Northern Guam geospatial information server
About this map:
This map shows the elevation contours of the contact surface between the basement volcanic units and the overlying limestone units of the northern Guam plateau. The basement topography is highly significant because it guides the movement of groundwater and separates the NGLA into subsurface drainage basins. The source of the geospatial information is the 2013 volcanic basement map, an update of the original 1982 map produced by the Northern Guam Lens Study (CDM, 1982). The work on updating the map utilized geophysical and drilling data to correct and refine the understanding of basement topography and improve the map; see WERI Technical Report #141 (Bendixson, 2013). Details on the methodology used, content, and applications of the map can be found in WERI Technical Report #142 (Vann et al., 2013).