Fossil Plants From La Porte Hydraulic Gold Mine

Sierra Nevada, California

Top to bottom--Plant fossils from an abandoned hydraulic gold mine in the neighborhood of La Porte, Sierra Nevada, California. Top--A leaf fossil from the upper Eocene La Porte Tuff. Seems to most closely resemble what Susan S. Potbury called Cornus kelloggi, a presumably extinct species that has no known exact living counterpart. A dogwood, possibly akin to an extant species in southeast Asia. Early paleobotanists thought it resembled the living Pacific Dogwood Cornus nuttalli. Middle--Two fossil leaves exposed by natural erosion on the surface of a block of upper Eocene La Porte Tuff. Specimen at left is most similar to what paleobotanist Susan S. Potbury called Hyperbaena diforma, the Eocene analog of the living Hyperbaena smilacina, a member of the Moonseed family, several members of which contain the toxic alkaloid Tubacvurarine, used to prepare various forms of curara. Usually a twining woody vine, more rarely an upright shrub. Now native to Colombia, Costa Rica, and Nicaragua. Leaf at right looks a lot like what Susan S. Potbury described as Styrax curatus, the Eocene variety of today's Styrax arengteus, sometimnes called Snowball. It's an evergreen tree usually topping out at around 65 feet, with occasional specimens to 98 feet. Harvested in the wild for an aromatic resin that is used locally. Ranges today from Panama to Mexico at elevations from roughly 300 to 5,577 feet. Bottom--A chunk of carbonized wood (not petrified, or permineralized) from the middle Eocene shales that disconformably underlie the upper Eocene La Porte Tuff. Genus-species indeterminate. Note US nickel for scale (0.835 inch, 21.21 mm in diameter). Photographs originally taken with a Minolta 35mm camera.

Note--Always check with the US Forest Service to determine if unauthorized fossil collecting is allowed at the La Porte locality.

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