The formation of the Kaiserstuhl volcano during the Tertiary was the climax and at the same time the end of volcanic activity in the Upper Rhine Valley Rift. Volcanism started as early as the Cretaceous Period. Volcanic landforms include heavily eroded volcanic vents. The Kaiserstuhl is the only larger volcano from this period in the rift valley. Geologically the Kaiserstuhl can be divided into two parts: the sedimentary and volcanic part. Due to these peculiarities the Kaiserstuhl has been labeled one of the most important national geotopes.