The Eocene Thunder Mountain Flora of Central Idaho (UC Publications in Geological Sciences)

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.