Spring alluvial cone
Alluvial spring cones are a special feature of the Karst of the Paderborn plateau , as they only occur there. These are temporary sources on shield-shaped elevations. They formed in the valley floors of the Alme and Altenau , among other places . In total, there are 17 of these alluvial springs in the area of the Paderborn plateau. These have a height of up to 2 meters and a diameter of up to 50 meters. Many of these have now been completely or partially destroyed by road construction and drainage. They were discovered for the first time in 1955 by students at the Mauritius High School during a project to observe the alpine pastures. The largest alluvial spring cone is in the Mental near Henglarn .
Emergence
A spring alluvial cone is created by clayey and silty weathered rock that has been washed in by precipitation . This is washed into sinkholes ( sinkholes ) and rock cracks when there is heavy rainfall . Turbulence and water pressure prevent the water below the ground from clearing. This water comes back to the surface of the earth in springs in the valleys. There the suspended matter settled in a circle around the opening of the spring on the grass. This grass grows through the embankment and so the alluvial spring cone keeps increasing. Alluvial spring cones can only arise in meadows and pastures, not in forests. The beginning of their creation is therefore estimated at the end of the Neolithic .
Categorization
From a physiogeographical point of view, all spring alluvial cones lie in the floodplains of temporary dry valleys. They mostly appear in groups, but also singularly. Four types of alluvial spring cone can be distinguished:
- a hill without a clearly localizable main outlet point (s) for the water. The mound is completely soaked in the action of the spring.
Example: Two spring alluvial cones in Sauertal near Ebbinghausen (Lichtenau) - a hill with a clearly locatable, chimney-shaped opening, with a diameter of a few centimeters, from which the water gushes out when the spring is active.
Example: an alluvial spring cone in the Almetal near Wewelsburg - a hill with spring funnels that reach a diameter of 5 to 6 meters and a depth of 1.5 to 2.5 meters.
Example: The NNW-SSE spring alluvial cone series near Niederntudorf - a hill with several, clearly localizable source outlets ( Quickspringe ), from which the water gushes out like a fountain when the source is active.
Example: A singular alluvial spring cone in the Mental near Henglarn
Occurrence
Source groups
- in the Mental near Henglarn along the Menne - completely preserved
- between Henglarn and Atteln along the Altenau - does not yet appear morphologically or hardly at all
- in the valley meadow of the Alme (Lippe) near Niederntudorf - completely preserved
- between Niederntudorf and Alfen (Borchen) in the Almetal - partially destroyed
- between Niederntudorf and Wewelsburg in the Almetal - partially destroyed
- in the Sauer Valley near Ebbinghausen (Lichtenau) - partially destroyed
Singular alluvial spring cone in the Mental near Henglarn
It is the largest single alluvial spring cone on the Paderborn plateau with a diameter of around 50 meters and a height of 2.5 meters. The volume of the cone is around 3000 m 3 . In the center of the cone, up to seven Quicksprings flow at times, which together with other small water outlets pour out up to 25 liters / second on the flanks of the cone. The water temperature fluctuates only slightly between 8 and 9 degrees Celsius over the course of the year and allows grass to sprout and the snow to melt even in winter. The water in the Quickspringe carries up to 0.8 grams / liter of suspended matter, most of which settles in the immediate vicinity of the exit points. The water gushing out of the hill flows partly in small rivulets, partly over a large area. The water gathers at the foot of the hill and flows down the valley parallel to the Mennebach, about 200 to 250 meters and finally seeps into the pasture. The alluvial spring cone in the Mental is an exception to the other cones. This is in the middle of the valley and not like the cones in the Almetal on the southeastern edge of the valley. Another peculiarity is the large number of spring outlets on one and the same hill.
Rows of alluvial spring cones in the floodplain of the Alme near Niederntudorf
It is the largest and at the same time the best preserved group with spring funnels. The first group, which consists of four large cones up to 2 meters high with swell funnels, lies in a row facing NNW-SSE. The cones have grown together to form a flat sediment ridge. The northernmost cone is no longer active and therefore no longer has a source opening. The other three have wells up to 2.5 meters deep. Another group of the extraordinary springs is about 500 meters away and is arranged in a WSW-ONO row. The individual, up to 1 meter high cones, however, are significantly smaller than the hills of the NNW-SSE series. Only one of these cones has a small spring funnel, the other hills have no clearly localizable main outlet points for the water. In humid seasons, the karst groundwater rises slowly until it finally overflows from the funnels and makes its way to the alpine pasture. Parallel to the rows of alluvial spring cones near Niederntudorf in rainy times, so-called Quickspringe (temporary springs) pour off large amounts of water together. The Quickspringe in the floodplain of the Alme are partly right next to the WSW-ONO row of alluvial spring cones.
- Alluvial spring cone near Niederntudorf
A spring alluvial cone from the NNW-SSE series in the dry season near Niederntudorf .
The NNW-SSE spring alluvial cone series near Niederntudorf; the southernmost cone with clearly visible drainage.
The middle cone from the WSW-ONO directed row near Niederntudorf; the hill elevation is clearly visible.
The southernmost cone from the WSW-ONO directed row near Niederntudorf; the source funnel in the foreground.
swell
- Wolfgang Feige, Karl-Heinz Otto: Spring alluvial cone - a little-known spring type and surface shape in the karst area of the Paderborn plateau. In: Decheniana 158, pp. 145-164 (2005). The most recent and most comprehensive publication on alluvial water cones.
- Wolfgang Feige: Valley development and karstification in the chalk area of the Alme. Series of publications by the Geographical Commission for Westphalia, Spieker, regional studies contributions and reports, Issue 11 - Contributions to Physiogeography II, pp. 3–66, also: Münster, Dissertation, 1961
- Wolfgang Feige: Landscape Guide - The Bürener Land. Büren 2008, series Wir an Alme und Afte des Heimatverein Büren eV (publisher), p. 28
- Wolfgang Feige, Karl Heinz Otto: The spring alluvial cone in the Mental (Paderborn plateau). In: Geographical Commission for Westphalia (Hrsg.), GeKo Aktuell 1/1999
- Wolfgang Feige: The alluvial spring cones in the Almetal - they were discovered by sextans near Niederntudorf. In: Die Warte - Heimatschrift for the Paderborn and Höxter districts - No. 52, Christmas 1986
Web links
Coordinates: 51 ° 37 ′ 34.5 " N , 8 ° 41 ′ 16.3" E