Where the mountains begin …

With its steep hillsides, fast-flowing streams and narrow, winding paths, Zuid-Limburg is, we believe, where the mountains really begin. Not only that, it is home to the Dutch Mountain Film Festival. Foreign visitors might mistakenly believe that this is NOT the Netherlands. That is largely down to its atypical Dutch landscape.

Of course, its hills and valleys are very much a result of the geology. For the most part, the underlying rock is limestone dating from the Cretaceous period, the remnants of a tropical sea from 70 million years ago. The region around Heerlen and Aachen lies on the northen fringes of the Ardennes massif and the Eifel plateau. To the north are the lowlands of the Rhine-Meuse delta region, part of the North Sea Basin. Both the Ardennes and the Eifel form part of the Rhenish Massif.

The region around Heerlen and Aachen is, in fact, an extensive limestone plateau which has been incised over the millenia by rivers and streams, resulting in an upland scenery characterised by steep hillsides with terraces. This plateau is still subject to an upward shift. It pivots, as it were, around the Felbiss fault line which runs from Aachen and past Kerkrade and Brunssum towards the north-west. From time to time, there are small tremors along this fault line, such as occurred in Aachen in 2021.

Limestone is not the only rock present. Fine-grained sand from the Miocene forms the basis for the silversand pits which can be found to the north of Heerlen. During the last Ice Age, the landscape was blanketed by a rich layer of loess, which can turn footpaths into mudbaths after a heavy shower.

Kunrade limestone is unique

In May 2024 a new study investigating the geology of Zuid-Limburg was published in the Netherlands Journal of Geosciences. In the paper, Maateus Kroth and his fellow researchers argue that Kunrade limestone should be given the status of a formation, a body of rock which has a distinct lithology, separate from adjacent bodies of rock. What locals in the region have already known for a long time, was finally confirmed by the scientific community: Kunrade limestone and the plateau it forms are unique.

Up until now, Kunrade limestone was considered to be part of the Maastricht Formation. In the past, much research took place in the Maastricht region and even led to spectacular discoveries, such as that of the Mosasaurus. More recent research has focused on a comparison of drilled bores. It was on the basis of the findings of these that the researchers decided to give Kunrade limestone a sparate status.  The simplified geological map in the article pinpoints the exact location of the Kunrade Formation, in which the Land van Kalk (literally ‘land of chalk’) can clearly be identified.

This limestone formation provides soils which are suitable for the cultivation of fruit and vines. The pastures between the churches and quarries of Kunrade limestone are also home to rare species of fauna and flora. For those in search of peace and quiet, this part of Limburg offers plenty of scope for hiking, cycling and culinary discoveries. For more information, check out the following (in Dutch): landvankalk.com.