Radiocarbon-dated sediment cores collected from lakes in the Temple Lake valley suggest that valley-wall rock glaciers adjacent to these lakes were not active during the Holocene, but are late Pleistocene in age. The absence of well-graded coarse clastic material in the cores and the general consistency of sediment characteristics through the Holocene suggest that slumping and turbidity flows did not contribute significantly to the lacustrine sediment record as would be expected had the rock glaciers advanced into these lakes. In addition, the advanced weathering of the rock glacier deposits can be used to support a late Pleistocene age. Such conclusions challenge the interpretation of the weathering characteristics of these deposits (i.e., relative age), and thus challenge the early Neoglacial age (3000 to 5000 BP) for these rock glaciers. Consequently, more reliable chronologies of high-alpine glacial and periglacial activity may be gleaned through the use of continuous records of lacustrine sedimentation from appropriately located lakes in conjunction with relative-age techniques.