Above: Samples from Lugana and Valpolicella to the east give you an idea of how varied the composition of the soil is there.
Professor Attilio Scienza is widely regarded as Italy’s leading ampelography and researcher focused on the study of terroir. The following is culled from his study of the unique soil types found at Sansonina.
Lake Garda was formed by the retreat of a large glacier that covered the expansive valley here. Its retreat marked a long and intense period of glaciation.
The Würm was the fourth and last phase of the cooling of the earth. It was a classic example of the erosion and accumulation of detritus that the glaciers left behind as they retreated from the most barren areas of the Alps.
Roughly 20,000 years ago, climatic pulsations created the material that would ultimately become the morainic basin as we know it today. The basin created by the glacier would become the dam that prevented the melting ice and water to flow into the Po River Valley. That plain was submerged by the sea during the previous geological era, the Tertiary Period.
The soils found today at Cascina Sansonina were appeared roughly 5,000 years later. They were created by the bottom of a lake that had formed as the glacier retreated and the earlier morainic basin, known today as the Pozzolengo basin. The deposits left by the glacier are very distinctive and very different from morainic soils found in the basin. The former are made up of larger stones and coarse gravel. They are also different than the soils formed by the sides of the glacier’s ice tongue, the so-called Kame terraces. The latter are much more heterogeneous, formed by sandy material alternated by fine, compressed layers.
When the glacier finally melted, the glaciolacustrine silt was marked, in some places more deeply than other, by the lines of drainage that stretch from the morainic hills toward the lake. Along their banks, the lacustrine (lake) deposits and colluvial (sink-shaped) deposits are richer in gravel than the soils that the water passed over.