c_sandstone = ndef->getId("mapgen_sandstone");
c_water_source = ndef->getId("mapgen_water_source");
c_river_water_source = ndef->getId("mapgen_river_water_source");
+ c_lava_source = ndef->getId("mapgen_lava_source");
// Fall back to more basic content if not defined
// river_water_source cannot fallback to water_source because river water