LATE QUATERNARY GLACIATIONS OF ECUADOR, PERU AND BOLIVIA

A review of late-Pleistocene glaciation in Ecuador, Peru and Bolivia is presented to accompany an ArcGIS digital map of glacial limits. Seven principal sites provide the basis of the current understanding of glacial chronology and this mapping compilation: (1) the Potrerillos plateau, Ecuador; (2) the Cordillera Vilcanota-Quelccaya Ice Cap, Peru; (3) the Junin Plain, Peru; (4) the Cordillera Blanca, Peru; (5) the Cordillera Oriental, Peru; (6) the Cordilleras Apolobamba and Real, Peru-Bolivia; and (7) the Altiplano, Bolivia. Minimum radiocarbon dates, the superposition of moraines, and relative dating methods provide evidence that the most extensive glacial advances pre-date the Marine Isotope Stage 2 (MIS 2). Ample series of well-defined, nested moraines indicate multiple episodes of glacial activity in the last glacial cycle, with a few minimum-limiting radiocarbon dates suggesting the local last glacial maximum (LLGM) occurred early in the last glacial cycle. There is also evidence of a late-glacial advance around 16,000 years BP, after the Northern Hemisphere MIS 2 maximum of ~21,000 years BP. Deglaciation from LLGM positions appears to have occurred rapidly. Evidence exists for a late-glacial readvance that may have pre-dated the Younger Dryas of Northern Europe. This work contributes to the INQUA Commission on Glaciation, Working Group on Extent and Chronology.