[1] The Tagnone rises in the commune of Vezzani to the northeast of the 1,532 metres (5,026 ft) Punta Paglia.

To the south it is separated from the Fium'Orbu valley by a line of heights that are above 1,000 metres (3,300 ft) high until the edge of the coastal plain.

[3] The villages of Vezzani and Pietroso cling to the slopes in the upper part of the narrow valley.

[4] The environment on the north-facing slopes favors forestry, and laricio pines of the Rospa-Sorba national forest grow on the foothills of Punta Paglia above the villages.

The valley floor is not wide and flat enough for agriculture, which is confined to terraces around Vezzani, Pietroso and a few hamlets.