Slate mining in the Raumland area has been documented since the 16th century. The quality of the stone, which was mainly used for roofing, was so special that it was mined in eleven pits. However, alternative materials made the market so difficult that the pits were all closed by the middle of the 20th century.
The area around the Hörre I mine with its extensive tunnel system subsequently became an important refuge for bats. Ten species of bat have been recorded here, hibernating at 0-9 degrees between late summer and spring.
A wide variety of birds find breeding grounds, such as the eagle owl, Central Europe's largest owl, which almost became extinct in Germany due to hunting in the 19th century.
And the slate heaps that still exist provide an ideal habitat for many insects and reptiles, such as the smooth snake, as well as warmth-loving plants such as rock stonecrop and golden thistle.
