Lithostratigrahic and mineralogic analyses of sediments from hypersaline Bainbridge Crater Lake, Galápagos Islands, provide evidence of past El Niño frequency and intensity. Laminated sediments indicate that at least 435 moderate to very strong El Niño events have occurred since 6100 14C yr BP (∼7130 cal yr BP), and that frequency and intensity of events increased at about 3000 14C yr BP (∼3100 cal yr BP). El Niño activity was present between 6100 and 4000 14C yr BP (∼4600 cal yr BP) but infrequent. The Bainbridge record indicates that there has been considerable millennial-scale variability in El Niño since the mid-Holocene
