Appears in

Oxford Companion to Wine

Oxford Companion to Wine

By Jancis Robinson

Published 2006

  • About

geology is the scientific study of the solid Earth, although the term has also come to refer to the materials and processes involved with it. Vineyard geology, therefore, means the ground in which the vines are rooted. The loose earth on the surface is derived from bedrock and, if it can support plant life, is called soil. Because grapevines can thrive in strikingly stony soil and root into bedrock, the distinction in vineyards between rock and soil is unusually blurred.

Many of the world’s vineyards are located on sediment that is now distant from its source, while in others the soil is derived from the local bedrock, which may be visible as outcrops protruding through the loose material. All exposed bedrock is under constant chemical and physical attack (weathering), breaking it down into the smaller fragments generally called stones (see stones and rocks). Smoothed pieces a few centimetres or so across are referred to as pebbles, or cobbles if larger. As the material is further fragmented, into sand, silt, and clay, it becomes soil. Loose material on hillsides tends to slip down the slope due to gravity (see colluvium). The world’s largest vineyards are on flat plains, carved by rivers over millennia and now covered by alluvium. All these fragmented products and the bedrock itself are composed of minerals.