The earth pyramids of Renon

The earth pyramids of Renon are regarded as the most beautiful of Europe because of their height, their good condition and their variety. They are found in Finsterbach between Mittelberg and Lengmoos (earth pyramids of Klobenstein), in the valley of Katzenbachtal underneath Oberbozen and in the valley of Ganderbach near Unterinn (also called the white earth pyramids). Beginnings of new pyramids can be seen at Gasserlahn in Oberinn.

The earth pyramids of Renon are a geological peculiarity. Their formation dates back to the glacial era, when the glaciers deposited morainic material in this area. They consist of glacial moraine clay deposited by the main glacier of the valley of Valle Isarco as well as local tributary glaciers in the late ice age. Due to erosion these columns continue to grow and for the same reason they are destined to disappear when the stone that covers them falls. When dry, this moraine clay is as hard as stone; dampened it forms a porridge-like substance which begins to slip and flow downhill. In this way, over a period of time, the saturated earth slides down into the stream below and is washed away. This constant and continuous slippage is temporarily halted only when this erosion encounters a highly dry underlying ground being hard as rock which hinders further rapid slippage. In that way those steep faces develop up to 10 to 15 metres in height leading to the formation of the earth pyramids.

Wherever the moraine contains larger stones which keep the earth underneath dry and hard, earth pyramids are formed by literally being "washed" or eroded out of these cliffs. The higher the cliff and the higher up a suitable stone is found, the taller and mightier the resulting pyramid becomes. It is difficult to predict how long it takes until an earth pyramid has emerged because many constituents come together. Nor can you tell how old a pyramid actually is or will become. But you can tell for sure that once the top stone falls from the head of the pyramid, it is doomed and will soon face its corrosion since the unprotected material is then exposed to rain. As a consequence the column is getting smaller and smaller every time it is exposed to rain. While one earth pyramid slowly vanishes, further up the hill already a new one develops.