The Pyrenees have experienced a very long geological evolution with multiple orogenies. Neoproterozoic crustal remains (Canigou, Agly) hint at possible Cadomian domains. Indications for Caledonian movements are somewhat clearer (conglomerates and volcanic rocks in the Ordovician). During the Variscan orogeny in the Pennsylvanian, the Axial Zone and the South Pyrenean Zone became an integral part of what was to become the microcontinent Iberia. The Sierras Marginales were part of the Ebro Block, a northeastern section of Iberia. The appartenance of the North Pyrenean Zone is still uncertain, but the Subpyrenean Zone certainly formed part of the microcontinent Aquitania. Iberia and Aquitania were on the south side of the South Variscan Thrust and therefore constituted the foreland of the Variscan orogen. Both microcontinents had originated from Gondwana's northern margin.