Complex sentence: Geologically it is an eastern prolongation of the Galician Massif with Paleozoic folds and cut by dee east-west oriented canyons such as the Cares River valley.
Split into simpler sentences: Geologically it is an eastern prolongation of the Galician Massif with Paleozoic folds. It is cut by deep east-west oriented canyons such as the Cares River valley.