How did the collision of the Iberian and European tectonic plates build the Pyrenees?

The formation of the Pyrenees resulted from the convergence of the Iberian Peninsula and the European plate. Until approximately 90 to 100 million years ago, the Iberian Peninsula was positioned against the western margin of France.12

The process began when the peninsula started to rotate into its current position, a movement that opened the Bay of Biscay behind it. As the Iberian Peninsula moved toward southern France, the resulting collision generated a combination of crustal shortening and strike-slip deformation.12

While this tectonic activity began during the second half of the Cretaceous Period, the primary mountain-building phase occurred during the Eocene and Oligocene epochs. Under these intense folding forces, more plastic sedimentary layers folded without breaking, while the rigid granitic base fractured and became dislocated. This upheaval created the narrow, high-walled range that today serves as a boundary between France and Spain.314