The quartz diorites (crystalline rocks) of the Felsenmeer (sea of rocks) were formed about 340 million years ago in the depth of more than 12km. During that time, two ancient continents collided and the ancient Odenwald was situated directly in the collision zone. Due to the collision rock melts have been formed which rised up to the upper Earth crust and cooled by generating huge crystalline rock bodies. The Quartz diorites of the "Felsenmeer" also belong to this ancient collision zone.