Cagayan Valley

Region II


Cagayan Valley is located in the northeastern section of Luzon. Most of it lies in the Cagayan River Valley between the Cordilleras and the Sierra Madre mountain ranges. The bedrock is Miocene to Pliocene sedimentary rock including shale, sandstone, siltstone and limestone. The marine sediments contain fossils of coral and other marine organisms. The Sierra Madre and the foothills of the Cordilleras have Cretaceous coarse-grained igneous rock. The main karstified areas are in the Callao Limestone at the east margin of the Cagayan valley, and the Sicalao Limestone at the western and southern-southeastern margin of Cagayan valley.