The oldest rocks in the region can be seen in the former Burer Millen quarry: the red sandstones from the period of coloured sandstone. The color comes from the iron contained in the stone. The Burer Millen quarry is the only location in the lower Sûre valley where this stone was mined.
The coloured sandstone lies on the surface here, because the geological layers bulge particularly high up and form a saddle ("Born saddle"). As the river Sûre cut down deep in the soil, the younger layers of rock from the time of the shell limestone (yellowish green sandstones, marl with plaster layers and dolomite) were removed and the red sandstone layer underneath appeared.
Mining took place in the small quarry above the PC 3 cycle path in the middle of the 20th century (you may enter the quarry at your own risk). The mined material was removed by rail and then used as a building stone.
An information board along the bike path gives information about the history of the quarry.