Attendorn-Elsper double trough
The Attendorn-Elsper Doppelmulde is a tectonic double depression that lies on both sides of the Lenne and immediately south of the Ebbe-Homert threshold in the Sauerland district of Olpe ( North Rhine-Westphalia ). It is named after the places Attendorn in the southwest and Elspe in the east of the valley, other peripheral locations are Fretter in the northeast and Mecklinghausen in the south.
In terms of natural space, the depression, also referred to as Attendorn-Elsper Kalksenken, is assigned to the Sauerland depressions (main unit 335) under the code number 335.2 in the main unit group Süderbergland .
Location, boundaries and structure
The Attendorn-Elsper Doppelmulde is located in the Olpe district in the urban and community areas of Attendorn (south-west), Finnentrop (north) and Lennestadt (south-east). It consists of two depressions trending northeast, separated from one another by small slate ridges and connected to one another in a corridor southwest of the Lenne valley , near Silbecke .
Bigge Fretter Depression
The north-westerly of the two depressions, the Bigge-Fretter depression , stretches upstream of the Bigge from the northern edge of the Bigge lake via Attendorn to the confluence with the Lenne near Finnentrop. From there it stretches over Bamenohl and Weringhausen further northeast to the valley of the Fretterbach , along which then over Fretter to immediately before Serkenrode . On the left of the Lenne are the towns of Ennest and Heggen , on the right of the Fretter and the town of Schönholthausen in the area of the valley.
Helden-Elsper Senke
The Helden-Elsper Senke , the southeastern of the two sinks, stretches from the southwest along the Repe from Mecklinghausen via Helden to the confluence at Grevenbrück , then further northeast to follow the Elspe to Elspe and finally the Bremkerbach until the now very narrow Valley ends at Altenvalbert . On the left of the Repe there is also Dünschede in the depression, which on the right of the Unterelspe also includes Sporke , Hespecke and Melbecke .
Limiting mountain ranges
In the south-west, the Dünscheder Sattel as part of the Mittelbigge mountain range separates the two depressions. From its base, the Reper Höhe ( 472.8 m ) west of Repes , it gradually levels off over Sonnenberg ( 458.5 m ) and Geinen ( 427.6 m ) to barely more than 340 m at the saddle southwest of Silbeckes.
To the north-east of the Silbeck Corridor there is a narrow south-west extension of the Kobbenroder Riegel made of Kulmkiesel schist and limestone, which is broken in its south-west, separating the Dumberg ( 407.3 m ) from the Lenne at around 238 m . It follows u. a. Mondschein ( 434 m ), (Großer) Hemberg ( 507.9 m ) and Prinnemeckeskopf ( 519 m ).
The south-west arm of the aforementioned Kobbenroder Riegel, a more montane part of the Sauerland valley, which reaches a maximum of 500 m , forms the southeastern border of the Helden-Elsper valley. It flanks the even higher South Sauerland Rothaarvorhöhen , which adjoins it further southeast, with the Saalhauser Mountains (up to 688 m ), which frame the even higher Rothaargebirge - at some distance .
In the north-west, on the other hand, the ebb (up to 663 m , but less than 500 m near the valley ) and, to the right of the Lenne, the Lennegebirge (up to 656 m , on the Kathenberg north of Serkenrode 580.8 m ) right up to the Bigge-Fretter-Mulde.
Geological origin
At its core, the Attendorn – Elsper double trough represents a limestone reef. It emerged from an atoll that was compressed and thus pushed up by the tectonic shift.
Later on, the upturned soil was removed again through erosion , bed load and other influences. The drainage of the resulting landscape area - through the Lenne - dug itself into the mountains. At first, the “Lenne” meandered very strongly, and today's plateaus formed along the river. The limestone reef of the Attendorn-Elsper Mulde was only breached when the Lenne sank more strongly into the mountains and today's river bed was formed. This is easy to see if you look from Sporke in the direction of Dünschede . Here you can see the extension of the limestone valley towards Helden very clearly, which is only separated by the Lenne gorge.
Numerous caves were able to form in the mass limestone of the Upper Middle Devon. Triggered by tectonic processes ( faults and displacements of the mountains) that caused the rock to form fissures, most of these caves developed as a result of corrosive weathering processes (so-called karstification ). Rainwater that seeped away from the surface and then penetrated into the limestone through the fissures loosened the limestone. Later, in the cave spaces created in this way, sintering formed on the cave ceilings, walls and floors due to the degassing of carbon dioxide in the cave atmosphere . The water that constantly drips off at the same place, which carries dissolved calcite with it, forms the stalactites hanging from the ceiling and the stalagmites growing on the floor over time .
The largest stalactite cave in this former limestone reef is the Atta cave in Attendorn. There are other caves along the Biggetal all the way to Finnentrop . On the opposite axis, caves were formed in the Repe and Elspetal , as well as in the faults of the Lenne gorge at Borghausen , Sporke and Hespecke .
Individual evidence
- ↑ Geographical survey of the country: The natural units on sheet 110 - Arnsberg (Martin Bürgener 1969) - Federal Institute for Regional Studies, Bad Godesberg (→ maps )
literature
- Willi Ziegler u. a .: Geological map of North Rhine-Westphalia 1: 25,000. Explanations for sheet 4813 Attendorn . Krefeld 1978.
Web links
- Natural area maps from single sheets 1: 200,000 of the Federal Institute for Regional Studies - the Attendorn-Elsper double trough is unit 335.2 on sheet 110 - Arnsberg
Coordinates: 51 ° 8 ′ 37.7 ″ N , 7 ° 59 ′ 16.4 ″ E