The sedimentary soil of the Langa originates from the Ligurian-Piedmontese Tertiary Basin.
The sediment that can nowadays be found in alternating layers developed on the seabed between 12 and 5 million years ago, during the Miocene.
The geological timescales range from Langhian (15,9-13,8 MA) to Serravallian (13,8-11,6 MA) to Tortonian (11,6-7,2 MA) and finally Messinian (7,2-5,3 MA). Over this time, the sea and the basin conditions changed dramatically and these changes are visible in the rock layers and in the various geological formations found in the Langhe:
- Murazzano Formation (Langhian-Serravallian): consisting of limestone and sand marls, we can find this formation in the highest zone of the towns South of Clavesana and Belvedere Langhe.
- The Lequio Formation (Serravallian): alternates sand and marls, resulting in soils rich in silt, clay and limestone. These can be found in the area of Barolo (centre-South of Serralunga and East of Monforte) and in the production area of Barbaresco (San Rocco Seno d’Elvio and Treiso). We also find the Lequio formation in Dogliani, Farigliano and Clavesana.
- Diano Sandstones (Tortonian): sandy strata originated from marine landslides. The soils are rich in sand with less clay and limestone and can be found in the area around Monforte, Castiglione Falletto, Barolo, Diano d’Alba.
- Sant’Agata Fossili Marls (Tortonian-Messinian): the most common formation in the Langhe of Barolo and Barbaresco. The soils present a consistent amount of clay and silt. They can be further divided into:
- Typicals: common in Grinzane Cavour, Verduno, Santa Maria di La Morra, the lowest part of Castiglione Falletto and Serralunga d’Alba, Barbaresco and part of Neive.
- Sandy: can be found in Dogliani, Clavesana, Dogliani, Monchiero; in Monforte, Castiglione Falletto and Annunziata di La Morra; in the highest part of Barbaresco, Neive, Albaand lowest area of Treiso.
- Laminate: found in Novello, La Morra and Verduno.
- La Morra Conglomerates (Messinian): found in La Morra only, they generate soils rich in gravel.
- Vena del Gesso Formation (Messinian): alternation of marls and chalk crystals. The soils are similar to the Sant’Agata Marls’ ones but enriched with chalk. Found on the western hills of La Morra e Verduno.
- Cassano Spinola Formation (Messinian): two different areas in La Morra and Verduno. The first has more sand, the latter is more similar to the Sant’Agata Marls Laminate.
- Pliocene Marls: found in a tiny area of the commune of Cherasco and characterized by a balanced presence of sand, silt, clay and less limestone.