Design Ideas

Tonto Natural Bridge: The largest travertine arch in the world

When you think of travertine, tiles and pavers might be the first things that come to mind, but there are other items that can be made out of travertine, too – like bridges. As travertine is a naturally formed stone, it makes sense that some of the world's most beautiful geological formations are made from this material. One of the most impressive, the largest travertine arch in the world, happens to reside in Payson, Ariz. Known as Tonto Natural Bridge, this gorgeous travertine bridge is at the center of a state park. Here's a breakdown of how it was made, its history and why it's worth a visit.

How travertine forms
Travertine is a crystallized form of dissolved limestone that results from the deposition of calcium carbonate in fresh water. Essentially, it's a type of sedimentary rock that develops when calcium-carbonate rich spring water evaporates through stone. When travertine is freshly made, it's usually white, but then turns grayer with age. However, it can also come in shades of red, brown or yellow depending on whether other minerals were present, like iron. Many travertine formations are made near geysers or hot springs, and even stalagmites and stalactites in caves are sometimes made from travertine.

In the case of Tonto Natural Bridge, millions of years ago, the west side of Pine Creek was formed by a flow of lava, which then eroded and left behind purple quartz sandstone. These layers of rock were then lithified, tilted and faulted over the years. Sea water then covered the area (yes, in Arizona!), depositing sand and mud over the rock. More volcanic eruptions then covered the rock, forming a basalt cap. This cap broke down and was moved by faults, eventually creating Pine Creek Canyon. After that, rain soaked deep underground through the rock, which formed limestone aquifers. Springs were made as a result, and they carried the dissolved limestone and calcium carbonate to form the travertine dam. Finally, the waters of Pine Creek eroded through the travertine to form the natural bridge.

Tonto Natural Bridge history
We know how it was made, but the bridge wasn't officially discovered until 1877, when a prospector named David Gowan came across the formation as he was being chased by Apaches. He spent two nights and three days in one of the caves on the inside of the bridge to escape discovery, then finally left his shelter to explore and claimed squatter's rights on the land. In 1898 he convinced his nephew, David Gowan Goodfellow, to emigrate from Scotland and settle the area. Tonto Natural Bridge State Park was officially opened and dedicated June 29, 1991, after years of legal efforts.

Amenities for visitors
If you want to get an up-close look at this travertine marvel, which stands 183 feet high over a 400-foot long tunnel that's 150 feet at its widest point, there's plenty to do in the park. Visitors can stand on top of the bridge or hike down to explore the surrounding area on one of three trails: Pine Creek Trail, Waterfall Trail and Gowan Trail. There are also several facilities for group gatherings, grass areas, a ramada with picnic tables, a barbecue and electricity for convenience. Open seven days a week from 9 a.m. to 5 p.m., visitors can spend all day surveying the beauty of the travertine and the wildlife and vegetation that surrounds it. The park has won three Best of Rim Country awards cementing its reputation as a must-see site in Arizona, including Best Historic Site, Best Place to Hike and Best Day Trip.

# # # # # #