The former border posts (FDP) delineated forest areas owned by the prince bishop of Liège. Residents were not allowed to harvest trees in these forests. With the arrival of iron forges the demand for charcoal only went up and deforestation became a problem. In 1878, to protect the forests from illegal tree harvest, the Principality placed stone pilars to demarte the forest reserves. At least 480 stone pillars were placed at 13 forest reserves in the Principality, including those near Jalhay and Sart. Stone pillars replaced the original wooden posts.
The old border posts (FDP)