The wide valley of the Leuvenumse Beek (Leuvenum Brook) in the northern Veluwe originated from a lobe of the Riss (Saale) ice-sheet which pushed up the ridges bordering the depression (Fig. I). Fluvioglacial deposits (kame terrasses, Maarleveld 1962) are to be found on the margin of these ridges and in several places the cover sand or gravelly solifluction layer of the valley is underlain by a heavy stratified fluvioglacial clay (Crommelin & Maarleveld 1952). This layer is particularly moisture retentive, so that the overlying soil becomes soaked and marshy and overgrown with a carr association interspersed with grasses and sedges.