Figure 5: Harker diagrams showing the variation of major elements in ECS, SMR, and BT. The El Cajete series (ECS) has SiO₂ < 75 wt%, and shows a general increasing trend for SiO₂ from early eruption ECP, to BAT, to later BB. Al₂O₃, FeO, CaO show negative trends while MgO, Na₂O and K₂O show positive trends with increasing SiO₂ for ECS. SMR forms trends distinct from those of the ECS. With increasing SiO₂, Al₂O₃, FeO show negative trends and K₂O shows a positive trend with different slopes for SMR samples compared to ECS; MgO, CaO, and Na₂O for SMR show reverse trends compared to ECS. The trends of the Bandelier Tuff are similar to those of the SMR. (BB = Banco Bonito Lava Flow, BAT = Battleship Rock Tuff, ECP = El Cajete Pumice Fall, SMR = South Mountain Rhyolite, and BT = Bandelier Tuff).