Geologie Information

The granite-like quartz-porphyry plateau of the Ritten, with its various but predominantly purplish colours, is part of the largest exposed area of volcanic rock in the Alps, in striking contrast to the limestone of the Dolomites. Because of the way the porphyry is fractured, it does not hold groundwater, and as a result much of the Ritten, although well supplied with good soft drinking water, suffers shortages for agricultural purposes in dry years. The chief sources of agricultural land on the plateau, therefore, are moraine soils deposited from the late ice age glaciers of the Eisack and neighbouring valleys, which also deposited the small amounts of lime found on the Ritten (one of the reasons why older buildings were almost entirely of wood - there were no raw materials for mortar).

Moraine clay and boulders embedded in it are also the source of the Ritten's famous "earth pyramids". These curious boulder-topped spikes are formed when water erosion of a steep moraine cliff exposes hard igneous rocks, which then become protective caps that keep the clay immediately underneath dry, hard, and thus immune to further erosion until the stone cap eventually falls off. The process is continuous, with new pyramids forming as old ones disappear.

Where larger portions of the clay remain, on top of the harder porphyry, groundwater is held and provides better agricultural land, but may also create the moors, locally called Moos, that are another common feature of the Ritten landscape.