Abstract
In the Oligocene to earliest Miocene the entire southern Pyrenean foreland fold and thrust belt was backfilled and buried in up to 3 km of syntectonic continental conglomerates from the range's own erosional debris. Then, starting in the mid to late Miocene, the Pyrenees were exhumed by erosional excavation to their present relief. A model is proposed for this unusual development whereby late Eocene–Oligocene tectonic uplift of the margins of the Ebro basin raised local base level and blocked normal dispersal of erosional debris to adjacent oceans, thus causing the basin to fill then backfill northwards across the entire southern flank of the Pyrenees. Subsequent Miocene rifting of the Catalan Mediterranean margin, and the Messinian salinity crisis, lowered base level allowing the Ebro River to cut headward, capture the Ebro basin, and re-excavate the Pyrenees.
