Agate Bridge

Agate Bridge is a petrified log crossing a gully on Agate Mesa, a short roadside stop on the park road. It’s worth a brief look if you want to see how a fossilized tree can span a wash, but the large concrete support is part of the view and makes the bridge look less natural than its name suggests. Walk from the parking area to the viewing point; you can’t cross the log on foot.

The log spans about 40 feet across the chasm and sits 16 feet above the canyon floor. From the viewpoint, look at the trunk, the concrete beam beneath it and the brush-filled wash below. Keeping all three in one photo shows both the fossilized tree and the work that keeps it in place.

Agate Bridge was first called Natural Bridge, and visitors once posed on the log. Concern it might collapse led to masonry pillars in 1903, concrete support in 1911 and the concrete beam still visible today in 1917. The beam cost $1,700; the government paid for it and the railroad installed it. In the late 1800s, paleobotanist Lester Ward called it the world’s most noted single petrified log.

Agate Mesa is capped by the lower Rainbow Forest bed of the Sonsela Member, a sandstone and conglomerate layer that contains the Rainbow Forest logs. The Sonsela Member dates to about 216 million years ago; that’s the age of the rock layer, not a confirmed age for this individual log.

There’s parking and interpretive information at the stop. There’s no drinking water at stops along the park road; fill up at the Painted Desert Community Complex or behind Rainbow Forest Museum before continuing. A park entrance pass is required.