Are there "Living Glaciers" in the Sierra?

In addition to Muir's theory that Yosemite Valley was created by glacial carving he also believed that there were still "living glaciers" in the high Sierra. In his August-October 1872, Yosemite Creek, etc. journal, he notes that the stakes he placed in a straight line across the McClure Glacier on August 21 were now pushed down the mountain indicating a moving glacier and not simply a patch of snow.