THE NAME WINDBLOWN SAND REFERS TO THE MODE OF TRANSPORT. During the ice age, stormy winds winnowed sand from the gravel beds of the Rhein and Main rivers. The coarse and heavy sand grains could not be blown very far and accumulated as dunes on the plains of the Rhine valley. Since the wind speed decreased with height, the grain size of the sands decreases and the silt fraction increases with height. Windblown sand contains more than 75% sand. The sands of the Rhine are calcareous and those of the Main are decalcified.      Windblown sands cover about 10% of the wine region Hessische Bergstrasse. They are found on the level regions at the foot of the Bergstrasse. Soils formed on windblown sands are rare in the Rheingau. A small patch can be found near the Main at Hochheim. HEAT AND WATER The soil was formed on calcareous windblown sands from the Rhein. The dark colours of the soil are due to the humus content, which also improves the water capacity and nutrient content. Windblown sands with elevated fine sand contents are friable and easily penetrated by roots. The natural soil horizons have been lost to erosion or were incorporated into the soil profile by ploughing. The sand of the subsoil contains several thin layers of granodiorite rubble. The granodiorite comes from the upper parts of the slope. The rubble was mixed with the sand and loess sediments during the ice ages. Solifluction caused this mixture to move downhill.      Sandy soils are moderately fertile but also have special qualities. The pores between the coarse sand are too large to be able to store water. However, the water holding capacity is improved by the presence of loess. Surplus water percolates  rapidly  into  the

WINDBLOWN SAND Hortic anthrosol form- ed on windblown sands. This soil was formed on the calcareous wind- blown sands of the Rhine.

deeper soil horizons. The roots of the vines can easily penetrate deep into the friable soil to tap into the water stored below. The sand is well aerated, warms rapidly and therefore promotes early flowering and ripening. The calcareous windblown sand contains plenty of calcium which improves the nutrient potential.

SOIL PROPERTIES   medium soil water capacity   very good rootability   very good aeration   very good warming capacity   calcareous   moderate mineral nutrient potential