The Pulvermaar, with a depth of more than 80m in places, is the "deepest eye” and also the deepest lake north of the Alps. These 80 meters are only a fraction of the original depth of the crater which geologists estimate at 300m. The power of numerous explosions over a period of several weeks or months must have been breathtaking for the people of the Eifel, turning day into night and leaving a 100m high wall of debris, ash and stones (lapilli). Later on, more than 13 million cubic meters of water collected within the funnel. Because of its great depth, the temperature remains a constant + 4 C.
The Strohner Märchen and also the Dürremaar on the other side of Gillenfeld with their rare moor vegetation are proof of the transition from ‘Maar’ to land. The Immerather Maar dried out, becoming arable land during the 1940’s, and was used as a potato field. Later on, for touristic reason, new consideration was given to the area as an important natural land form and further farming was curtailed..
Nowadays a walk starting at the Pulvermaar, past the Römerberg, a true volcano with scoria, to the Strohner ‘dry-Maar’ and further on to the Immerather Maar or Immerather Risch shows all the changes a ‘Maar’ goes through - from being a deep lake to becoming a land-filled hollow.
At some future time there might be another Ice age and some time later another volcano might explode as the gases (the Plume) deep down are still hot. At the moment science can neither explain nor predict how and when this heated matter will be raised to the surface and ejected. The proximity of vapours, superheated and under pressure, pushing their way up at different times and different speed lets us assume that the same areas of vulnerability will be affected once more. For hundreds of thousands of years volcanoes have left their mark in the triangle of Gillenfeld – Strohn – Immerath, and this will recur again in the far distant future.