In this study, nine florules from the Chloropagus Formation near Fernley, Nevada, are dated at 14.7-13.4 million years. The author finds that dominant mixed conifer forest and sclerophyll woodland species of the Sierra Nevada-Klamath region replaced exotic deciduous hardwoods in the two lowest sites. He concludes that this change reflects the loss of adequate summer rain as upwelling from a colder ocean resulted from spreading East Antarctic ice.

This volume presents a suite of detailed stratigraphic and sedimentologic investigations of the Eocene Green River Formation of Wyoming, Colorado and Utah, one of the world’s foremost terrestrial archives of lacustrine and alluvial deposition during the warmest portion of the early Cenozoic. Its twelve chapters encompass the rich and varied record of lacustrine stratigraphy, sedimentology, geochronology, geochemistry and paleontology. Chapters 2-9 provide detailed member-scale synthesis of Green River Formation strata within the Greater Green River, Fossil, Piceance Creek and Uinta Basins, while its final two chapters address its enigmatic evaporite deposits and ichnofossils at broad, interbasinal scale.

An Eocene (45 Ma) flora from Thunder Mountain caldera shows that montane conifer forest species from upper slopes descended to interfinger with mixed conifer-deciduous hardwood forest on the caldera floor then near 1700 m. Most species are allied to those in the western United States, but a few genera are in China. Precipitation was near 100 cm yearly, with most in summer.

The climate of the Earth has undergone many changes and for those times when geologic data are widespread and abundant the Mesozoic appears to have been one of the warmest intervals. This was a time during which the single continent Pangea disintegrated into continental units similar to those of today, a time when there were no significant polar ice caps and sea level was generally much higher than at the present time, and a time when dinosaurs apparently dominated terrestrial faunas and the flowering plants evolved. Understanding this alien world, ancestral to ours, is intrinsically interesting, intellectually challenging, and offers opportunities for more effective targeting of sites where commercially important geological resources may be found. It also provides critical insights into the operation of coupled Earth systems (biospheric, atmospheric, hydrospheric and geospheric) under extreme 'greenhouse' conditions, and therefore may have relevance to possible future global change. Our intention in organizing this Discussion Meeting was to bring together those who gather and interpret geologic data with those who model global climates from first principles. The community of workers who study the Quaternary have made significant advances by integrating and comparing palaeodata and climate model experiments. Although we have focused not on the Quaternary 'icehouse' but on the Mesozoic 'hothouse' climate we are well aware that approaches used in the study of the Quaternary may have relevance to earlier times.