Clay
A fine-grained mineral soil with high cohesion and strong water-holding capacity. Its cool temperatures and abundant moisture slow ripening and favour high-acidity, late-maturing varieties such as Merlot.
Silt
a medium-grained mineral soil with moderate water retention and fertility. Its tendency to encourage vigorous growth can soften wine structure unless managed closely. (Loess is a wind-deposited fine silt)
Loam
a balanced mixture of sand, silt, and clay with naturally high fertility. Its vigour-promoting nature demands careful canopy and yield management to avoid dilute wines.
Sand
a loose, coarse-grained soil composed of weathered mineral particles. Its warmth, extreme drainage, and low fertility produce light-bodied, aromatic wines and often allow vines to survive phylloxera ungrafted.
Sandstone
a sedimentary rock formed from compressed sand grains, often silica-based. Its warm, free-draining, nutrient-poor nature limits vigour and yields small berries, producing concentrated, structured wines.
Gravel
a coarse, stony alluvial soil composed of large mineral fragments. Its warmth, rapid drainage, and low nutrients help late-ripening varieties achieve full maturity, producing structured, age-worthy wines. (Galet Roulé in Châteauneuf-du-pape, Gimblett Gravel in Hawks Bay)
What impact does limestone-based soils (Chalk, Limestone, Marl) have?
They provide good drainage and moderate fertility, helping to control vine vigour. High PH also limits potassium uptake and helps toretain acidity in grapes and promote balanced ripening. As a result, wines from limestone soils are often fresh, structured and elegant, with good ageing potential. (Terra Rossa in Coonawarra, Tuffeau in Vovray and Saumur, Alberese in Tuscany)
Marl
a mixture of limestone and clay, typically containing roughly equal proportions of each. Its cool, moisture-retentive, alkaline nature slows ripening and supports high acidity, structure, and age-worthy wines. (Kimmeridgian Marl in Chablis).
Alluvial
are river-deposited mixtures of gravel, sand, silt, and clay. Their generally good drainage and heat reflection enhance ripe, fruit-driven styles across many climates.
Basalt
is a lave-derived mineral-rich igneous rock that weathers into iron- and magnesium-rich soils. Its mix of good water retention and drainage supports high-acid, pure, mineral wines.
Tuff
is an ash-derived porous, consolidated volcanic ash with moderate fertility and high aeration. Its easy root penetration and moisture balance favour high-quality aromatic whites. (Tokaj)
Slate (Schiefer)
is a fine-grained metamorphic rock that splits easily and absorbs heat efficiently. Its warmth, poor fertility, and fast drainage encourage slow, even ripening and produce high-acid, intensely aromatic wines such as Mosel Riesling. (Llicorella in Priorat).
Granite
a coarse-grained igneous rock composed of quartz, feldspar, and mica that weathers into acidic, nutrient-poor, free-draining soils. Its warmth, low fertility, and rapid drainage reduce vigour and enhance aromatic purity, producing fresh, high-acid, perfumed wines such as Beaujolais Crus, Albariño from Galicia, and certain South African Chenin Blancs.
Schist
a layered metamorphic rock that fractures into plates, allowing deep rooting. Its warm, free-draining, low-nutrient profile produces powerful, mineral, textured wines with concentration. (Xisto in Douro Valley, Galestro in Chianti Classico)
