Fossil Leaf From The Ione Formation

Western Foothills Of The Sierra Nevada, California

Middle Eocene, 45 Million Years Old

This is an undescribed fossil leaf from the Eocene Ione Formation. Note the excellent preservation of the midrib (primary vein), secondary veins and the leaf margin; also present is a portion of the petiole (stem). Venation is pinnate, the margin entire---that is, the edge of the leaf is smooth and non-serrated. Reddish-brown coloration of specimen preserved on a feldspar-rich shale is due to the mineral iron oxide precipitated under very humid weathering conditions during Eocene times. Paleobotanists should be able to identify this specimen, eventually. An interesting feature of this particular fossil is the manner in which a portion of the leaf margin, along the left side, has been curled , suggesting deposition by rather turbulant waters during a period of flooding along the ancient floodplain. The roughly 45 million-year-old specimen came from an extraordinarily rich locality on private property in Amador County--a specific site currently under formal paleobotanical study by Dr. Jack A. Wolfe (retired member of the United States Geological Survey) and Howard E. Schorn (retired Collections Manager of Fossil Plants at the University California Museum of Paleontology in Berkeley), among others, who hope to use the fossils to help approximate the paleoelevation of the ancestral Sierra Nevada region during the geologic past.

Please note: All fossil localities in the Ione Formation of Amador County, California, presently occur on private property; explicit permission from the land owners must be secured before collecting fossils there.

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