Palsen
A special feature of the Eifel and the High Fens is the occurrence of palsy structures. These are circular or elongated depressions, which were caused by thawing of Eislinsen. In the weathering rind, ice crystals accumulated in the last glacial period, which in time grew into large ice lentils. The earth above the lenses continued to bulge, leaving a mound above each lens. Similar phenomena can still be found to a great extent in the Arctic regions or to a lesser extent in the humpback meadows in Iceland or in the Alps. The uppermost layers of the Eislinsen thawed by the warming at the turn of the Pleistocene to the Holocene. The earth that covered the lenses slid sideways so that the ice became free and could melt completely. In this way, round or oval depressions were created, the palses, which were surrounded by an adumbrium and filled with water. These naturally formed waters silted up over time, and fens formed within the ring-shaped earth wall. The milieu in these waters was mostly acidic, as the weathering of the liberated Cambrian Revin layers released sulfuric acid. So good conditions for the growth of peat mosses and thus for a bog vegetation, which replaced the fens.
Today in the Eifel, e.g. in Mützenicher Venn, as well as in the Hohe Venn still to find some of these structures. In the interior of the Palsen is still often a moor vegetation with peat mosses (Sphagnum sp., Especially S. paillosum and S. fallax), sundew (Droserea rotundifolia), rosemary heath (Andromeda polifolia) and the bog berry (Vaccinium oxycoccus). In contrast, plants that grow in arid areas of raised bogs grow on the mound. This includes e.g. the heather (Calluna vulgaris). The pals are especially beautiful in the Brackvenn and in the Hatsicher Venn. Brackvenn and Hatsicher Venn lie almost directly next to each other and can be combined well.