Definition - What does Loess mean?
Loess is a type of soil that has been formed by continuous deposits of clay and sand which are held together with limestone. Other components of this soil type include feldspar, mica and up to 80% of quartz along with other minerals.
The word loess is German for "loose," which is the nature of this soil.
WineFrog explains Loess
Loess is a soil type ideal for growing wine grapes, as it is porous and well-draining. The composition of the soil is also a good source of minerals that grape vines need to thrive.
Loess soils cover about 10% of the earth's crust and can form deposits up to a few meters thick. It is marked by a brown-yellow color and is a product of past glacial activity.
This type of soil can impart mineral characteristics to wine, especially white wines. This terroir can be found in Germany and Lower Austria where many white wines made from Riesling and Grüner Veltliner are prized for their minerality.
The AVA Walla Walla Valley in Washington state is also known for its loess soils.