National Geographic : 1956 Mar
© National Geographic Society 4 Forty-niners Passed This Treasure By in Their Avid Search for Gold Miners who washed the stream gravels at You Bet, California, for flecks of yellow metal ignored "worth less" hillocks of clay. But in them paleontologists found the imprint of a sycamore leaf. Its color devel oped in clay some 45 million years ago. Staff Photographer B. Anthony Stewart +4 Fossil Coral Presents Two Faces: a Mirror Study in Contrasts This reef-building animal colony lived in warm Flor ida waters in early Miocene times. Reflected view shows the outer form preserved with silica that replaced the coral skeleton. Pencil points to structureless chal cedony that lines the interior.