The Randecker Maar is a

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

– a

volcanic crater A volcanic crater is an approximately circular depression in the ground caused by volcanic activity. It is typically a bowl-shaped feature containing one or more vents. During volcanic eruptions, molten magma and volcanic gases rise from an und ...

about wide. It is in the

Swabian Jura The Swabian Jura (german: Schwäbische Alb , 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 ...

mountains, in the municipality

Bissingen an der Teck Bissingen is a municipality in the district of Esslingen in Baden-Württemberg in southern Germany. Geographical location Bissingen lies at the foot of the Swabian Jura, the district Ochsenwang on the Alb plateau. The municipality covers an ...

near Stuttgart and was formed around 17 million years ago. A

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...

formed in the crater and its bed is now a layer of the

early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was p ...

in which many

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s have been found. Nowadays, the crater is drained by the Zipfelbach brook and so there is no longer a lake. The northeastern wall of the crater has eroded and opens to lower ground. This forms a natural pass for the seasonal migration of birds and insects as they fly up and over the alps. This makes it a good point for observing these creatures and so an observatory was established there in 1969 by ornithologist Wulf Gatter – '' Forschungsstation Randecker Maar e.V.''. The maar and

gorge A canyon (from ; archaic British English spelling: ''cañon''), or gorge, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency to c ...

of the Zipfelbach were designated as a

nature reserve A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, or features of geological or ...

by local ordinances in 1971 and 1990 to preserve the landscape and its

fauna and flora In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

for science and popular enjoyment. The area conserved is now . File: Randecker-Maar NSG Schwaebische-Alb.jpg, A view to the NNE showing the pass and the

Limburg Limburg or Limbourg may refer to: Regions * Limburg (Belgium), a province since 1839 in the Flanders region of Belgium * Limburg (Netherlands), a province since 1839 in the south of the Netherlands * Diocese of Limburg, Roman Catholic Diocese in ...

beyond File: Randecker Maar - panoramio.jpg

References

Further reading