The natural monument is centered on the mountain of salt mines ( ) in the barangay of the same name in Bambang municipality near the confluence of Magat River and Santa Cruz River in the Upper Magat River Basin . This once snow-white mountain of travertine situated on the southeastern slopes of the Cordillera Central contains the Salinas Salt Springs , a popular attraction in the province during the early days of Spanish and American colonial periods . The mountain of salt was formed through the continuous flow of a natural spring containing sulfate and carbonate salts over millions of years . When the 1990 Luzon earthquake hit the area , tectonic movements caused the underground water to be diverted leaving the whitish mounds dry and causing them to turn gray . At present , this mountain at Sitio Bansing once known for its salt industry is being utilized as fishponds arranged in terraces on the mountainside for freshwater fish such as '' tilapia '' and African sharptooth catfish , including the giant freshwater prawn
1990 Luzon earthquake
1990 Luzon earthquake
Salinas Natural Monument