Late miocene vegetational and climatic variations inferred from a pollen record in northwest wyoming

A pollen stratigraphy from late Miocene lacustrine strata (Teewinot Formation) in Jackson Hole, Wyoming, permits analysis of vegetation and climate history over a time interval of less than 300,000 years with better temporal resolution of data than has been reported from terrestrial Tertiary deposits. The flora was essentially modern, and six successive pollen assemblages indicate alternating dry and wet conditions. The frequency of climatic change in this record is similar to that inferred from marine isotope records for both late Tertiary and Quaternary time.