Definition - What does Siliceous Soil mean?
The siliceous soil is a composite of soil with acid rocks which appear to be crystal-like. This type of soil is found in over half of the Bordeaux wine regions. It is also found in the wine region of Salta, Argentina. Siliceous soil has the ability to retain heat, however, it does best when combined with clay and/or silt as these elements help retain water and aids in helping the vines survive during dry periods.
WineFrog explains Siliceous Soil
Siliceous soils for the cultivation of vineyards is advantageous, especially in regions where cooler evening temperatures are common. As the soil retains the heat it stores from the day, it can aid in the plants' photosynthesis process and for consuming food it produces during the day. Siliceous soils, consisting of silica have also proven to aid in the grapevine's resistance to fungus. In a region such as Bordeaux, a region whose 50% of soils consist of silica and where weather and precipitation may come at less-than-desirable times, this is advantageous.