Geological Formation of the Langhe
The Langhe and Monferrato formations are traced to marine sediments deposited when the area formed part of the Gulf of the Po Valley approximately 8–10 million years ago. The resulting marl and sandstone formations are rich in calcium carbonate.
Four groups are distinguished: the ancient Lequio Formation of grey marl and siliceous sandstone; carbonate-cemented Diano sandstone; Tortonian Sant’Agata marl rich in magnesium and manganese carbonate; and less vine-favourable gypsum- and sulphur-bearing areas. Lequio is associated with structure, tannin and longevity; Sant’Agata with delicacy, fruit and restrained tannin; and Diano with an intermediate balance of finesse, structure, complexity and ageing capacity.
Most Giribaldi vineyards lie on Diano sandstone and carry Dolcetto, Arneis, Favorita, Barbera and Nebbiolo. A smaller share occupies Sant’Agata marl, while a limited Langhe Nebbiolo component lies on Lequio formations.