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 frost origin as the northern South Mowich Glacier, the Puyallup Glacier begins as a tributary to an ice stream that exits the Sunset Amphitheater. From this split point around , the glacier expands into a broad sheet of ice with elevations ranging from  to .