Caballo Island Caballo Island Caballo Island (which means "Horse Island" in Spanish) is a bluff, rocky island located at the entrance to Manila Bay in the Philippines. It is about long with the highest elevation at 381 feet high. Caballo, along with the larger Corregidor (2 km to the north), divides the entrance to the bay into two broad and deep channels, known as the North and South Channel. The whole island was formerly occupied by Fort Hughes, a U.S. defense fortification before World War II. It was heavily bombed during the war. Caballo and Corregidor Islands are believed to be the
Caballo Mountains 34.9 Ma. What is now the San Mateo Mountains (Socorro County) contained at least two cauldrons, the Nogal Canyon cauldron (28.6 Ma) and the Mount Withington cauldron (27.4 Ma). Local subsiding appears to have begun around 34.9 Ma. The Caballo Mountains began to rise in the late Oligocene, and throughout the Miocene. Approximately 9.6 Ma, the eruption of basalts near Fort Selden signaled the renewal of crustal extension and volcanism in the southern part of the rift. Activity along both older and new faults increased the number, but decreased the width of basins along this portion of the rift. The