A cold-based, debris-covered alpine glacier in Mullins Valley, a tributary to upper Beacon Valley, contains ancient glacier ice. Four independent dating techniques confirm that the glacier age ranges from ~10 ka near the valley head, to >8 Ma at its diffuse terminus in central Beacon Valley (where it abuts opposing buried ice that originated from Taylor Glacier; e.g., Sugden et al., 1995).  The dating methods include 1) cosmogenic-nuclide analyses of boulders from a sublimation till that caps the ice; 2) numerical ice-flow modeling of the glacier system; 3) 40Ar/39Ar analyses of in-situ ash fall from relict polygon troughs at the till surface; and, 4) modern horizontal ice-flow velocities as determined from synthetic aperture radar interferometry (InSar, from Rignot et al., 2002).  Multi-channel seismic surveys demonstrate that the ancient ice is ~45 to ~100 m thick in Mullins Valley and  ~150 m thick in upper Beacon Valley.