Thursday, November 7, 2013

Hike through petrified Triassic-era forest

Great Logs Trail, courtesy Petrified Forest NPS.
Topo map, Great Logs Trail.
Families can hike the remains of a woodlands dating from the dinosaurs’ earliest days on the Great Logs Trail in Petrified Forest National Park.

The fairly easy walk consists of two loops that combine for a 0.6-mile round trip. Because of the hot Arizona weather, spring and autumn mark the best time to hike the trail.

To reach the trail, from Interstate 40, take Exit 311. After passing the entrance station, drive the park road, which loops back under the freeway and heads to Petrified Forest’s southern section. After passing the Crystal Forest area, look for the Giant Logs and Rainbow Forest Museum turnoff on your right/west, about 26 miles from the entrance station. Park at the museum.

The trail begins at the museum’s back entrance, where interpretive brochures are available. If the museum is closed, simply walk to the building’s north side to pick up the pathway.

Along the trail’s inner and outer loops are 10 major sights. Without a doubt, the most impressive of them is Old Faithful, a fossilized tree stump whose base is nearly 10 feet across and would extend 35 feet high if standing upright.

Some 225 million years ago during the late Triassic, the petrified logs along the trail were part of a large forest that covered this part of the world. Nine different tree species – all of which are extinct – as well as ferns and more than 200 other plant species, were fossilized when floods washed them into riverways. Sediment and volcanic ash covered the fallen plants before they could decompose.

Water with dissolved minerals entered the plants’ cells, literally turning it to stone and preserving the tree’s exact shape. The different colors in the petrified wood come from the type of mineral entering the cell. Blue and purple indicate manganese; yellow, orange and red is iron; green is copper; black is carbon; and tan and gray suggest the water had very low mineral content.

A petrified fossil is extremely heavy and hard. It averages 150-180 pounds per cubic foot and can only be cut with a diamond-tipped saw.

The Rainbow Museum contains several exhibits about petrified wood and paleontology in the park.

Pets are allowed on the trail but must be leashed at all times. Though a paved trail, some sections would be difficult for a wheelchair to navigate; in addition, the trail sees an 82 feet change in elevation.

While the ground about the trail appears to be brimming with petrified wood fossils, removal of even the smallest chunk is illegal. To that end, park officials often search vehicles exiting the park for petrified wood. If you’d like a souvenir piece of petrified wood (and who wouldn’t?), you can purchase it legally from roadside stores outside the park. That petrified wood is collected on private land surrounding the national park.

Learn about other great America national park sights in my Best Sights to See at America’s National Park guidebook.