the Miocene Tagpochau rocks with an angular unconformity. Talus, marsh sediments and limestones such as the Mariana Limestone are common across the surface, resulting from deposition and mass-wasting during the Pleistocene and Holocene. Structural geology Normal faults are common on the island, particularly the Angingan fault which places Fina-sisu Formation volcanic rocks against younger limestones. Geologists have identified breccia near Mount Tapkpochao as the trace of a normal fault. The Angingan, Obyan and Dago faults may be part of a larger, anastomosing fault system, running on both sides of the central highlands and connecting with faults in the area of Suicide Cliffs and Fanonchuluyan Bay. Most faults trend north-south and even young rocks from the Holocene show signs of offset. References +Northern Mariana Islands Geography of the Northern Mariana Islands