Roero is an area that lies to the north of Alba (Piedmont), on the left bank of the River Tanaro, between the plain of Carmagnola and the low hills of Astigiano.
From a geological point of view it is quite a young land, despite resting on a very ancient crystalline base. Up until 130 million years ago it was part of the bottom of an inland sea, called the Golfo Padano. Its terrain was formed by the sedimentation of debris of various lithological origins transported by marine currents that eroded the surrounding mountains, layering them through various stages of drying up and immersion.
Roero remained a shallow gulf until the Pliocene, as shown by the sandy sediments and marine clays. The emergence and formation of the Roero hills took place 2-3 million years ago. This drift also brought various types of soil to the surface: the deeper layers shifted uphill, whereas those more recent remained at the bottom of the valley.
After the final surfacing the soil was covered once again by sediments of alluvial and wind origin. In that period Langhe and Roero formed a single plateau with the Tanaro and the Stura in the direction Bra – Carmagnola. The great friability of this marine-origin soil led to a progressive erosion. This shift occured between 220.000 and 150.000 years ago along the path of the Tanaro in the direction Alba – Asti, separating Langhe and Roero.
The erosion of the river had a significant effect on the sandy soil of Roero, creating the Rocche, craggy mountain peaks that mark the watershed between the old and new Tanaro valley. They cut the territory from south-west to north-east, from Pocapaglia to Montà, dividing the continental gravel and fluvial clay soils from those of marine origin, providing ideal vine-growing conditions.
This is how the Roero territory was formed on the left bank of the river Tanaro.