany in the Feldsee and Lake Titisee. This plant grows in lakes with cool, very clear water that are low in nutrients. Around the Feldsee is a so-called '' Bannwald''. This mixed forest is also protected and is allowed to grow naturally. It has been protected since 1937 and is the oldest nature reserve in Baden-Württemberg. The Feldsee Crags (''Feldseefelsen'') are out of bounds to climbers. The Feldberg rangers enforce these rules strictly. There are rare plants here like the alpine sow-thistle, Turk's cap lily, wolfsbane and

sundew ''Drosera'', which is commonly known as the sundews, is one of the largest genera of carnivorous plants, with at least 194 species. 2 volumes. These members of the family Droseraceae lure, capture, and digest insects using stalked mucilaginous ...

. Recently, a new species of bacteria was discovered in the lake and subsequently scientifically described. This new species, '' Polynucleobacter campilacus'' is named after the lake.Hahn MW, Koll U, Schmidt J, Huymann LR, Karbon G, Lang E (2018) ''Polynucleobacter hirudinilacicola'' sp. nov. and ''Polynucleobacter campilacus'' sp. nov., both isolated from freshwater systems, International Journal of Systematic and Evolutionary Microbiology 68(8):2593-2601 (http://ijs.microbiologyresearch.org/content/journal/ijsem/10.1099/ijsem.0.002880#tab2) Currently, it is not known, if this species is endemic to the lake or possesses a geographically broader distribution. ''P. campilacus'' is remarkable because of its relatively small genome size.

Access

There are no roads to the Feldsee; it can only be accessed on foot or by bicycle. The nearest car parks are 3–4 km away in Feldberg-Bärental (''Wanderparkplatz Kunzenmoos''), and on the Feldberg. The Feldsee is easily reached by bicycle from Alpersbach via the Rinken. The lake can be circumnavigated on a well-prepared path. 490 metres east of the Feldsee is the 300-year-old '' Raimartihof'' inn.

References

Literature

* Der Feldberg im Schwarzwald. Subalpine Insel im Mittelgebirge; mit Beiträgen von A. Bogenrieder, E. Liehl, E. Oberdorfer, G. Osche, W. Wimmenauer et al. (Photography: H. & K. Rasbach). – publ.: Landesanstalt für Umweltschutz Baden-Württemberg, Karlsruhe, 1982, (vergr.) * Der Schwarzwald. Beiträge zur Landeskunde; eds.: E. Liehl & W. D. Sick – 2nd edn., Verlag Konkordia, Bühl 1982, (vergr.) * August Vetter: Feldberg im Schwarzwald, Selbstverlag der Gemeinde Feldberg (Schwarzwald), 1982/1996

External links

{{wikisource, Feldsee
Legends about the Feldsee
Lakes of Baden-Württemberg Tarns of the Black Forest Breisgau-Hochschwarzwald LFeldsee