Northern Guam geospatial information server
The Mariana Limestone is an emerged reef. It forms 75% of the exposed limestone of Guam and dominates the surface of northern Guam and eastern flank of southern Guam. The ariana Limestone was mapped in the field as five facies (Tracey et al., 1964). The most prominent are the reef facies (a coral-algal incrustate limestone), detrital facies and molluskan facies (packestones and wackestones of lagoonal origin), and argillaceous facies (clay-rich rocks adjacent to volcanic terrain).