Thousands of years ago, the Eifel was a very active volcanic area. The circular, partly water-filled mars that can be found there also date from this time. Near the municipality of Boos is a double mare, which was formed explosively about 35,000 years ago when magma and water met. Topologically, it is two round shallow hollows in the landscape, one of which is a dry maar, the other a pond. Next to it, on a hill, the Schneeberg, stands a 25-metre-high observation tower from which one has a very beautiful view over the hilltops of the Eifel.
