The first things you'll notice at Petrified Forest National Park are the dozens of logs lying atop hills as if on display, many of them pointing in the same direction. Closer up, you can see the colors in the wood -- reds, greens, yellows, blues, and purples, all of them rich and moist looking, like wet paint. The colors might tempt you to touch the wood, and if you do, you'll find that it isn't wood at all, but cold, hard stone.

More than 200 million years ago, these petrified trees were enormous conifers growing in a tropical forest. Floods swept them into large rivers, tearing off their branches in the process. Eventually, the trees bottomed out in the shallow waters of the flood plain, where silt, mud, and volcanic ash buried them. Because almost no oxygen could reach the entombed trunks, they were slow to decay. Silica from the ash permeated the trunks, replacing or filling the wood's cells before leaving quartz in its place. Minerals such as iron and manganese streaked the quartz with colors. The result: The wood became beautiful rock.

Recognizing the value of this rock, early settlers began shipping it out on East Coast-bound trains. When the residents of the Territory of Arizona realized that the "wood" might soon be gone, they petitioned Congress to protect the "forests." Using the Antiquities Act, President Theodore Roosevelt created Petrified Forest National Monument in 1906. Congress designated it a national park in 1962.

The same sediments that entombed the trees buried other plants and animals, preserving them as fossils as well. Erosion has exposed these clays and sandstones, collectively known as the Chinle Formation. With little or no vegetation to hold them in place, the sediments erode quickly and unevenly, forming mesas, buttes, and furrowed, conical badlands, unearthing thousands of fossils, including bones from some of the most remarkable creatures ever to inhabit the earth. In addition to the 200-million-year-old fossils, there is evidence that the ancestral Puebloans (also known as Anasazi), ancestors of the modern Pueblo people, once occupied this area. Evidence of other human occupation dates from 10,000 years ago.

Even without these wonders, it would be worth coming here to see the rich reds, grays, and maroons of the Painted Desert. Shaped like a tusk (with the wider end near Cameron, AZ), the desert spreads from near Holbrook in the south to the Hopi mesas in the northeast, to near the Grand Canyon in the west -- far beyond the boundaries of the park. Its seemingly barren landscape is home to a rich diversity of plant and animal life: desert grasses; wildflowers, including Indian paintbrush and globemallow; juniper and other trees; mammals, including pronghorns, cottontails, and porcupines; reptiles, including collared lizards and western rattlesnakes; and birds, the most prominent being the raven.