 There were also a few rare shouldered adzes dated 2000 years BC, together with ‘Luzon Ridged Adze’ in the river valley of San Juan, the upper Novaliches and Marilao valleys.The concentration of artifacts discovered by Dr. Beyer might be an indication of habitation.In the present day San Francisco del Monte area, an extensive deposition of damaged polished adze were found with wornout flake tools mode of obsidian, or volcanic glass and tektites.