Bolderberg Nature Reserve

The Bolderberg nature reserve is part of the oldest protected landscape in Flanders. The hill is a living testimony to what Flanders once looked like 3.5 to 11 million years ago: a great sea. The sand that was deposited then changed over time into hard iron sandstone due to weathering. In places where the soil was softer, such as in the valleys, the iron sandstone weathered or eroded. That is why the Bolderberg now towers nicely between the valleys of the Laambeek and the Bolderbergbeek about 20 meters above the surroundings and you have a beautiful view of the ponds and the castle of Terlaemen and you can enjoy the heather.

The Bolderberg is a witness hill and nature reserve near the eponymous town of Bolderberg in the Belgian municipality of Heusden-Zolder. It is located near the Circuit Zolder, Domein Bovy and the nature reserves Waterlozen and Wijvenheide.
The largest part of the hill - including the historic Kluis van Bolderberg - belongs to the private domain of Kasteel Vogelsanck. This part of the domain is accessible to the public. Another part is owned by Limburgs Landschap vzw and is managed as a nature reserve. This is a sub-area of the Laambeekvallei reserve and covers almost 70 ha. This reserve also includes the heathland on the Bolderberg known as the Gust Claesheide, named after the Bolderberg school principal Gust Claes (1927-1978), who did much to spread knowledge about and love for nature. At the bottom of the steeply sloping heathland, seepage emerges and one finds wet heathland and raised bog with, among other things, cotton grass, bog asphodel and bog myrtle. The tree frog also occurs there.
From the Kluis one has a special view of the ponds in the depths and the castle of Terlaemen.
(Wikipedia)

The hill is a living testimony to how Flanders once looked some 3.5 to 11 million years ago: a large sea. The sand that was deposited then changed over time through weathering into hard iron sandstone. In places where the soil was softer, such as in the valleys, the iron sandstone weathered or eroded. That is why the Bolderberg now stands beautifully between the valleys of the Laambeek and the Bolderbergbeek, some 20 metres above the surroundings. Source: limburgs-landschap.be/bolderberg