The Earth Pyramids on the Renon/Ritten

The formation of the earth pyramids on the Ritten, the local mountain of Bolzano, is due to the interplay of several factors. One is the special nature of the soil, as it consists of late glacial moraine clay, i.e., deposits of the large Eisack valley glacier and various local side glaciers from the last ice age. This moraine clay is rock-hard when dry, but turns into a clayey mush when mixed with water.

After landslides and erosion have removed the protective soil and plant cover, the moraine clay quickly softens in the rain, and the viscous mush begins to slide and flow downhill. Wherever larger boulders are found in this clay, the material underneath remains dry and solid. In the interplay of rain and dry seasons, the steep slopes are increasingly furrowed, and a tangle of cones and pyramids seemingly grows out of the ground over time.

Like columns, sharp teeth or inverted icicles, these bizarre structures rise up, some up to 30 m high. Similar earth pyramids can also be found in Percha in the Puster Valley, in Steinegg, in Tyrol, Italy, Bulgaria, Switzerland, and Italy. However, the earth pyramids at Ritten are the tallest and most varied in Europe, and it is no coincidence that they have become the emblem of the Ritten municipality.

How long it takes for such an earth pyramid to form, and how old it can get, is difficult to say. Too many different factors play a role. However, it is certain that the end of an earth pyramid has come as soon as the protective capstone at its peak detaches and falls down. Then it is irrevocably doomed to destruction, as nothing more hinders the destructive power of water.

This transience also contributes to the great appeal of the earth pyramids, as they are constantly transforming and offer visitors a new picture each time. The color also changes depending on the time of day and the incidence of light, so that one always gains new impressions.

Earth pyramids can be found on the Ritten in the Finsterbach ravine between Lengmoos and Mittelberg, in the Katzenbach ravine near Oberbozen, in the Gasterer ravine in Unterinn, and in the hard-to-reach Gasserlahn near Oberinn. They can be reached, for example, on a leisurely excursion with the Ritten railway and the hiking trail 24. Lama trekking tours to the earth pyramids are also offered.