Top and bottom--Views of an abandoned hydraulic gold mine in the vicinity of La Porte, Sierra Nevada, California. The leaf-bearing upper Eocene La Porte Tuff (dated through sophisticated radiometric methods at 34.2 million years old) is the pale greenish layer at the rim; it yields some 43 species of of plants, most of whose closest modern-day counterparts live in southern Mexico, Central America, parts of South America, southeastern China, and the Philippines. Image at bottom clearly shows the stratigraphic relationship between the leaf-bearing, pale greenish late Eocene La Porte Tuff at the rim and the disconformably underlying plant-yielding middle Eocene brownish shales below. Photographs courtesy Larry Garside. I edited and processed them through photoshop.
Note--Always check with the US Forest Service to determine if unauthorized fossil collecting is allowed at the La Porte locality.