Mardelles, "small maars", are small, mostly water-filled depressions without outlet. They are typical in marl landscapes which can be found around Mompach, or on marl surfaces on the Luxembourg sandstone around Consdorf. When gypsum lenses, lime lenses or dolomite are dissolved in the subsoil by inflowing water the surface above it sinks in. Most of the resulting depressions fill with rainwater. However, some mardells are also of human origin as marl was mined in pits for example.
Mardelles are "sediment traps" and provide excellent conditions for plant and wood remnants. Thus, far-reaching statements can be made on vegetation and land use history, soil erosion and climate change. They also provide a habitat for specific animal and plant species.
The Mardelles are located directly on thematic hiking trail Joffer Margot.