Sinkhole lake
| Sinkhole lake | ||
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| Geographical location | Hopsten , Steinfurt district | |
| Tributaries | none | |
| Drain | none | |
| Location close to the shore | Hopsten , Obersteinbeck and Uffeln | |
| Data | ||
| Coordinates | 52 ° 20 '57 " N , 7 ° 37' 29" E | |
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| Altitude above sea level | 44 m | |
| surface | 7 ha | |
| length | 320 m | |
| width | 120-140 m | |
| Maximum depth | 12 m | |
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particularities |
Lake in the Heiliges Meer nature reserve - Heupen |
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The Erdfallsee is one of the four large still waters of the Heiliges Meer - Heupen nature reserve in Tecklenburger Land ( Steinfurt district ). It was created on April 14, 1913 by a sinkhole that soon filled with water. Unlike the neighboring Great Holy Sea, it is located exclusively on the soil of the municipality of Hopsten .
Landscape around the lake
The Erdfallsee is located southwest of the state road 504 Ibbenbüren −Hopsten and the Great Holy Sea. The sinkhole lake is framed by heather areas and a few moor pools as well as smaller older and newer earth depressions. These depressions in the earth sometimes fill with water periodically depending on the depth . The deeper depressions are mostly filled with water all year round. The smaller heather pond is south of the sinkhole lake . The heather pond may not have been created by a sinkhole, but by sand blown in the sandy heather landscape . The Meerbecke flows east of the nature reserve towards Hopstener Aa . In the wider area around the lake, grassland areas are integrated into the nature reserve. In addition to their own need for protection, they should also protect the lakes from the introduction of nutrients.
Landscape before the lake was created
Before the lake was created in 1913, a moor and heather landscape spread out in the area of what would later become the lake. At that time, the nutrient-poor areas were not suitable for intensive agricultural cultivation because the harvest yields would have been too low. So they were used extensively for grazing with sheep and for pest biting . In the heather there were birch trees and other frugal trees and plant species.
The moor, also called Hopstener Moor, intersected the subsidence area in the northeast and today forms a small, shallow bay in contrast to the deep subsidence basin.
Formation of the lake
The seven- hectare and twelve-meter-deep lake was created on April 14, 1913 between 6 and 7 p.m. by a sinkhole. Its emergence was accompanied by water leaks and water rises near the break-in point. On nearby farms, water is said to have gushed up in small jets up to 15 centimeters high. The water level of a courtyard well is said to have risen to 1.50 meters above ground level, but fell again the following day.
On the Little Holy Sea , a boy who was traveling in a boat had to leave the lake because the water began to billow and boil at 7 p.m.
The sinkhole was only discovered the next day. Initially, the collapse funnel was 20 meters deep and measured 120 to 160 meters in diameter. Through demolitions and silting up , it constantly changed its shape until it looks today.
It is assumed that the cause of the sinkhole was that salt , lime and gypsum were leached in the deeper subsoil . After the cavities became too large, they collapsed and the soil on the surface of the earth sagged. Such subsidence usually lasts for many years, so that only inconspicuous earth hollows arise. The unusual sudden collapse of the sinkhole lake is attributed to a fault line that is explained by faults in the nearby Schafberg .
The sinkhole attracted up to 6,000 visitors in the days that followed. The Kleinbahn Piesberg – Rheine had to cope with the influx of visitors with special trains to the nearby Zumwalde station. The owner of the site raised entrance fees to view the sinkhole during the crowd . Later, when the hole was filled with water, the rush of visitors subsided.
In the first few years after its creation, the water was still used for bathing. In today's nature reserve, however, bathing is prohibited. A part of the area in front of the lake is still accessible to visitors. A circular route is signposted there, which offers informative insights. However, the area is fenced in with barbed wire to guide visitors.
The waters
The water is very poor in lime and slightly acidic, which promotes biodiversity. The originally oligotrophic lake has turned into a partially mesotrophic body of water over time due to eutrophication . In addition to the natural causes, the surrounding arable land and the sea basin also contribute to this change. The now rare nutrient-poor habitats in and around the lake are being lost. Due to the nutrient entrainment, the lake in the nature reserve is the most rapidly changing body of water.
plants
The oligotrophic beachling communities are among the most valuable plants in the nature reserve . The also very rare water lobelia , which in the 1970s still occurred in the thousands in the lake, has meanwhile been pushed back considerably. The reeds found on the edge of the lake have suffered severely from muskrat bites in recent years and their occurrence has decreased significantly. The shore of the lake is largely designed as a sandbank . Alder forest and birch-oak mixed forest adjoin the shore zones . There are also extensive Gagel bushes.
See also
literature
- Fritz Runge : The natural monuments, nature and landscape protection areas of the Steinfurt district (= series of publications of the Steinfurt district. Vol. 2, ZDB -ID 582701-2 ). District of Steinfurt, Steinfurt 1982.
- Christa Tepe: The subsidence near Hopsten was a natural phenomenon that was much admired. In: Our circle. Yearbook for the Steinfurt district. 11, 1998, ZDB -ID 238980-0 , pp. 25-27.
