Explanation geological map of the Paleozoic of the southern Cantabrian Mountains 1 : 50.000 Sheet 1 Pisuerga

The Carboniferous Pisuerga basin developed north of the León line and as such is the most eastern one of the Asturide basins. The Carboniferous sequence is subdivided into Ruesga Group (roughly Lower Carboniferous + Namurian), Yuso Group (roughly Westphalian) and Cea Group (roughly Stephanian). Since the beginning of the Yuso Group the Pisuerga basin became subdivided into a western and eastern basin and since the beginning of the Cea Group the western basin became subdivided into two separate basins. The main folding started during the Stephanian. A remarkable interaction of epeirogenic and orogenic movements leads to the analysis of a close relation between sedimentological and structural features. Several pronounced structural lineaments can be traced to have been active since the Middle Devonian into the Tertiary.