Sharing the same source of ice as the northern South Mowich Glacier, the Puyallup Glacier begins as a branch off the ice stream that flow out of the Sunset Amphitheater. From the split at around , the glacier expands into a broad sheet of ice ranging from  to  in elevation.
Sharing the same source of frost as the northern South Mowich Glacier, the Puyallup Glacier originates as a tributary off the ice stream that emerges from the Sunset Amphitheater. From the divergence around , the glacier expands into a broad sheet of ice spanning from  to  in elevation.