Petrified Forest National Monument, Arizona

A descriptive and illustrated account explains a vast deposit of fossilized conifer logs in Arizona: they were transported as driftwood into an ancient inland sea, sank in eddies, were buried in silt and later permineralized when silica and minerals replaced wood cells under great pressure. Subsequent uplift and erosion exposed brilliantly colored agate, jasper, and other gemlike cross sections, producing notable features such as a long natural bridge. The text also answers common visitor questions about why no standing trees remain, how the logs arrived and were dated, the kinds and sizes of trees, polishing and weight, and legal protections against removing specimens.