The major types of sedimentary soil in California’s wine country include calcareous soil, chalk, limestone, alluvial soil, benchland soil, slate, and tufa.
Calcareous soil is made of sediments with a significant amount of calcium carbonate. It has a fairly high pH and is alkaline, thus imparting acidity into grapes. Fossilized shells of sea life are weathered over time and break down to for calcareous soils.
Chalk is a white sedimentary soil that drains well and is not very heat retentive. It has a high pH level and encourages acidity to develop in grapes. Burgundy is famous for its chalk and limestone soils.
Limestone is made mainly of calcite and silica as well as some amount of sand, silt and clay. Decomposed ocean life creates calcite over millions of years. Limestone without a lot of other materials mixed in is white.
Alluvial Soil is formed over many years by the movement of water. Running water washes gravel, sand, silt and clay down its path. Alluvium washed down from the watersheds of adjacent hills will form an alluvial fan.
Benchland soil forms from alluvial deposits at the base of hills. Benchlands are often raised above the valley floor and contain much older alluvium. They are often leeched of nutrients and are porous from water percolation over the years.
Tufa forms when calcium rich bodies of water dissolve very slowly. When this occurs, calcium carbonates solidify in coarse formations. Tufa is useful as a construction material.