Gaisberg

Gravel from the Danube is found not only along the river but also on the hills above. In this case it is prehistoric Danube gravel originating from past glaciation. The higher the altitude, the older the gravel. The gravel still found on the Gaisberg hill was deposited during a very early ice age that began in the transition from the Pliocene to the Pleistocene age around 2.6 million years ago. This quartz gravel is embedded in a red loamy matrix that due to ages of weathering is rich in iron oxide. Deep and composed of material able to store large amounts of water, the soil is meagre yet well suited for a vineyard. The humus horizon is thick, ensuring an adequate supply of nutrients as well as better absorption and storage of water. This feature is particularly important in dry years.

The Danube gravel deposited during past glaciation can vary somewhat between vineyards. The lower third of this profile, taken from Gaisberg, is composed of sandy sediment. The gravel has a reddish colouring more similar to the red soils of the Mediterranean terra rossa variety than the brown soils of central Europe. This suggests that, as the iron oxides giving the soil its colour were forming, the climate was significantly warmer than during the period since the last ice age. While the terra rossa soils get their red colour mostly from the iron oxide hematite, the agent responsible in the case of brown soils is goethite, named after Johann Wolfgang von Goethe.