A Crucial Site in the Argument Between Neptunists and Plutonists: Reopening of the Historical Adit in the Komorní hůrka (Kammerbühl) Volcano After 180 Years

A small, inconspicuous scoria cone in western Bohemia, known as Komorni hůrka Hill, played a crucial role during the controversy between Plutonists and Neptunists over the origin of rocks in the first half of the nineteenth century. The year 2017 represents the 180th anniversary of one successful resolution of this debate: at the instigation of J.W. Goethe, adits were dug into this volcano to access its feeding system in order to observe whether volcanoes were fed by burning coal seams, or feeder dikes of magma. The adits into Komorni hůrka Hill were the first large earth-works with a solely scientific goal and with no commercial mining purposes. The basaltic feeder exposed in the adits decided definitively in favour of the Plutonists after decades of ongoing arguments with the Neptunists. Here, we summarize the overall history of this small volcano. A recently conducted ground geophysical survey confirmed the position of historical adits, marked on several archive sketches. The geophysical data, comprising ground magnetometry, electric resistivity tomography and refraction seismic profiles, also revealed the internal structure of the volcano, including the position of the feeder dike and the geometry of a lava flow emitted from the crater. With the position of these historical adits confirmed by geophysical survey, excavations can safely reopen these historical earth-works and provide access to a wider public. Komorni hůrka could then serve as an educational geosite to exhibit the structure of a small monogenetic volcano, as well as illustrating a stage in the history of Earth Sciences.